The Challenges Of Testing For And Diagnosing Porphyrias

Communiqué
November 2002
AVolume 27
Number 11
Features
The Challenges of Testing
For and Diagnosing
Porphyrias
Inside
Ask Us
Abstracts of Interest
Calendar
Test Updates:
• Cobalt Serum
Specimen Correction
• Metanephrine/
Normetanephrine Test
Adds Hypertensive
Reference Range
• Trichophyton Test Title
Change
W• Xanthine, Hypoxanthine,
Purine, and Pyrimidine
Move to LC-MS/MS
New Test
Announcements
• Chlamydia trachomatis
by Nucleic Acid
Amplification
• C trachomatis/N
gonorrhoeae by Nucleic
Acid Amplification
• Hereditary Pancreatitis,
Blood
• Neisseria gonorrhoeae
by Nucleic Acid
Amplification
• Postmortem Screening,
Bile/Blood Spots
• Testosterone, Total and
Bioavailable, Serum
Communiqué
Stabile Building
150 Third Street SW
Rochester, Minnesota 55902
1-800-533-1710
communique@mayo.edu
A M a y o R e f e r e n c e S e r v i c e s P u b l i c a t i o n
The Challenges of Testing For and
Diagnosing Porphyrias
The porphyrias are a group of inborn errors of
metabolism resulting from defects in the heme
biosynthetic pathway. Enzymatic deficiencies
resulting in the accumulation and excretion of
intermediary metabolites cause characteristic
clinical manifestations, which include
neurological and psychological symptoms
and/or cutaneous photosensitivity. Although
these disorders have genetic causes,
environmental factors may exacerbate symptoms,
which significantly impacts the severity and
course of disease. Early diagnosis coupled with
education and counseling of the patient
regarding the nature of the disease and
avoidance of precipitating factors are important
for successful management.
Photo 1. This patient’s hands demonstrate the
cutaneous photosensitivity that is associated with the
cutaneous, nonacute porphyrias. The chronic nature
of the lesion results in scarring.
Heme Biosynthetic Pathway
The heme biosynthetic pathway (Figure 1, page 3)
consists of 8 enzymes. The first and last 3
enzymes in the pathway are localized in the
mitochondria, and the intermediate enzymes
function in the cytosol. The formation of heme
begins with the condensation of glycine and
succinyl-coenzyme A to 5-aminolevulinic acid.
(5-aminolevulinic acid is also referred to as deltaaminolevulinic
acid, δ-aminolevulinic acid, and
aminolevulinic acid. It will be abbreviated as
ALA in this issue.) This is followed by a series of
enzymatic reactions that convert ALA to
porphobilinogen (PBG) and then to the various
porphyrinogens. Finally, iron is inserted into
protoporphyrin by the enzyme ferrochelatase,
forming heme.
The production of heme, a metalloporphyrin
containing iron, occurs in all metabolically active
cells. The majority is formed in erythropoietic cells
where it is incorporated in hemoglobin. Hepatic
tissue also produces a significant amount for use in
myoglobin and various heme-containing enzymes
including cytochromes, catalases, and peroxidases.
Heme that is not immediately utilized in a
protein complex is metabolized to bile pigments.
Each porphyria is caused by a specific enzyme
deficiency involved in the heme biosynthetic
pathway. Consequently, clinical symptomology
results from the accumulation of porphyrinogens,
porphyrins, and their precursors, which are formed
prior to the enzyme defect. Depending upon the
primary site of accumulation, porphyrias have
been classified as either erythropoietic or hepatic.
Cutaneous, Nonacute Porphyrias
The nonacute porphyrias include porphyria
cutanea tarda, hepatoerythropoietic porphyria,
erythropoietic protoporphyria, and congenital
erythropoietic porphyria. These disorders are
characterized by chronic dermatologic
symptoms. While cutaneous photosensitivity is a
common feature among the nonacute porphyrias,
other associated clinical and biochemical
features, inheritance patterns, and medical
management remain unique for each. (See Photos
1 and 2.)
www.mayo.edu/mml/communique.html

epidermis
papillae
vessels
thickened basement
membrane zone
dermis
Photo 2. This slide shows the thickened vessels, visible as
bright-green donut shapes, and the thickened basement
membrane zone that are characteristic of a diagnosis of
porphyria.
Porphyria Cutanea Tarda
Porphyria cutanea tarda (PCT) is the most common
porphyria and is most amenable to treatment. It is unique
in that it may be an acquired (sporadic, type I) or an
inherited (familial, types II and III) condition. About 75%
of patients have type I PCT. In these cases, symptoms are
precipitated by complications from liver diseases, such as
hepatitis C and hereditary hemochromatosis, or by
environmental exposures including certain medications,
estrogens, alcohol abuse, iron overload, smoking, and
occupational exposures to polychlorinated cyclic
hydrocarbons. Historically, outbreaks have been caused
by toxic exposure to certain organic chemicals.
Observed less commonly is familial PCT. It is estimated
that 25% of patients are affected with this autosomal
dominant condition. In type II PCT, uroporphyrinogen
decarboxylase activity is approximately 50% of normal
in all tissues, while in type III the enzyme is deficient
only in hepatic cells. In the absence of a positive family
history, type III PCT is virtually indistinguishable from
the sporadic form.
PCT is characterized by photosensitivity and skin fragility.
Patients experience blistering lesions in sun-exposed areas
resulting in cutaneous thickening and scarring. The face,
neck, forearms, and backs of hands are areas most often
affected. Minor trauma may also trigger lesions. Twothirds
of patients experience hypertrichosis (excessive hair
growth) on the face, and less frequently on the ears and
arms. Approximately half of individuals with PCT have
hyperpigmentation in sun-exposed areas, while one-third
of patients develop patches of alopecia as a result of
scarring from large blisters on the scalp. In most cases,
patients exhibit abnormal liver function tests. Long-term
complications include an increased risk for hepatic
cirrhosis and hepatocellular carcinoma. Iron overload may
occur in association with PCT. Hemosiderosis is usually
mild or moderate, although can be severe. Interestingly,
patients with hereditary hemochromatosis are more likely
to experience symptoms of PCT than individuals in the
general population.
PCT is observed more frequently in males than in
females. It is hypothesized that this may be related to
varying levels of alcohol consumption and other
environmental exposures between men and women. A
second theory postulates that menses may provide a level
of protection for women as it acts as a form of
phlebotomy, which is an effective treatment for PCT.
The diagnosis of PCT is easily established through
elevations of uroporphyrin and heptacarboxylporphyrin
in 24-hour urine porphyrins (#8562 Porphyrins,
Quantitative, Urine) and uroporphyrin in plasma (#8733
Porphyrins, Fractionation, Plasma). In PCT urine
uroporphyrin levels are typically elevated to at least 4
times the upper limit of normal, but concentrations may
reach as high as 250 times the upper limit of normal. In
general, heptacarboxylporphyrin is at least 25% of the
uroporphyrin value. (Elevated uroporphyrin without a
concomitant elevation of heptacarboxylporphyrin is often
observed in the acute porphyrias, rather than PCT.)
A urine uroporphyrin level twice the upper limit of
normal is suspicious for PCT and justifies further
investigation. Thus, subsequent plasma and fecal (#81652
Porphyrins, Feces) porphyrin analyses and a repeat urine
porphyrin analysis are recommended, particularly if
symptoms develop or continue to persist. Plasma testing
in cases of PCT demonstrates plasma porphyrin levels
that are typically elevated at least 5 times the upper limit
of normal. Conversely, mild elevations in plasma levels
are associated with renal disease.
Sporadic versus familial PCT can be distinguished by
enzyme analysis (#8599 Uroporphyrinogen Decarboxylase
[Upg D], Erythrocytes) and eliciting a thorough family
history. Enzymatic assay is not an appropriate first-level
assay as the majority of cases are sporadic and the enzyme
exhibits normal activity in these cases.
The cutaneous symptoms of PCT are more amenable to
treatments than are similar complications seen in other
forms of porphyria. Phlebotomy therapy and low-dose
chloroquine, an antimalarial drug, result in complete
2
11/02

Figure 1. Heme Biosynthetic Pathway
11/02 3

emission of skin lesions in most cases. Phlebotomy
produces remission by gradually reducing the hepatic
iron overload. Serial serum ferritin (#8689 Ferritin, Serum)
and plasma porphyrin (#8733 Porphyrins, Fractionation,
Plasma) levels are useful in evaluating the efficacy of
treatment. Low-dose chloroquine treatments have proven
valuable as the drug complexes with excess porphyrins,
promoting excretion. However, these therapies should
only be initiated following biochemical confirmation of
the clinical diagnosis, as they are not useful in other
porphyrias presenting with cutaneous symptoms.
Occurrences of dermatologic complications can be
minimized through elimination or reduction of
precipitating factors via sun avoidance and use of
sunscreen, abstaining from alcohol, discontinuing
estrogen therapy, or treatment of an underlying liver
disorder. Even with these treatments, long-term follow-up
is important for all patients as a means of monitoring for
relapse through urine (#8562 Porphyrins, Quantitative,
Urine) and plasma (#8733 Porphyrins, Fractionation,
Plasma) porphyrin analysis, and for the management of
any concomitant liver disease.
Generally, PCT is not attributable to a single causal factor.
Even in familial PCT, most patients have identifiable risk
factors in addition to the hereditary enzyme deficiency.
Therefore, all patients presenting with PCT should be
evaluated for multiple risk factors, including testing for
hepatitis C virus and screening for hemochromatosis, and
treated accordingly.
Hepatoerythropoietic Porphyria
Hepatoerythropoietic porphyria (HEP) is a severe
porphyria due to markedly deficient uroporphyrinogen
decarboxylase activity or homozygous PCT. Onset of
this rare porphyria usually occurs in infancy or
childhood, although cases presenting in adulthood have
been described. Patients experience severe
photosensitivity leading to blistering lesions and
scarring. Other complications include pink or red urine,
hypertrichosis, erythrodontia (reddish discoloration of
the teeth), hepatosplenomegaly, and hemolytic anemia.
Treatment is limited to sun avoidance and the use of
sunscreens.
Erythropoietic Protoporphyria
A deficiency of the enzyme ferrochelatase is observed in
patients with erythropoietic protoporphyria (EPP). EPP
is an autosomal dominant disorder with reduced
penetrance. Only about 10% of individuals with an
enzyme deficiency develop clinical symptoms. While
onset usually occurs before 10 years of age, clinical
presentation may occur during childhood or adulthood.
Individuals with EPP are sensitive to most of the visible
light spectrum. Such exposure causes burning, itching,
and painful erythema and edema that can develop
within minutes. Blistering and scarring is less common
than in other dermatologic porphyrias. Repeated
exposures may result in chronic changes giving the skin
a waxy, thickened appearance with faint linear scars.
Cutaneous photosensitivity is exacerbated in the spring
and summer when exposure to sunlight is more likely.
Patients are at an increased risk to develop hemolytic
anemia. Gallstone formation is common, and some
individuals with EPP experience mild hypertriglyceridemia.
Liver dysfunction and hepatic failure are observed in up
to 20% and less than 5% of patients, respectively.
Patients with EPP accumulate protoporphyrin in
erythrocytes, plasma, and feces. Other heme pathway
intermediates do not accumulate, and protoporphyrin is
not soluble in urine. For these reasons, urinary
porphyrin, ALA, and PBG are not useful diagnostic tools
for this disorder. When a diagnosis of EPP is suspected,
the tests of choice are total porphyrins and
protoporphyrin fractionation (#8536 Porphyrins, Total,
Erythrocytes or #8739 Protoporphyrins, Fractionation,
Erythrocytes) in erythrocytes. Unaffected individuals
have approximately 60 µg/dL total protoporphyrin with
approximately 85% being zinc-complexed and 15% or
less free protoporphyrin. In EPP patients, the total
erythrocyte protoporphyrin is significantly increased
with values usually >200 µg/dL. Some patients have
been observed with total protoporphyrin exceeding
1000 µg/dL. When the total protoporphyrin is
fractionated, EPP patients exhibit more free than zinccomplexed
protoporphyrin. However, iron deficiency,
lead intoxication, or in very rare cases variegate
porphyria should be suspected in patients who exhibit
total protoporphyrin in excess of 200 µg/dL but have
more zinc-complexed than free protoporphyrin.
Although EPP is the third most common porphyria,
treatment options are limited. Sun avoidance is essential,
and protective clothing and sunscreen are
recommended. Oral administration of beta-carotene
allows for increased tolerance to sunlight in most
patients. Although there are no other known
precipitating factors, many advocate the avoidance of
drugs and other elements that may induce crises in the
acute porphyrias. Liver transplantation is an option for
4 11/02

the minority of patients who experience hepatic failure.
However, this is not a cure as the excessive porphyrins
are produced in the erythropoietic cells.
Congenital Erythropoietic Porphyria
Congenital erythropoietic porphyria (CEP), also known
as Gunther disease, is an extremely rare and severe
porphyria. It is an autosomal recessive condition
resulting from markedly deficient uroporphyrinogen III
cosynthase activity. Although the disorder typically
manifests in early infancy, variability in the age of onset
and severity are thought to be related to the level of
residual enzyme activity. Prenatal manifestation of CEP
presents as nonimmune hydrops fetalis (abnormal
accumulation of serous fluid in fetal tissues) due to
severe hemolytic anemia, whereas only cutaneous
lesions are observed in the mildest cases manifesting in
adulthood.
Clinically, the majority of patients with CEP present in
infancy with dermatological complications including
photosensitivity, blistering, erythrodontia, and
hypertrichosis. The skin may become thickened, and
areas of hypopigmentation and hyperpigmentation are
observed. Recurrent blistering and secondary infection
may lead to significant scarring and mutilation.
Exposure to sunlight and other sources of ultraviolet
light exacerbate the severity of the cutaneous symptoms.
In fact, some patients present at birth when undergoing
phototherapy for hyperbilirubinemia. Ophthalmological
findings include keratoconjunctivitis (inflammation of
the conjunctiva and of the cornea), ulcerations, cataracts,
and corneal scarring that can lead to blindness.
Hemolytic anemia and other hematologic abnormalities
accompanied by splenomegaly are common. To
compensate for this, increased metabolic activity and
expansion of the bone marrow may lead to pathologic
fractures and vertebral compression or collapse. Many
patients develop porphyrin-rich gallstones. Pink or
reddish-brown urine is often observed as a result of the
increased excretion of urinary porphyrins. Moreover,
severely affected individuals exhibit growth and
cognitive developmental delays and a decreased
lifespan.
A combination of urine (#8562 Porphyrins, Quantitative,
Urine), erythrocyte (#8536 Porphyrins, Total, Erythrocytes
and #8735 Porphyrins, Fractionation, Erythrocytes), and
fecal (#81652 Porphyrins, Feces) porphyrin analyses can
diagnose CEP. Porphyrins in urine are predominantly
the I series isomers of uroporphyrin and
coproporphyrin. Patients with CEP show elevated
erythrocyte porphyrins consisting primarily of
uroporphyrin I. Coproporphyrin I is detected in feces.
The diagnosis of CEP should be confirmed by
erythrocyte uroporphyrinogen III cosynthase enzyme
analysis (#80288 Uroporphyrinogen III Synthase (Co-
Synthase) (Upg III S), Erythrocytes). Enzyme analysis
must be performed prior to blood transfusion to achieve
the most accurate results. Furthermore,
uroporphyrinogen III cosynthase testing is not useful
for carrier testing, as CEP heterozygotes cannot be
distinguished from unaffected individuals. Molecular
studies are currently not available on a clinical basis, but
may be obtained in a research setting.
Treatment for CEP requires protection from ultraviolet
light to reduce dermatological and ophthalmological
complications. To minimize the risk of mutilation,
secondary infections must be treated immediately.
Blood transfusions and splenectomy are beneficial in
some cases by decreasing porphyrin production and
limiting hemolytic anemia. Allogenic bone marrow
transplantation has proven curative for a handful of
patients. However, this therapy carries a considerable
risk for mortality.
Acute Porphyrias
The acute porphyrias include acute intermittent
porphyria, variegate porphyria, hereditary coproporphyria,
and 5-aminolevulinic acid dehydratase
deficiency. Episodic neurovisceral symptoms that can
be life threatening characterize the acute porphyrias.
Cutaneous features also may manifest in some patients.
Acute episodes can be precipitated by both endogenous
and exogenous factors. These factors and clinical
management are similar for all types of the acute
porphyrias and are discussed following the clinical
descriptions of each.
Acute Intermittent Porphyria
Acute intermittent porphyria (AIP), the second most
common porphyria, results from a deficiency in the
enzyme porphobilinogen deaminase (PBGD), also called
uroporphyrinogen I synthase or hydroxymethylbilane
synthase. AIP is aptly named for the intermittent
episodes in which patients experience acute neuropathic
symptoms. These acute episodes are potentially lifethreatening,
highly variable, and although usually short
in duration, may last from a few days to several months.
11/02 5

AIP rarely presents prior to puberty, with onset most
commonly between ages 20 and 40. It is characterized
by episodes of acute neuropathic symptoms. Most
patients, approximately 95%, experience severe
abdominal pain, often in conjunction with nausea,
vomiting, and constipation. Peripheral neuropathy is
common. However, given the extensive list of
differential diagnoses for patients experiencing
peripheral neuropathy, testing for AIP in the absence of
abdominal pain rarely identifies AIP patients and is not
recommended. Patients frequently display psychiatric
symptoms presenting in the form of psychotic episodes,
depression, and anxiety. Other features of an acute
attack include circulatory disturbances such as
hypertension and tachycardia. Dysuria and urinary
retention, sometimes requiring catheterization, may be
seen. Less frequently, patients may experience seizures,
respiratory paralysis, fever, and diarrhea.
Given the highly variable and nonspecific nature of the
neurovisceral symptoms observed in AIP attacks, the
condition is often overlooked in the clinical setting.
Unfortunately, appropriate laboratory investigations are
often not conducted, and many patients are misdiagnosed
or become incorrectly labeled as narcotic seeking. This
leads to a potentially life-threatening situation as
patients continue to be at risk for an acute attack.
Inheritance of AIP occurs in an autosomal dominant
manner with reduced penetrance. Approximately
10-20% of individuals with a PBGD enzyme deficiency
will become symptomatic during their lifetime,
although some recent studies have questioned this low
penetrance rate. 1,2 While the vast majority of patients
will never exhibit symptoms, the identification of
asymptomatic, affected individuals in families with
known AIP is crucial. The diagnosis of asymptomatic
patients allows for the avoidance of precipitating
factors, thereby minimizing the risk of a life-threatening
porphyric attack.
With respect to the initial diagnosis of symptomatic
patients believed to be in an acute AIP crisis, urine
porphyrins (#8562 Porphyrins, Quantitative, Urine),
ALA (#8406 Aminolevulinic Acid [ALA], Urine), and
PBG (#82068 Porphobilinogen, Quantitative, Random,
Urine) should be analyzed. Substantial financial savings
and improvement in the appropriateness of testing can
be attained by following our suggested testing strategies
for the acute porphyrias (see Table 1). 5 This will ensure
that another acute porphyria, with features similar to
AIP, is not missed. PBGD (#9625 Aminolevulinic Acid
Dehydratase [ALA-D] and Porphobilinogen Deaminase
[Pbg-D] (Uroporphyrinogen Synthase [UpgS]),
Erythrocytes) enzyme activity should be evaluated
either in conjunction with these urine analyses or
preferably in a stepwise fashion when indicated, based
upon the urine studies.
Identification of asymptomatic, affected family
members, including children, is possible and requires
either biochemical or molecular analysis. However,
molecular testing is not readily available on a clinical
basis at this time. Urinary ALA and PBG values are
method dependent and can vary by institution. Some
experts believe that these analytes will never fall within
the normal range in asymptomatic, affected individuals,
whereas others argue that these values can normalize in
such patients. With the assays available through Mayo
Medical Laboratories (MML), elevated urinary ALA and
PBG values have been observed in asymptomatic
individuals in whom AIP status was previously unknown.
Provision of clinical information and reason for referral
is important for accurate result interpretation.
Regarding the diagnosis of asymptomatic infants and
children, there is evidence that PBGD activity fluctuates
considerably during the first 9-12 months of life;
therefore, enzyme analysis should be performed after 1
year of age. In some cases, it is helpful to perform
PBGD analysis of known affected family members
when attempting to rule in/out AIP in asymptomatic
relatives. Given that up to 10% of asymptomatic
individuals with AIP will have a normal PBGD result,
the urine assays are important diagnostic tools.
Variegate Porphyria
Variegate porphyria (VP) is an autosomal dominant
acute porphyria that results from a reduction in the
activity of protoporphyrinogen oxidase activity. VP is
pan-ethnic, although high prevalence is reported in
South Africa (3/1000 individuals) and Finland. Reduced
penetrance is observed and symptoms very rarely
present before puberty. Clinical presentation of VP is
similar to other acute porphyrias, with symptoms
including abdominal pain, vomiting, neuropathies, and
psychiatric sequelae. However, cutaneous involvement
is usually more pronounced. In fact, dermatologic
manifestations in VP are very similar to those seen in
PCT and include blistering, hyperpigmentation, and
hypertrichosis of sun-exposed areas. Moreover, while
neuropathic symptoms appear only during acute crisis,
photosensitivity remains a chronic symptom.
In rare instances, homozygous VP, with marked
deficiency of protoporphyrinogen oxidase enzyme
6
11/02

activity, has been described. Patients typically present in
early childhood with photosensitivity resulting in
severe cutaneous manifestations, neurologic symptoms
including seizures, and developmental delay.
The diagnosis of VP relies upon porphyrin analysis in
urine (#8562 Porphyrins, Quantitative, Urine) and feces
(#81652 Porphyrins, Feces), as enzyme and molecular
analysis of protoporphyrinogen oxidase are not readily
available on a clinical basis. Depending upon whether
the patient is experiencing an acute crisis or is
asymptomatic, urine coproporphyrin, ALA, and PBG
values are elevated to varying degrees. Values may be
as high as 10-20 times normal during acute crises but
may be normal or only mildly elevated between attacks.
During crises, fecal porphyrin analysis shows
coproporphyrin levels are, at a minimum, double with a
coproporphyrin III to coproporphyrin I ratio in the 3-10
range (normal ratio

attacks rarely occur before puberty, and attack frequency
and severity decline after menopause. Interestingly, a
subset of female patients experience regular, cyclical,
exacerbations of disease in conjunction with menses.
A variety of drugs, including alcohol, have been
implicated in the induction of acute porphyric attacks.
There is consensus regarding the use and safety of
many common medications in patients with AIP. Other
drugs are not as well understood. Some commonly used
drugs, which have been classified as safe or unsafe for
use by patients with an acute porphyria, are listed in
Table 1. More extensive lists, including drugs whose
safety is still in question, are available elsewhere. 3
Medications previously established as safe should be
used whenever possible in patients with asymptomatic
or symptomatic AIP.
Nutritional status, in particular decreased caloric intake,
has been shown to induce the onset of an acute attack.
Intercurrent illnesses and surgery exhibit a causal
relationship, possibly due to increased energy requirements
during these times. Additionally, psychological stress
has been reported to contribute to AIP symptomology,
though the underlying mechanisms are not understood.
Precipitating factors likely act in an additive fashion,
and the trigger(s) of a particular crisis, cannot always be
ascertained.
Table 1. Medications and the acute porphyrias
Treatment for Acute Porphyrias
Hospitalization is often necessary for the treatment of
acute attacks. Crises are treated with increased
carbohydrate intake that may occur via intravenous
administration. Heme (hematin or heme arginate)
therapy allows for the excretion of ALA and PBG.
Efficacy is compromised if heme therapy is delayed, so
treatment should commence as soon as possible after
the onset of a crisis. Symptomatic treatment includes
frequent doses of analgesics to control pain, and
phenothiazines may be administered to control nausea,
vomiting, and anxiety. Given that pain tends to be
severe, narcotics are typically the analgesia of choice, as
nonnarcotic agents are usually inadequate.
Treatment for asymptomatic patients or between acute
porphyria crises largely relies upon the prevention of
potentially life-threatening episodes. At-risk individuals
should be counseled to avoid medications known to
precipitate attacks (Table 1), to avoid excessive alcohol
intake, to seek prompt treatment for other intercurrent
illnesses, and to maintain proper nutritional status,
including the avoidance of crash dieting. Patients
should be encouraged to wear a medical alert bracelet
allowing for proper management in the event that the
patient becomes temporarily incapacitated as a result of
an accident or acute crisis. Photosensitivity can be
minimized in VP and HCP patients by avoidance of sun
exposure, protective clothing, and pharmacotherapy in
the form of a beta-carotene analog, canthaxanthine.
Testing for Porphyria
By following our suggested testing strategy, the quality
of patient care and cost-effectiveness of testing can be
maximized. Depending upon the specific type of
porphyria suspected, certain tests are more informative
than other assays. In general, a 24-hour urine
porphyrins (#8562 Porphyrins, Quantitative, Urine)
analysis that includes porphobilinogen is the most
effective screening tool. However, when EPP is the
potential diagnosis, an erythrocyte porphyrin (#8536
Porphyrins, Total, Erythrocytes and #8735 Porphyrins,
Fractionation, Erythrocytes) and protoporphyrin
fractionation (#8739 Protoporphyrins, Fractionation,
Erythrocytes) are the most appropriate tests to perform.
For a listing of informative biochemical findings for
each type of porphyria, please refer to Table 2.
Testing strategies for each suspected porphyria are
outlined in Table 3, page 10. Ordering a battery of tests
does not enhance the quality of patient care. Rather, a
stepwise diagnostic approach is the most effective
means of ruling in/out a specific porphyria. In most
cases, when the result of the urine porphyrins test is
normal, subsequent testing in the form of fecal, plasma,
and erythrocyte porphyrin analyses and enzyme assay
are not recommended. As shown, the 24-hour urine
porphyrins (#8562 Porphyrins, Quantitative, Urine)
analysis is the most appropriate starting point. If a
8 11/02

Table 2. Informative Biochemical Findings in Porphyria
particular diagnosis is suspected, additional first-line
testing may be appropriate (tests listed in black in Table 3,
page 10); other analyses (listed in red) may be delayed
until initial results are available. While providing
minimal clinical value, additional testing creates
unnecessary expense to the referring laboratory or
physician, health insurance company, and patient.
For at least 1 week prior to testing for porphyria, and
under the guidance of the physician, the use of
medications should be avoided or minimized. If
clinically inadvisable, or if the patient is in a crisis, a list
of medications should accompany the specimen.
Additionally, the patient should abstain from alcohol
consumption for at least 24 hours prior to specimen
collection.
Abnormal results are reported with a detailed
interpretation including an overview of the results and
their significance, a correlation to available clinical
information provided with the specimen, differential
diagnosis, and recommendations for additional testing
when indicated and available. For consultation
regarding porphyrias, please contact a laboratory
director or genetic counselor in the Biochemical
Genetics Laboratory by calling Mayo Lab Inquiry
(1-800-533-1710).
Continues on page 10.
References
1. De Siervi A, Rossetti MV, Parera VE, Mendez M, Varela LS, del C
Batlle AM. Acute intermittent porphyria: biochemical and clinical
analysis in the Argentinean population. Clin Chim Acta 1999
Oct;288(1-2):63-71
2. Andersson C, Floderus Y, Wikberg A, Lithner F. The W198X and
R173W mutations in the porphobilinogen deaminase gene in acute
intermittent porphyria have higher clinical penetrance than R167W.
A population-based study. Scand J Clin Lab Invest 2000
Nov;60(7):643-83
3. Anderson KE, Sassa S, Bishop DF, Desnick RJ: Disorders of Heme
Biosynthesis: X-Linked Sideroblastic Anemia and the Porphyrias
(Chapter 124). In The Metabolic & Molecular Bases Of Inherited
Disease, 8th edition. Edited by CR Scriver. New York, McGraw-Hill,
2001, pp 2991-3062
4. Matter, SET and Tefferi, A. Acute Porphyria: The Cost of Suspicion.
Am J Med 1999 Dec;107:621-623
11/02 9

Continued from page 9.
Trichophyton Test Title Change
The test name for #82720
Trichophyton Mentagrophytes, IgE
has been changed to #82720
Trichophyton Rubrum, IgE to more
accurately reflect the test being
performed. This is a name change
only.
Cobalt Serum Specimen Correction
In the October 2002 issue the new test
announcement for #80084 Cobalt,
Serum contained a typographical
error in the specimen requirements.
The correct specimen volume is 1.0 mL
of serum in a Mayo metal-free,
screw-capped, polypropylene vial.
Table 3. Appropriateness of Testing for Porphyrias
Abstracts of Interest
Application of Rapid-Cycle Real-Time Polymerase Chain Reaction for the Detection of Microbial
Pathogens: The Mayo-Roche Rapid Anthrax Test
James R. Uhl, MS; Constance A. Bell, PhD; Lynne M. Sloan, MT(ASCP); Mark J. Espy, MS; Thomas F. Smith, PhD;
Jon E. Rosenblatt, MD; And Franklin R. Cockerill III, MD
Rapid-cycle real-time polymerase chain reaction has immediate and important implications for diagnostic
testing in the clinical microbiology laboratory. In our experience this novel testing method has outstanding
performance characteristics. The sensitivities for detecting microorganisms frequently exceed standard
culture-based assays, and the time required to complete the assays is considerably shorter than that required
for culture-based assays. We describe the principle of real-time polymerase chain reaction and present clinical
applications, including the detection of Bacillus anthracis, the causative agent of anthrax. This latter test is
commercially available as the result of a collaborative venture between Mayo Clinic and Roche Applied
Science, hence the designation The Mayo-Roche Rapid Anthrax Test.
Mayo Clinic Proceedings 2002;77:673-680
10 11/02

Metanephrine/Normetanephrine Test Adds
Hypertensive Reference Range
Hypertensives
70 years: 148-560 µg/24 hour
also may be asymptomatic or present with
sustained, rather than episodic, hypertension or an
incidentally discovered adrenal mass. Overall, most
Hypertensives
70 years: 246-753 µg/24 hour
and pheochromocytoma patients.
Hypertensives
18 years: 44-261 µg/24 hour
Hypertensives
70 years: 180-646 µg/24 hour
0-2 years: Not established
Hypertensives
3-8 years: 18-144 µg/24 hour
18 years: 30-180 µg/24 hour
Move to LC-MS/MS
Hypertensives
Recently, the Biochemical Genetics Laboratory
70 years: 148-560 µg/24 hour
82492
11/02 11

Meeting Calendar
Interactive Satellite Programs . . .
October 22, 2002
Bone Marker Assays: Are They Useful for the Diagnosis
& Treatment of Osteoporosis?
Presenter: Lorraine Fitzpatrick, MD
Moderator: Robert Kisabeth, MD
November 19, 2002
HIV Update
Presenter: Zelalem Temesgen, MD
Moderator: Robert Kisabeth, MD
December 10, 2002
Stroke Prevention and Management
Presenter: David Wiebers, MD
Moderator: Robert Kisabeth, MD
For a complete listing of all the courses offered throughout the year,
contact the Mayo Reference Services
Education Office at 1-800-533-1710 or 507-284-8742.
Did You Know?
Childhood porphyrias are an uncommon group
of metabolic disorders that result from inherited
deficiencies of enzymes involved in the heme
biosynthetic pathway. Although childhood
porphyrias have been reported globally, their
exact incidence is unknown. The inheritance
patterns of these disorders are complex.
Phenotypic variability is common among
individual disease states and results partly from
the presence of genetic heterogeneity. Childhood
porphyrias typically present with
photosensitivity and unique skin lesions. Therapy
is limited and consists mostly of symptomatic
and preventive measures. Although the disease
course is variable, mortality from these disorders
is rare.
For the complete article, see “Childhood
Porphyrias” by Iftikhar Ahmed MD, Mayo
Clinic Proceedings 2002;77:825-836. The
complete article also is available on-line at
www.mayo.edu/proceedings.
Communiqué
Editorial Board:
Lee Aase
Kathy Bates
Jane C. Dale, MD
Tammy Fletcher
Terry Jopke
Denise Masoner
Anita Workman
Communiqué Staff:
Managing Editor: Denise Masoner
Medical Editor: Jane C. Dale, MD
Contributors: Iftikhar Ahmed MD; Franklin Cockerill III MD; Patricia Krause;
Kara Mensink MS; April Studinski MS, CGC
The Communiqué is published by Mayo Reference Services to provide laboratorians with
information on new diagnostic tests, changes in procedures or normal values, and continuing
medical education programs and workshops.
A complimentary subscription of the Communiqué is provided to Mayo Medical Laboratories’
clients.
Stabile Building
150 Third Street SW
Rochester, Minnesota 55902-3332
MC2831/R1102
© 2002, Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. MAYO, Mayo
Reference Services and the triple-shield Mayo logo are trademarks and/or service marks of MFMER.

Q:
A:
Ask
(
US
Why do you contact the ordering physician each time the coproporphyrin isomers test
(#8652 Coproporphyrin Isomers, Series I & III, Urine) is ordered?
The test for coproporphyrin isomers (#8652 Coproporphyrin Isomers, Series I & III, Urine) is often
ordered incorrectly. This assay is primarily utilized to rule in/out the hyperbilirubinemia disorders,
Dubin-Johnson or Rotor syndromes. It is not useful in the diagnosis of porphyrias. Bilirubin is derived
exclusively from heme metabolism. In Dubin-Johnson and Rotor syndromes, conjugated bilirubin accumulates
and transport is suppressed. Hyperbilirubinemia is the key feature of both syndromes. Patients with either
disorder have normal liver function tests and histologically normal livers with the exception of gross
pigmentation of the liver associated with Dubin-Johnson syndrome.
When the coproporphyrin isomers (#8652) test is ordered, referring physicians are contacted via telephone to
confirm the diagnosis in question as a means of ensuring the appropriate assay has been ordered. In most cases,
the physician is concerned about a potential porphyria diagnosis, and the 24-hour urine porphyrins test (#8562
Porphyrins, Quantitative, Urine) is the appropriate test to order. The specimen requirements are identical,
allowing for the coproporphyrin isomers to be canceled and the 24-hour urine porphyrins assay to be ordered.
This thereby reduces expenses billed in turn to the referring laboratory or physician, health insurance company,
and patient.
As a referring laboratory, you can aid in minimizing the turnaround time and telephone calls to you and your
referring physicians’ offices by confirming the suspected diagnosis prior to ordering testing or by providing
clinical information with the specimen. If you have questions regarding this, please contact a genetic counselor in
the Biochemical Genetics Laboratory by calling Mayo Laboratory Inquiry at 1-800-533-1710.
Q:
A:
What is the most appropriate MML test to order when I want an analysis of uroporphyrins and
coproporphyrins?
In most instances, testing for uroporphyrin and coproporphyrin is requested to rule out porphyria.
Urine porphyrin analysis (#8562 Porphyrins, Quantitative, Urine) provides quantitation of
uroporphyrins, coproporphyrins, the intermediate porphyrins (pentacarboxyl, hexacarboxyl, and
heptacarboxyl), and porphobilinogen. This test is generally the first step in evaluating a patient for porphyria.
The interpretive result provided will guide the clinician in selecting additional testing as necessary.
The analysis of coproporphyrin isomers (#8652 Coproporphyrin Isomers, Series I & III, Urine) is not a useful
diagnostic tool for the porphyrias. This test should not be utilized when testing of uroporphyrins and
coproporphyrins are desired.
Continued on back
11/02 Ask Us

Continued
Q:
A:
If I suspect porphyria, what test should I order?
When a porphyria diagnosis is suspected, it is most useful to begin the patient’s workup with a single
test, the 24-hour quantitative urine porphyrin analysis (#8562 Porphyrins, Quantitative, Urine).
Frequently, multiple porphyrin tests are inappropriately ordered on a patient. However, there is no need
to begin an evaluation with this extensive level of testing. By beginning the assessment with testing for urine
porphyrins and performing further testing only when indicated based upon these results, most porphyrias (see
Q/A regarding EPP below), can be ruled out at minimal cost and inconvenience to the patient. When the urine
porphyrin analysis yields abnormal results, the interpretive result provided will guide the clinician in selecting
any appropriate additional tests.
In cases where the results of the urine porphyrin analysis are normal, and the specimen was collected while the
patient was experiencing symptoms (such as blistering or an acute crisis), further testing is generally not
warranted. However, if the specimen was collected during an asymptomatic period, repeat testing should be
considered when the patient is experiencing symptoms thought to be consistent with a porphyria.
Q:
A:
What testing should be ordered when a diagnosis of erythropoietic protoporphyria is suspected?
When erythropoietic protoporphyria (EPP) is suspected, the appropriate tests of choice are total
porphyrins and protoporphyrin fractionation (#8536 Porphyrins, Total, Erythrocytes or #8739
Protoporphyrins, Fractionation, Erythrocytes) in erythrocytes. Unlike the evaluation of other porphyrias,
analysis of urine porphyrins is not useful for this disorder because protoporphyrin is not soluble in urine and
other heme pathway intermediates do not accumulate in the urine.
Ask Us