Guide to PKU - Mead Johnson Nutrition

Mead Johnson MetabolicsParents’ Guide to PKUAn Informational Guide to DietaryManagement of Individuals with PKUThis booklet is intended by Mead Johnson to be provided to you by your healthcareprofessional as part of his or her care plan in the dietary management of PKU. Your healthcareprofessional is your primary source of information and advice. Always discuss with yourhealthcare professional any information you receive and any changes you wish to make.

PrefacePKU is an abbreviation for phenylketonuria, a metabolicdisorder which affects about 1 in 10,000 children. It is an inheriteddisorder which can be treated very successfully. We at Mead Johnsonhope this booklet will help you learn more about PKU.We put Parents’ Guide to PKU together because we know how“lost” you may be feeling right now. What is PKU? How did our babyget it? Will our child grow and develop normally? How will we dealwith this disorder? You are probably looking for answers to these andother questions. We hope that some of your questions about the recentdiagnosis of your child will be answered here.In Parents’ Guide to PKU, we have drawn on our experienceproviding metabolic formulas for children with PKU. Your experiencesand your child will not be exactly like other families, but we hope thatyou and your family can benefit from what we have learned. We havealso included the words of some parents who are truly living with PKUso that you might hear their experiences for yourself.For simplicity, we have alternated “he” and “she” when referring toyour child since both boys and girls will benefit from this information.Mead Johnson Nutritionals gives special thanks to The Children’s Hospital InheritedMetabolic Diseases Clinic (affiliated with University of Colorado Health Sciences Center)for their help in providing information contained in this booklet.2

Table of ContentsIntroduction 4What Is PKU? 4Will Our Child Grow and Develop Normally? 4How Did Our Child Get PKU? 5How Do We Know Our Child Has PKU? 7How Will We Manage Our Child’s PKU? 8The PKU Diet 8Regular Clinic Visits 8First Steps In Treatment 9How Will This Affect Our Family? 10What Can We Expect As Our Child Grows? 11Infancy: Birth to 12 Months of Age 11Toddlers: Ages 1 to 3 Years 12Preschoolers: Ages 3 to 5 Years 13Grade School: Ages 6 to 12 Years 13Adolescents: Ages 12 to 18 Years 14Maternal PKU: When Your DaughterIs Ready To Have Children 15Questions Parents Often Ask 16Tips For Parents 19Hints While Traveling 19Helping Your School-AgedChild With The Diet 20Glossary Of Terms Associated With PKU 21Where To Go For More Information 223

IntroductionWhat is PKU?PKU is an abbreviation forphenylketonuria, a metabolic disorderin which the affected personlacks an enzyme that breaks downa component of protein in foods.To understand PKU, we haveto start with amino acids—thebuilding blocks of proteins. Someamino acids are essential, whichmeans the body cannot makethem and they must be suppliedby the diet. Phenylalanine is anessential amino acid which ispresent in most protein-containingfoods; it is also converted by thebody into another amino acidcalled tyrosine. Phenylalanine isoften abbreviated to “Phe”(pronounced “Fee”). Bothphenylalanine and tyrosine areneeded for normal growth anddevelopment. The person withPKU doesn’t have the enzyme(phenylalanine hydroxylase) that thebody uses to make this conversionfrom phenylalanine to tyrosine.Because the body can’t get ridof the excess amounts of phenylalanine(Phe) in normal ways(ie, by converting it to tyrosine),phenylalanine builds up in theblood and other body tissues, andsome is converted to substancescalled phenylketones, which areexcreted in the urine. This processof the body trying to get rid ofexcess phenylalanine is where PKUgets its name: phenylketonuria orphenylketones in the urine. Thehigh level of phenylalanine,phenylketones, and low tyrosinelevels result in poor growth andmental development.Will Our Child Growand Develop Normally?With proper dietary managementand early identification,your child can grow and developnormally. Your child is likely todevelop at the same rate as otherchildren his age, to be equallyintelligent, and to do as wellin school.Without dietary treatment,your child could develop moreslowly and could become mentallyretarded. Many studies have showna relationship between the degreeof dietary control, blood Phelevels, and the child’s IQ, so itis very important to follow theinstructions you are givenconcerning your baby’s diet tomaintain “safe” blood Phe levels.PKU is a chronic disorder,which means your child will needto follow a special diet for all ofchildhood and into adulthood.The most healthy persons withPKU are those who control their4

lood phenylalanine levels for life.It is especially important that girlscontrol their blood phenylalaninelevels because high levels of phenylalaninein a pregnant mother’sblood can cause serious problemsfor a developing fetus. Remainingon the diet for life is stronglyrecommended for all individualswith PKU.How Did OurChild Get PKU?You are probably wonderinghow your child got PKU. You mayhave other children who do nothave PKU, and it’s possible thatno one in your family has everhad PKU as far back as anyonecan remember.PKU is a genetic disorder,which means it is inherited fromthe parents. To understand howyour child “got” PKU, it’s helpfulto know something about chromosomesand genes. Every cell inthe body contains 23 pairs ofchromosomes (a total of 46 individualchromosomes) which haveall the genetic information thebody needs. One chromosome ofevery pair is inherited from thefather, and one chromosome ofevery pair is inherited from themother. These chromosomes aremade up of genes which are linedup on the chromosomes like beadson a string. The genes are arrangedin pairs just like the chromosomesare. Genes work to determinephysical characteristics (such as eyecolor and hair color) and provide“instructions” for developing andmaintaining the body, such asmaking phenylalanine hydroxylase.In genetic terms, PKU is anautosomal recessive disorder.Autosomal means that it is notlocated on the “x” or “y” chromosomethat determines gender.Recessive means that both parentsmust contribute a non-workinggene for PKU in order for thechild to have PKU. If only oneparent passes on the gene forPKU, the child will not have anysymptoms of PKU, but will be a“carrier” and still be able to passthat gene along to his or her children.Since the parents are usually“carriers” of the disorder, they willhave no symptoms of PKU and maynot even know they are carriers.In fact, PKU may have beenpassed down silently through bothfamilies for many generations—that is, no one in either familymay have known they carry thegene. It’s only when two carriershave children together that inherita non-working copy of the genefrom both parents that the disorderis expressed with clinical symptoms.Although untreated PKUcan cause mental retardation, itdoes not indicate a family historyof mental retardation. PKU canbe very successfully treated, andchildren with PKU can grow anddevelop normally, both mentallyand physically.Figure 1 illustrates how PKUis inherited. For a child to havePKU, each parent must be a carrier5

of the disorder, which is shownas “Pp” in Figure 1. A carrier hasone working gene (P) for producingthe enzyme phenylalaninehydroxylase and one non-workinggene (p) which does not producethe enzyme, but no symptomsof PKU.In every pregnancy, the eggand the sperm combine to makea fetus. One of the mother’s genesfor a trait (P or p in this case) fromthe egg and one of the father’sgenes (P or p) from the sperm goto make the fetus. The inheritanceof genes is a completely randomprocess, and if the baby inheritstwo p genes, he will be born withPKU. This child (pp, in geneticterms) requires nutritional managementto keep excess phenylalaninefrom being toxic to his body.As shown in Figure 1, whentwo carriers for the non-workinggene have children together, thereis a one in four chance (25%) thatthey will have a child with PKU.Likewise, there is a 75% chancethey will have a baby who doesnot have PKU; this child may bea carrier (Pp) like the parentsor may have two working (PP)genes. These odds don’t meanthat a family of four childrenwill have one child with PKU,because the chances are thesame with every pregnancy.PpNon-AffectedCarrierNon-AffectedCarrierWith every child, the odds in thisexample are one in four of havingPKU.Because PKU is hereditary,everyone in the families of bothparents should know about thepresence of PKU. This will helpmake certain that all babies borninto the family are screened forPKU at birth. Families should talkwith genetic counselors for themost up-to-date information onthe genetic aspects of PKU.How Recessive Inheritance WorksppAffectedChildPpP=Working Genep= PKU GenePpPpNon-AffectedCarrierNon-AffectedCarrierPPNon-AffectedFigure 1: Two PKU (pp) genes areneeded for a child to be affected.Each child has a 25% chance ofbeing affected. If one parent is affectedby PKU, then each child has a 50%chance of being affected.6

How Do We KnowOur Child Has PKU?Children with PKU are firstidentified from elevated bloodphenylalanine levels detected withnewborn screening tests. Thesetests are convenient, inexpensive,and allow early identification ofseveral genetic diseases. PKUscreening is mandatory for allnewborns in the United Statesand in many other countries. Byscreening in the first days of life,infants with PKU can receivetreatment immediately. Promptdetection and treatment areextremely important becausemost problems associated withuntreated PKU can be preventedif treatment is started early.To perform the tests, a fewdrops of blood are taken from thebaby’s heel and absorbed onto apiece of special blotter paper.The blood is usually taken inthe newborn nursery.Several laboratory tests are usedto screen for PKU, the most commonof which is called the Guthrietest. This test uses a certain strainof bacteria which needs phenylalanineto live. If there is excessphenylalanine in the baby’s blood,as in a baby with PKU, the bacteriawill grow. The more phenylalaninethere is in the blood, themore the bacteria will grow aroundthe blotter paper. The amount ofbacteria can then be compared toestablished standards to determinethe phenylalanine level in the baby’sblood. Tandem mass spectrometryis also used in some states toscreen for PKU.If results of screening tests showelevated phenylalanine levels(positive), another blood sample iscollected and a repeat test is run toconfirm the results. Positiveresults on the screening testdon’t diagnose the child withPKU, but they do indicate a needfor further tests. More completeconfirmatory tests are done byyour baby’s doctor or a clinic thatspecializes in treating PKU.High levels of phenylalanine inthe blood can indicate yet anothertype of genetic disorder which issimilar to PKU, but extremely rare.It is important to distinguish thisgroup of patients from childrenwith PKU because they must betreated with certain medicationsin addition to a special diet. Theclinic doctors will perform severaltests on your baby to be sure thediagnosis of PKU was correct.In the 1930s, Fölling and othersidentified in severely mentallyretarded patients a condition ofhigh phenylpyruvic acid in theirurines. This was later shown to bedue to the patient’s inability toutilize phenylalanine. However, itwas not until the 1950s that dietscould be developed to treat the highlevels of phenylalanine in infants.Before simplified screening forPKU became available early in the1960s, infants with PKU oftenwere not treated with special dietsuntil their parents noticed the babywas not developing normally. Bythat time, brain damage hadalready occurred.The development of a simplesensitive test to pick up phenylalaninein the blood and an effectivediet resulted in the state-mandatedscreening program that picked upyour baby’s elevated phenylalaninelevels. Studies were carried out todetermine if and when the specialdiet could be discontinued. Theresearch showed that diet wasneeded for life to assure the infantreaches his or her maximummental abilities. Today, babies withPKU can develop as normally astheir unaffected siblings and go onto lead normal successful lives, aslong as the special diet prescribedis followed. Research continues tobe carried out looking for alternativesto diet. Until that goal isreached, special diets will be theonly solution to help preventmental retardation.7

How Will We Manage PKU?The PKU DietYour child’s special PKU dietis extremely important. Withoutdietary treatment, your child couldbecome severely retarded. Withcareful dietary treatment, yourchild can be healthy and developnormally.In the PKU diet your child willbe on, foods that contain proteinand are, therefore, high in phenylalanine(Phe) are typically excludedfrom the diet. These include cow’smilk, meats, eggs, cheeses, nuts,peanut butter, soy drinks, and tofu.Instead, your child’s diet will consistof a prescribed special medicalfood and low-protein foods.This prescribed special medicalfood is essential since protein andits component amino acids areneeded for normal growth anddevelopment. Nearly all proteinsare high in phenylalanine. Becausea person with PKU can’t breakdown phenylalanine to tyrosine,regular food protein will causethem to have too much phenylalanineand not enough tyrosine intheir blood. Therefore, infants andchildren need a protein source freeof phenylalanine but high in tyrosine.The special medical foodhas little or no phenylalanine, ishigh in tyrosine, and provides agood source of vitamins andminerals. Your metabolic clinicteam will prescribe the appropriatespecial medical food for your child.Because each child has a uniqueabsolute requirement for phenylalanine,the metabolic clinic teamwill prescribe a diet tailor-made foryour child. The prescribed specialmedical food, such as a dietarypowder from the Phenyl-Free ®family of special medical foods, isthe mainstay of management ofPKU. The metabolic clinic teamwill work with you to make sureyour child gets the appropriateamounts of special medical foods,as well as other foods, as your childgrows and develops. It is vitallyimportant for your child’s growthand mental development to followthe metabolic clinic’s direction onfeeding your child.Your child’s needs changeduring growing up. The metabolicclinic team will help you design adiet to provide all the calories,phenylalanine, protein, vitamins,and minerals your child needs togrow. The special medical food willnot supply all your child’s needs.As your baby grows and begins toeat solid foods, foods such as fruits,vegetables, and low-protein pastaswill be added to the diet. Thevariety of foods and dishes yourchild can enjoy is quite large.Recipes have been developedalready by other parents ofchildren with PKU. The metabolicclinic team will help you find theserecipes and ingredients.The diet for PKU is quitesimple to prepare once youunderstand what your child canand cannot eat. The metabolicclinic team will teach you how toplan your child’s daily meals. Theywill ask you to keep careful recordsof how much your child is eatingin order to balance this intake withthe amount of phenylalanine andprotein needed for growth andmental development. For yourchild to develop normally, the dietmust be maintained consistentlyand accurately. The metabolicclinic team will work closely withyou to help you in this goal.Regular Clinic VisitsMuch of your child’s treatmentfor PKU may occur at a clinic thatspecializes in this disorder, and youwill be asked to bring your childwith PKU to the clinic regularly.Your baby’s pediatrician will getreports of the clinic’s dietinstructions and your child’s bloodresults. In general, PKU clinicsdon’t handle illnesses unrelatedto PKU or give routine baby shots,so it’s important for you tohave a primary care provider or8

pediatrician for your baby’s othermedical care. The PKU clinic teamcan help you find a local pediatricianif necessary.The PKU clinic team willregularly need information sochanges in the diet can be madeto match what your child needsto grow and develop normally.This information includes recordsof your child’s food and specialmedical food intakes, height, andweight. The clinic will also wantto measure blood levels of phenylalanineregularly to make sure thatyour child has every chance ofnormal development. These visitswill give you an opportunity todiscuss any questions you may havewith the metabolic clinic’s team,and the team to share with you thelatest information on PKU.Just as in the treatment of anydisease, doctors and nutritionistsvary in their procedures for managingphenylketonuria. A particularclinic may differ from the followingdescription, but there willprobably be many similarities.First Steps in TreatmentFollowing the initial positiveresult for PKU, your baby will bestarted on a diet very low inphenylalanine to get his bloodphenylalanine level down quickly.This may take several days. If youare breastfeeding, the metabolicclinic doctor will ask you not tobreastfeed your baby during thistime. However, you are encouragedto continue breastfeedingyour child after his blood phenylalaninelevels are lowered, if youwish. Your baby’s metabolic clinicteam will help you plan a diet thatincludes breast milk.Next, your baby will be put ona prescribed diet, and blood levelsof phenylalanine will be checkedfrequently to be sure they aren’t toohigh or too low. Growth anddevelopment will be carefullyfollowed as well. Frequent visitsto the clinic will be required tosee how your baby is progressing.Many PKU clinics have ateam approach, and you may haveappointments with several membersof your baby’s treatment teamon the same appointment day. Thenutritionist will probably be yourprimary contact—he or she willmonitor the therapy, adjust thediet prescription as necessary, andprovide advice when problemsarise. A physician will examineyour baby and help with problemsolving.A nurse will weigh andmeasure your child to be sure thediet is meeting growth needs. Asyour child gets older, a psychologistmay evaluate him periodicallyto make sure his psychologicaldevelopment is normal. A socialworker or counselor may meet withyour family to help you adjust toliving with PKU.The services the clinic providesare essential to you to maximizeyour child’s development. Be assuredthe clinic team members are veryinterested in the health and developmentof your child. You willwant to work closely with them inorder to assure your child’s maximumprogress. This will includekeeping accurate records of yourchild’s food and special medicalfood intake, cooperating with theclinic in getting the required numberof blood tests, and keepingclinic appointments. Providing therequested blood test, keeping clinicappointments, and following theclinic’s diet for your child areessential. The healthy developmentof your child depends onthese steps.9

What Can We ExpectAs Our Child Grows?A baby with PKU who hasbeen treated from the first monthof life can be expected to growand develop much like any otherhealthy infant. Keep in mind thatall babies develop at their own rate,and even in the same family a childmay start walking or talking at adifferent age than a brother orsister did.Always feel free to discussquestions about your baby’s developmentwith your physician andthe staff at your child’s PKU clinic.Clinic specialists are available tohelp you manage your child’s dietthroughout the stages of development,and you can benefit fromtheir experiences with other PKUchildren. You may even be able tofind a support group of PKUfamilies in your area, which couldhelp you and your child discovercreative ways to deal with PKU.Since no child is just likeanother, what follows is only aguide to helping achieve normaldevelopment. It gives you an ideaof what your baby might be doingnow and what you can lookforward to in the future.Infancy: Birth to 12 Monthsof AgeBabies change very rapidlyduring the first year of life. Asparents, you will want to pay closeattention to your baby so you don’tmiss any new developments.Watch your baby—not becauseof the PKU—but because it’s funto watch her develop.By 3 months of age, your babywill be more responsive to peopleand will smile and coo in responseto your smiling and talking.Increased muscle strength andcoordination allow easy movementof legs and arms. When lying onhis stomach, your baby will lifthis head and shoulders to watchwhat is going on in the room. Bythis time, you will probably feelcomfortable mixing the specialmedical food and keeping trackof your baby’s formula or breastmilk intake.At 4 to 6 months, you will beintroducing pureed foods. Yourclinic’s nutritionist will probablysuggest starting with purees ofvegetables and fruits. The additionof solid foods at this stage maymake the diet more difficult foryou until you’re used to determiningthe amount of phenylalaninein food.Most 6-month-olds havedoubled their birth weight. Bettercontrol of back and neck musclesmeans your baby will be able to sitwith only minimal support. Yourbaby will enjoy playing with hishands and simple toys. Mostthings that your baby can holdwill go straight into his mouth,including foods that are withinreach. You will want to have lowproteinfoods available so yourbaby can experiment with selffeeding.Low-protein foods withtexture will help support chewingand oral motor development andto respond to hunger withoutaffecting blood Phe levels.By 12 months, your baby willhave tripled his birth weight andwill be able to get around quitewell by crawling or walking whileholding onto furniture. He willplay more with toys and be ableto pick up the tiniest things leftwithin his reach. By this age, manybabies will also be saying a fewsimple words.As your baby grows, her growthrate will decrease. Because she isgrowing slower, she will naturallyeat less. Work with your metabolicclinic team to balance your child’sdiet with her appetite and hersocial and physical needs. You willwant to establish a pattern of mealsso she will begin to understandhunger and satiety. Feeding maybecome more difficult. When this11

occurs, feed the special metabolicproduct first followed by the lowproteinfoods your baby likes.Your baby is also developing socialskills. You will need to balanceyour approval and disapproval ofyour baby’s behavior. Food andfeeding should not become a placewhere excessive playing, pleading,or anger occurs. You could establisheating as a good area for yourbaby to assert her emerging senseof will.By the time your child reaches12 months of age, you will wantto keep forbidden foods well outof reach. He will be much moreactive and able to explore. Youwill want to make sure that nodangerous household materialsare accessible to be picked upand placed in his mouth.Toddlers: Ages 1 to 3 YearsBy 18 months of age, yourchild will probably be able to walkalone, drink from a cup, and tryto feed himself. He will try to“talk” and will understand theword “no.” His decreased appetite,desire to feed himself, and highlevel of activity will require attentiveparenting. It is important toavoid these tensions as much aspossible by positive developmentalapproaches.Establishing regular meals andsnack times, allowing extra timefor self-feeding, and tolerating theresulting mess can help yourtoddler’s motor and social skills.Feed the special metabolic productfirst to assure adequate intake ofprotein. Try new low-protein foodsand recipes to make mealtimesmore interesting for your baby.Your toddler will enjoy fingerfoods. By offering finger foodslowest in phenylalanine for feedingherself, it will simplify the task ofcalculating the amount of phenylalanineconsumed and enable thechild to have “more.”Two and 3 year olds are quiteactive. They progress from walkingup and down stairs with help tounlocking the front door andgoing for a “walk” on their own.The 2 year old can put twowords together and can make hiswants known. The 3 year old usessentences of several words andcan point to his eyes and ears.The older toddler can go fromhappy to sad and back again at amoment’s notice. This doesn’tmean your child’s phenylalaninelevels are high, but that he isacting his age. The desire forindependence and the tantrumsthat go along with this age arealso typical and are not the resultof PKU. If you do have anyconcerns, however, please discussthem with your clinic specialists.By 2 to 3 years, your child may12

know there are foods he can andcannot have, and you should startteaching him about his diet. Butrealize that a 3 year old does notunderstand why some foods arenot good for him (especially whenhe sees other people eating them),and he cannot be expected on hisown to refrain from eating them.Many families establish an “askbefore you eat” rule. Develop anapproach to understanding “yes”or “no” but not “maybe.”Preschoolers: Ages 3 to 5 YearsYour 3 or 4 year old isobviously no longer a baby. Hemay ride a tricycle and wash hishands unassisted. Tantrums andstubborn behavior can continuethrough 3 and 4 years of agebecause these children often wantto do more than they are capableof doing and become frustrated.This frustration (not their PKU)may lead to whining and crying.Throughout the preschoolyears, your child will graduallybecome better able to understandsome things about his diet. Try toanswer as many of his questions asyou can, even if it seems like youare answering the same questionsover and over. It is very importantthat you are consistent. Generally,your child will be happiest with aschedule. Promote formula firstand consistency in foods andportion size. Remember, that asyour child grows, he will havemore and more opportunities tomake inappropriate food choices.Good eating patterns should befirmly established before opportunitiesto make inappropriate foodchoices present themselves.At age 3, your child can beginto learn about PKU as well as hisspecial diet, and he should understandthe idea of “yes” foods and“no” foods. Reading books togetherfor children with PKU can helpyou begin to teach your child aboutwhy he must follow a special diet.(See bibliography for resources.)As your child is able, you maywant to allow him to choose someof his foods and help with theirpreparation. Five and 6 year oldswill have a general idea of what isallowed on their diet but probablywon’t be able to decide if foodsthat are new to them are allowed.By 5 or 6 years, your child will bemore cooperative about his diet,particularly if he has learned thatyou won’t bend the rules.Grade School: Ages 6 to 12 YearsBy grade school, your child willbe mastering skills that she begandeveloping at earlier ages. Shewill need less help taking care ofherself and gradually will becomeindependent in eating, dressing,and bathing. Your child may like13

to ride a bicycle and visit withfriends at their homes.The thought processes of thegrade-school child are constantlydeveloping, and she will understandtime periods and how to seethings from another’s perspective.She will learn to deal with morethan one detail at a time and torelate one idea to another. At thisage, your child will reason and usesimple logic and should be encouragedto apply new math skillsto her diet as she learns them.Children in early elementaryschool should begin to keep trackof their phenylalanine intake, as wellas help with making their formula.It is reasonable and necessary toinvolve your child more and morein his diet as he reaches school age.By later elementary school, yourchild should understand whatlevels of blood phenylalanine areacceptable and should be trackinghis own levels. As your childunderstands more about PKU andis more involved in his diet, youcanprovide opportunities for him tomake decisions for himself,including calculations of Phe infoods. Parents should work withtheir children with PKU to choosefoods and plan menus, record theirdiets on the diet records, and dotheir own finger sticks for bloodsamples. The more involved yourchild is in his treatment, the morelikely he will have the knowledgeand skills to make more appropriatechoices independently. Childrenthis age prepare formula and takeresponsibility for drinking it.Adolescents: Ages 12 to 18 YearsYour adolescent may want tobe independent, but he still needsparental guidance and direction.At this stage, your child should bedeveloping responsibility for hisown diet and food choices. This isgood training, not only for thechild with PKU, but also for allchildren.Most adolescents are fullycapable of understanding bothPKU and the diet. Your teenagerwill be able to read and write withease and to perform math calculationsas required to manage hisdiet. He should be keeping hisown diet records and beingresponsible for clinic appointments.One aspect of adolescencethat will make dietary compliancemore difficult, however, is theneed for peer approval. Manyadolescents don’t want to be seenas any different from their friends,and having PKU can make themfeel different. These concerns maymake it difficult for them to makeappropriate food choices. Continueto actively parent your adolescent.Provide positive support and helphim develop strategies for dealingwith his peers—your child has noreason to feel different if he hasthe skill, knowledge, self-esteem,and parental support you haveprovided.14

Maternal PKU:When Your Daughter IsReady To Have ChildrenIn the past, children with PKUwere usually permitted to discontinuetreatment (and have elevatedblood phenylalanine levels) beforeadolescence. However, severalstudies have shown that childrenwho discontinue treatment or havehigh Phe levels have more difficultieswith thinking processes andmath skills. Other studies havefound that elevated blood phenylalaninelevels in older patientswere associated with behavior andlearning problems which werereversed when the patientsreturned to more restricted diets.For these reasons, most clinics arenow recommending that personswith PKU remain on the diet forlife. This “diet for life,” whichmeans good Phe levels for life, isa strong recommendation—discontinuing treatment is notadvised at any age.As they begin their menstrualcycles, girls with PKU shouldunderstand the effect PKU canhave on developing babies.High blood levels of phenylalanineare very damaging to adeveloping fetus.Researchers have found that, asthe mother’s blood phenylalaninelevels increase, her chance ofhaving a baby with an abnormallysmall head and mental retardationalso increased. Incidence of lowbirth weight and congenitalheart disease appears to increasemarkedly when serum phenylalaninelevels are consistently abovethe “good level.” In women whohave not stayed on the diet, it isnecessary to reinstate dietarytherapy before conception. Theprognosis for having a normalchild is better, but it is criticalthat diet therapy begins beforeconception. The fetus is verysensitive to high levels ofphenylalanine. The early monthsof pregnancy are believed to bethe most crucial for normaldevelopment.For these reasons, it’s veryimportant that women withPKU follow their phenylalanine-restricted diet before conceivingand throughout pregnancy.Because it’s so difficult to go backto the diet after being off it, it isespecially important that womencontrol their blood phenylalaninefor a lifetime.15

Questions Parents Often AskDid something happen duringmy pregnancy that could havecaused my baby to be bornwith PKU?No. PKU is inherited fromboth parents. Only when theuniting sperm and egg bothcontain the gene for PKU willthe baby develop this condition.How can you tell who is acarrier of PKU?When a child is born with PKU,we know that both parents are carriersfor the altered PKU gene.Consult with your genetic counselorabout determining who else inyour families may be carriers.Siblings of a child with PKUhave a 50% chance of being carriersfor PKU. Therefore, they maywant to have carrier testing doneon themselves before they begin afamily. If they know they are carriersof PKU but are unsure of thePKU status of their spouses, theywill want to be certain that earlyscreening is done on any childrenthey may have.If we have one child with PKU,how will this affect the possibilityof having future children withPKU?When both parents are carriersfor the altered gene, there is a onein four chance with each pregnancythat PKU will occur. Therefore,you have a 25% chance of havinga baby with PKU each time youare pregnant.How many people in the generalpopulation are carriers of PKU?One in 50 to one in 70. Thisnumber is slightly higher in somepopulations and lower in others.Every person carries several geneswhich, like the PKU gene, cancause a variety of inherited disorders.Carriers for the altered PKUgene are not different from thegeneral population nor do theyhave any abnormalities resultingfrom being a carrier.What will happen to my childwith PKU when she marriesand has children?If the father is a carrier for thealtered PKU gene, a child theyhave would have a 50% chance ofhaving PKU. If the father is nota carrier, none of their childrenwould have PKU, but all childrenwould be carriers.What is “Maternal PKU?”This is the term given to thespecial problems that can occurwhen a woman with PKU haschildren. Women with PKU needto understand that if they becomepregnant when their blood phenylalaninelevels are high, there is agreater chance the baby may beborn with birth defects or developmentaldelays. Being on a very lowphenylalanine diet prior to conceptionand throughout pregnancyreduces the risk of these problems.If we have a child with PKU inthe family, how will this affectthe lives of our other children?Having a child with specialhealth needs causes some changesin attitudes and family routine.For example, eating habits mayhave to be adjusted, and the childwith PKU may seem to get moreattention than the childrenwithout PKU. Parents have to be16

careful not to center their attentionon the child with PKU, particularlyat mealtimes. Older brothers andsisters may try to “mother”the child with PKU, and siblingsmay even taunt the child withfoods he cannot eat. Parents willhave to make it very clear thatsuch behavior is not acceptable.What is the PKU diet?It is a diet low in phenylalanine,which is the amino acid that thechild’s body cannot use properly.The specific diet for your child willbe specially designed by your metabolicphysician and nutritionist.The diet is designed to meet yourchild’s individual needs for growthand development. The dietincludes a protein substitute, suchas Phenyl-Free ® 1 or Phenyl-Free 2dietary powder, which provides themissing protein but has little or nophenylalanine. In addition to theseproducts, patients are given a prescribedspecific amount of phenylalaninefrom breast milk, regularinfant formula, or solid foods toprovide enough phenylalanine forgrowth. Measured amounts offruits, vegetables, cereals, lowproteinbreads, pasta, and specialdesserts are added to the diet as thechild gets older.Is the diet expensive?The formula costs more thanregular infant formula because itis specially designed for medicalpurposes. However, because of theimportance of formula for yourchild’s mental and physical development,most health insuranceplans pay for it. In some states, thespecial medical formula is providedby the State Department of Health.In other states, these products areprovided on a sliding fee scale,based on ability to pay. The socialworker, nutritionist, or nurse atthe PKU clinic can usually helpidentify a payment method.Can I breastfeed mybaby with PKU?Yes. Breast milk is lower inphenylalanine than either infantformulas or cow’s milk, and it canprovide the supplemental amountsof phenylalanine required for yourbaby’s growth when used with aspecial phenylalanine-free formulasuch as Phenyl-Free 1. Many newbornbabies with PKU can be fedwith breast milk and phenylalanine-freeformulas and still keeptheir blood levels in an acceptablerange. All babies with PKU musthave their diet intake and bloodphenylalanine levels monitoredclosely. You’ll want to discuss yourdecision to breastfeed your babywith PKU with your baby’sdoctor and dietitian.Why are diet diaries kept?Diet diaries are records of foodintake which serve as guides for theclinic team when adjusting yourchild’s diet. These diaries are anecessary management tool. It isthe only way for the nutritionist toknow exactly what your child hasbeen eating or drinking so thatappropriate changes can be madeto assure the proper levels ofblood phenylalanine.How long will my child withPKU be on the diet?Medical experts state thatmaintaining the restricted dietthroughout life is preferable. Datafrom the National CollaborativeStudy of Children Treated for PKUshow that intellectual ability andacademic achievement in schoolare negatively affected when bloodlevels are persistently high beforethe age of six years. Other studieshave shown that children whomaintained acceptable levels ofblood phenylalanine through age10 had higher IQ scores thanchildren who didn’t have low Phelevels. A “diet for life” approach iscurrently recommended.17

What happens if my child withPKU refuses to eat part or all ofhis prescribed diet?If this goes on for only afew days, it is not a problem.However, if the child gets into apattern of eating only one kindof food, the prescribed amountsof food and formula may not beingested. Don’t worry if this goeson for a day or two. If youdevelop a pattern of specialmetabolic products along withregular meals, your child will probablynot refuse to eat for a longerperiod than one or two days. If shedoes, it’s a good idea to check withthe metabolic clinic team to ruleout a health problem requiringtreatment. Call your PKU clinicfor help in adjusting the diet duringthese times, rather than tryingto adjust the diet yourself. Staff atthe clinic will suggest other ways toget your child to eat and to assureadequate intake in cases of fever,vomiting, and/or diarrhea, or otherchildhood diseases which result inloss of appetite.Will my child get sick if he doeseat some high-protein food?No. There may be an elevationin blood phenylalanine levels thatwill gradually decrease if furtherPhe intake is restricted. However,frequently high levels of bloodphenylalanine can affect yourchild’s development, even thoughhe may not show obvious physicalsigns of toxicity.What are “good” bloodphenylalanine levels?Most clinics generally regardthe range of 2-6 mg/dL as “good”blood phenylalanine levels. Pleaseconsult your clinic about what isa good level for your child.What causes blood phenylalaninelevels to go up?In most cases, elevated phenylalaninelevels may indicate thatyour child is eating more phenylalanine-containingfoods than heshould eat to meet his growthneeds. If your child is not gettingenough of his special metabolicproduct, his body will break downmuscle and other protein stores,thereby releasing phenylalanineinto the blood. Illness can alsocause this breakdown and makeblood phenylalanine levels rise. Ifyour child is growing rapidly, hemay need extra amounts of food orspecial metabolic product, whichcan cause a change in bloodphenylalanine.What causes blood phenylalaninelevels to go down?When a child’s diet is changedfrom regular food to a phenylalanine-restricteddiet, levels of bloodphenylalanine will go down.18Generally, when a child’s prescribeddiet is appropriate for herage and rate of growth, and thediet is closely adhered to, phenylalaninelevels should be within thedesired range. A level below therange suggests your child is noteating all her “Phe foods.”Will my child become retarded?With early dietary treatment,careful dietary management, andresulting good blood Phe levels,the chances are very good that yourchild will grow and developnormally.Will my child with PKU lookor act differently than otherchildren?If he has received early treatmentand adhered to the dietprescribed by your metabolic clinicstaff, your child with PKU shouldnot look or act differently thanother children.Will my child be sickly?Having PKU will not causeyour child to have poor health.Will my child be able to go toregular schools?If your child is treated early andcarefully, his PKU will not preventhim from attending regular schools.

Tips For ParentsThe following tips are compiledfrom the experiences ofmany families living with PKU.As you become more comfortablewith the PKU diet, you likely willdiscover other ways to effectivelymanage the disorder. You shouldalways discuss ideas with the clinicfirst before making any changes.• Remember that you aren’tmanaging the diet of yourchild alone. The whole family,as well as neighbors andfriends, should be instructedabout diet restrictions.• Estimate how long yoursupply of formula will last,then order early so you don’thave to worry about runningout. Remember that you maynot be able to go out to thestore and buy an extra can ofPhenyl-Free ® 1, Phenyl-Free 2,or any other PKU formula ifyou run out.• Don’t change too many thingsat one time during the transitionfrom pureed foods to selffeeding.Work in consultationwith your clinic nutritionist sothis transition can be completedeasily and in a stepwise manner.• Keep in mind that duringillness or fever, bloodphenylalanine levels mayrise. Consult your clinic forguidance on how to minimizethis effect of illness.• Include your child’s needs inthe family meal plan. Try tomake meals containing foodsthat your child can eat.• Keep reconstituted products ina well-marked container that isdifferent from any other containerin the refrigerator sothat your child can easilyidentify “her” milk substitute.• Involve your child with PKUin the management of his owndiet when possible. This couldinclude helping to mix his formula,making his sandwich forlunch, or making treats from alow-protein cookie or cakerecipe.• Be consistent in your approachto the diet. A matter-of-factbut firm attitude will helpyour child adjust more easilyto diet restrictions. Keep inmind that all children testtheir parents, and your childwith PKU probably will be nodifferent. When diet restrictionsare followed regularly,forbidden foods may lose someof their appeal.• Avoid the habit of snackingcontinuously. If your childneeds to eat between meals,make that snack an event of itsown which you or a caregiversupervises. You may want tohave a “tea party” when yourchild wakes up from his afternoonnap. He will be lessinclined to help himself tosnack foods when he knowsthere will be a defined snacktime.• Don’t let your child sampleunallowed foods just to tastethem. Your child is better offnever having tasted foods that,once tried, may become evenmore appealing.• Never let your child know youfind the smell or taste of theformula objectionable.Hints While Traveling• Always take morePhenyl-Free 1, Phenyl-Free 2,or any other PKU formulathan you will need when youleave home, since it may bevery difficult for you to get itin another state or country.• Put premeasured amounts offood into small containers tosimplify calculating yourchild’s intake.19

• Measure the Phenyl-Free ® 1,Phenyl-Free 2, Phenyl-Free 2HP,or any other PKU formula intoindividual baggies or other smallplastic bags. You may find that asmall shaker works well for mixingthe products.• Once your child is eating foodsfrom the table, you can ordervegetables and fruit for him atrestaurants so he feels like eatingout is a treat.• Always carry low-phenylalaninesnacks, such as fruit, low-proteincookies, and candy. If your familyhas ice cream, get a non-milk,iced popsicle for your child withPKU.Helping Your School-AgedChild With The Diet• Teach your child how to dealwith questions about his dietfrom classmates. Think up goodanswers together before he startsschool.• Be sure your child’s teachers andlunchroom supervisor know ofthe diet for PKU and its importanceto his health. Most schoolpersonnel will be very happy tohelp. It may be useful for you togive the teacher a guide to whatkinds of snack foods your childcan have. Children often bringcupcakes or cookies to school tocelebrate birthdays or other holidays,and if your child can alsohave a special treat then he won’tfeel so different from his friends.• With some practice, you can helpyour child pack a lunch thatlooks like other kids’ lunches. Ifyou put cold formula in an insulatedlunch bag in the morning,it will usually stay cold untillunch time. Measure out thefoods your child should eat andpack these in small containers orbaggies. Low-protein bread forsandwiches, raw vegetables, fruits,and low-protein cookies can helphis lunch look “normal.” If yourchild knows to bring home anyuneaten foods from his lunch,you can keep better track of whathe needs for supper to meet hisdaily requirements.• Encourage your child to participatein school activities, eventhough arrangements may haveto be made for meals. The dietfor PKU should be treated as asmall inconvenience in an otherwisenormal life.• Develop the habit of treatingeach day as important to thehealth of your child. In additionto keeping a 3-day diet recordbefore blood tests, it is helpful tokeep a daily food diary. This willhelp you stay in the habit ofrecording your child’s diet. Aspiral-bound notebook kept inthe kitchen works well for thispurpose, and you can also note ifyour child is sick. Then, when hisblood level is high, you can goback through the food diary andtry to determine what caused it.• Teach your child the need to beaware of what she eats and beconsistent in drinking the specialmetabolic product. Help yourchild learn to make appropriatefood choices.20

Glossary Of TermsAssociated With PKUAmino acids are building blocksof proteins. Phenylalanine and tyrosineare amino acids. Some aminoacids are made by the body, but“essential” amino acids are not andmust be supplied in the diet. Phenylalanineis an essential amino acid.Autosomal recessive is a form ofinheritance requiring the presence oftwo genes for a trait in order for theindividual to show the trait. Personswith only one of an autosomal recessivegene pair are carriers of the traitbut are unaffected by the trait.Blood levels of phenylalanine aredetermined by tests done on bloodafter it is drawn from the heel, toe, orfinger. Blood levels of phenylalanineshould be in the range of 120-360umol/L (2-6 mg/dL).Collaborative study is a researchstudy on PKU. Because no one clinicin the country has enough patientswith PKU to answer all the questionswe have about the disorder, severalmajor medical centers collaborated ingathering data to learn more aboutPKU and improve treatmentmethods. This long-term projectdetermined much of what we nowknow about PKU, and researchcontinues at many PKU clinics.Enzymes are proteins responsiblefor causing or speeding up biochemicalreactions without being alteredthemselves by the reactions. Theenzyme phenylalanine hydroxylasecauses phenylalanine to be brokendown into tyrosine.Equivalent or exchange is ameasured amount of food, such ascereal, vegetable, or fruit, that hasa certain amount of phenylalanine.Some clinics use an “exchange”system to calculate intake ofphenylalanine. An “exchange”contains approximately 15 milligramsof phenylalanine. Patients on dietsfor treatment of PKU should eat alimited number of exchanges per day,determined in consultation with theirnutritionist and based on their sizeand growth needs.Genetics is the study of howcharacteristics are inherited. Genescontain information the body uses toproduce a specific trait or to performa particular body function.Growth measurements help youand the PKU clinic team know thatyour child is growing properly. Thesemeasurements are made at varioustimes for all children, not just forchildren with PKU. They typicallyinclude measures of your child’s height,weight, and head circumference.Guthrie test is a blood test usedin screening for PKU; newbornscreening is mandatory in the UnitedStates. It does not actually diagnoseyour child with PKU, but it indicatesto the physician that your child has ahigh probability of having PKU.Further tests are needed to make adefinite diagnosis.Hyperphenylalaninemiais a term meaning high levels ofphenylalanine in the blood. It21is a group of disorders in whichelevated blood phenylalanine levels area primary characteristic.Phenylalanine is one of severalamino acids that make up proteins.A certain amount of phenylalanineis needed for normal growth anddevelopment. Because the bodycannot make phenylalanine, it mustbe supplied in the diet. Phenylalanineis an “essential” amino acid.Phenylketonuria (PKU) is aninherited disorder in which the bodylacks the enzyme needed to convertphenylalanine to tyrosine. In PKU,excess phenylalanine accumulates inthe blood and tissues and can damagethe brain and nervous system ifleft untreated.Tyrosine is an amino acid whichis needed for normal growth anddevelopment. It is typically madeby the body from phenylalanine, butthe person with PKU can’t make thisamino acid and must get it from hisdiet. Tyrosine is present in phenylalanine-freeformulas suchas Phenyl-Free ® 1, Phenyl-Free 2,and Phenyl-Free 2HP.

Where To Go For More InformationDiet ManagementA Babysitter’s Guide to PKU.Trahms CM, Cox C. Available fromthe PKU Clinic at the University ofWashington, Seattle, WA. Telephone:(206) 685-3015.Finger Foods are Fun. Trahms CM,Cox C, Luce P, Padgett D. Availablefrom the PKU Clinic at theUniversity of Washington, Seattle,WA. Telephone: (206) 685-3015.Games that Teach: Learning byDoing for Preschoolers with PKU.Trahms CM, Cox C, Luce P.Available from the PKU Clinic atthe University of Washington, Seattle,WA. Telephone: (206) 685-3015.New Parents’ Guide to PKU.Trahms CM, Luce P. Available fromthe PKU Clinic at the University ofWashington, Seattle, WA.Telephone: (206) 685-3015.A Teacher’s Guide to PKU.Kaufman M, Nardella M.Office of Nutrition Services, ArizonaDepartment of Health Services,1740 W. Adams Street,Phoenix, AZ 85007.Cookbooks & Food ListsChef Lophe’s Phe-NominalCookbook. Barr LA, Trahms CM.Available from the PKU Clinic atthe University of Washington,Seattle, WA.Telephone: (206) 685-3015.Low Protein Bread Machine Bakingfor PKU. Schuett VE. 92 recipes forlow protein bread baking using breadmachines. See www.pkunews.org forordering information.Low Protein Cookery for PKU,2nd edition. Schuett VE. Over450 recipes for the PKU diet withphenylalanine, protein, and caloriecontent; suggestions for managingthe diet. See www.pkunews.org forordering information.Low Protein Food List for PKU.Schuett VE. Over 3,000 foods(including brand names) withphenylalanine, protein, and caloriecontent. See www.pkunews.org forordering information.Making the Change from High Pheto Low Phe: Changing recipes tofit your low phenylalanine mealpattern. Fink KJ, Trahms CM.Available from the PKU Clinic atthe University of Washington, Seattle,WA. Telephone: (206) 685-3015.Creative Family Cooking.The Mid Atlantic Connection forPKU and Allied Disorders.P.O. Box 6086,Lancaster, PA 17607.General InformationCoping with PKU: results ofnarrative interviews with parents.Awiszus D, Unger I. Euro J Pediatr.1990;149(suppl 1):S45-51.Intellectual development in12-year-old children treated forphenylketonuria. Azen CG, Koch R,Friedman EG, Berlow S, Coldwell J,Krause W, et al. Am J Dis Child.1991;145(1):35-39.After a positive Guthrie—what next? Dietary managementfor the child with phenylketonuria.Clark BJ. Euro J Clin Nutr.1992;46(suppl 1):S33-39.Intelligence in mild atypical PKU.Costello PM, Beasley MG, TillotsonSL, Smith I. Euro J Pediatr.1994;153(4):260-263.Breast-feeding in the managementof the newborn withphenylketonuria: a practicalapproach to dietary therapy.Greve LC, Wheeler MD, Green-Burgeson DK, Zorn EM. J Am DietAssoc. 1994;94(3):305-309.Maternal PKU collaborative study:the effect of nutrient intake onpregnancy outcome. Matalon R,Michals K, Azen C, et al. J InheritMetab Dis. 1991;14(3):371-374.Updated in 1996.Recommendations on the dietarymanagement of phenylketonuria.Report of Medical Research WorkingCouncil Working Party on phenylketonuria.Arch Dis Child.1993;68(3):426-427.22

For ordering information, call 800-BABY123 ororder online at www.store.enfamil.comLF870 REV 2/07©2007 Mead Johnson & Company