NMS Q&A Family Medicine

322 NMS Q&A Family Medicineadenine is substituted for guanine at position 20210. Theresult is excessive levels of prothrombin and hypercoagulability,the second most common cause of otherwiseunexplained venous thrombosis.12. The answer is D. Antithrombin III deficiency isassociated with a relative resistance to heparin becauseheparin is a cofactor in the physiologic function of antithrombinIII. Thus, heparin needs antithrombin III presencefor its effectiveness. In cases in which heparinresistance is encountered, fresh-frozen plasma should begiven along with heparin.13. The answer is D. Folic acid deficiency explains a macrocyticanemia in an alcoholic who displays no signs ofposterior column abnormalities or peripheral neuropathy.Alcoholism is nearly certain, given the macrocyticanemia, lower than expected BUN and creatinine levels(insufficient protein intake), mild hepatocellular enzymeelevations with alanine aminotransferase more strikinglyso, and the physical stigmata of telangiectasias. (These arethe form fruste of spider angiomata.) The discussion ofQuestion 7 covers most of the reasoning for this unit.Pernicious anemia manifests a macrocytosis but witheventual neurologic involvement. Iron deficiency shows amicrocytosis and hypochromia; hemolytic anemias manifestincrease in urine urobilinogen and elevated unconjugatedserum bilirubin levels; beta-thalassemia is ahemolytic anemia that happens to manifest microcytosisand normochromia. Both beta- and alpha-thalassemiastend to occur in Mediterranean ethnic groups. The presentationof the patient as being of Greek descent was ared herring.14. The answer is E. Infarctions that are due to polycythemiccrises do not occur as sequelae of SCD. On thecontrary, SCD is, of course, a condition of anemia, notpolycythemia. The African-American infant with SCD istypically well until 6 to 8 months of age while his predominantlyfetal hemoglobin is gradually replaced byhemoglobin S (SS), in a homozygous sickle cell sufferer.After that age, he may begin suffering from bouts of severepain caused by splenic red cell sequestration, and he manifestssplenomegaly. In addition, the patient often suffersfrom dactylitis. By the time the infant reaches the age of 2,the spleen has infarcted to the point of atrophy and functionalasplenia. Most of the critical events attendant toSCD are directly or indirectly related to sludging of redcells and concomitant vaso-occlusive phenomena. Microinfarctionsof various tissues, such as mesentery and bone,are results of sludging. Bone infarctions cause asepticnecrosis of the humerus and femoral heads. There is alsoan acute chest syndrome that carries a 10% mortality rateand is thought to be based on microvascular pulmonaryinfarctions, occasionally leading to pulmonary embolism.Unrelated directly to vaso-occlusive disease is the hemolyticcrisis that may occur in SCD and, if not recognized,may lead to acute heart failure within a few hours.15. The answer is A. Polycythemia vera involves increasedlevels of all the formed blood elements. The only otherproblem choice that fits that picture would be Choice D,spurious polycythemia caused by dehydration and hemoconcentration.The latter is ruled out by the relativelydilute urine. Secondary polycythemia caused by altitude,chronic lung disease, or smoking should involve only theerythroid elements. Polycythemia vera is a myeloproliferativedisorder that is characterized by hypervolemia(hence hypertension), plethora, splenomegaly, and generalizedpruritus. There is a significant chance of evolutioninto myeloid leukemia. Thrombotic disease is a frequentcomplication caused by the increased viscosity of theblood. Treatment historically has been phlebotomy, andthis is still used. Also in the past, more definitive therapyincluded (radioactive) 32 P. Presently, hydroxyurea oranagrelide is used for myelosuppression. Low-dose aspirinis employed for prevention of thromboses.16. The answer is C. Multiple myeloma. The most commonpresentations are complaint of bone pain, pathologicfractures, pallor, and symptoms of fatigue; and laboratoryfindings of normocytic, normochromic anemia andhypercalcemia. Metastatic carcinoma to bone usually ischaracterized by elevated alkaline phosphatase. Multiplemyeloma features lytic but not blastic bone lesions; hence,alkaline phosphatase is not elevated, and such pathologicfractures will not show on radionuclide bone scan. Plainx-rays may demonstrate the typical lytic “punched out”metastatic lesions. Although proteinuria is not alwayspresent, as multiple myeloma proteins are light chain andnot often found in the urine, proteinuria may be presentearly. Waldenström macroglobulinemia does not involvethe bones and features heavy chain (hence the term macroglobulin) paraprotein. Although osteoporosis results inpathologic fractures, it would not explain the other findingsin the vignette. (Occasionally, osteoporosis may bethe sole skeletal finding in multiple myeloma.) Serumprotein electrophoresis readily demonstrates the monoclonalspikes. These occur in the beta- or (gamma)-globulin region in multiple myeloma, with 60% beingimmunoglobulin (Ig)G, 25% IgA paraprotein, and 15%light chain only. The spike occurs in the IgM region inWaldenström macroglobulinemia. The latter, because ofthe large chain protein, is characterized especially byhyperviscosity and problems attendant thereto. Bonemarrow examination shows infiltration by plasma cells inmultiple myeloma, comprising 5% to 100% of the content;in Waldenström macroglobulinemia, abnormalappearingplasmacytic lymphocytes are seen in themarrow and in small numbers in the peripheral smear,