Practice questions answers platelet disorders

Practice questions answers

Platelet disorders

© Jun Wang, MD, PhD

1. E. Petechiae are usually associated with primary hemostasis defects, either vessel or platelet. Elevated FDP is usually associated with fibrinolysis following thrombosis, such as seen in disseminated intravascular coagulation. Leukocytosis is commonly associated with inflammatory neoplastic processes, either should have more relevant clinical presentations. Abnormalities of PT and PTT are usually seen in secondary hemostasis defects.

2. B. Acute onset of isolated thrombocytopenia in an otherwise healthy individual is most likely acute immune thrombocytopenic purpura. Precursor lymphoid neoplasms (Acute lymphoblastic leukemia) usually presents with increase immature lymphocytes, especially lymphoblasts in circulation. Hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome usually has progressive renal failure, hemolytic anemia and schistocytosis. Iron deficiency anemia is unlikely due to normal range hemoglobin. Thrombotic thrombocytopenic purpura has hemolytic anemia and schistocytosis.

3. A. Isolated thrombocytopenia in an otherwise healthy adult is most likely chronic immune thrombocytopenic purpura. Chronic lymphocytic leukemia has lymphocytosis. Hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome usually has progressive renal failure, hemolytic anemia and schistocytosis. Heparin induced thrombocytopenia has history of heparin usage, as well as thrombotic episodes. Myelodysplastic syndrome usually presents with peripheral cytopenia and hypercellular bone marrow with dysplastic changes.

4. B. Chronic immune thrombocytopenic purpura is associated with antibody against GPIIb/IIIa or GPIb/IX. ADAMTS-13 difficiency is associated with thrombotic thrombocytopenic purpura. Endothelial injury associated with thrombocytopenia can be seen in hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome or disseminated intravascular coagulation. Ineffective hematopoiesis is associated with myelodysplastic syndrome. Vitamin K deficiency, including warfarin associated coagulopathy is associated with coagulation factor deficiency and usually presents with prolong PT and PTT.

5. B. This is most likely heparin induced thrombocytopenia based on history of heparin usage, as well as thrombotic episodes. Timing of symptoms after heparin administration is another key. Liver disease associated coagulopathy is associated with coagulation factor deficiency and usually presents with prolong PT and PTT. Pneumonia or other infections are usually associated with neutrophilia. Diabetic ketoacidosis has abnormal blood glucose and electrolytes. Metastatis or recurrence of prostate cancer usually has elevated PSA.

6. D. This is most likely thrombosis caused liver ischemia. Alcoholic liver damages are chronic conditions. In addition, in alcoholic liver disease, the AST elevation is usually less than eight times the upper limit of normal, and the ALT elevation is typically less than five times the upper limit of normal. Bacterial toxin caused hepatocytic injury is unlikely due to lack of evidence for bacterial infections, such as neutrophilia. Diabetic vascular damage is also a chronic process. Metastatis or recurrence of prostate cancer usually has elevated PSA.

7. D. This is most likely heparin induced thrombocytopenia based on history of heparin usage, as well as thrombotic episodes. Timing of symptoms after heparin administration is another key.  Acute immune thrombocytopenic purpura has acute onset of isolated thrombocytopenia in an otherwise healthy individual. Pneumonia or other infections are usually associated with neutrophilia. Hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome usually has progressive renal failure, hemolytic anemia and schistocytosis. Thrombotic thrombocytopenic purpura has hemolytic anemia and schistocytosis.

8. E. Once heparin induced thrombocytopenia is suspected, all heparin products should be stopped immediately.

9. A. This is most likely thrombotic thrombocytopenic purpura due to ADAMTS-13 deficiency. Autoantibody against platelet glycoprotein IIb/IIIa is seen in chronic immune thrombocytopenic purpura. Bacterial toxin caused endothelial injury is seen in hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome or disseminated intravascular coagulation. Domestic abuse usually does not cause hemolytic anemia, and will need more evidence to support. Spectrin mutation is seen in hereditary spherocytosis. Direct Coombs tests are used to detect antibodies against host red blood cells, as seen in autoimmune hemolytic anemia.

10. A. ADAMTS-13 deficiency is seen in thrombotic thrombocytopenic purpura. Autoantibody against platelet glycoprotein IIb/IIIa is seen in chronic immune thrombocytopenic purpura. Bacterial toxin caused endothelial injury is seen in hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome or disseminated intravascular coagulation, both have either history and laboratory tests results of infection. Abnormal levels of alternative complement pathway factors are associated with atypical hemolytic-uremic syndrome. Radiologic workup of old fractures may be helpful for a domestic abuse, which has no evidence in the current case.

11. B. ADAMTS-13 deficiency can be caused by genetic abnormalities of the gene, in cases clinical presentation usually starts at younger ages, or due to autoimmune process, as seen in this case, when the patient has autoimmune disorder of SLE.

12. E. Although with many overlapping in clinical presentations and laboratory test results, thrombotic thrombocytopenic purpura usually has an ADAMTS-13 activity less than 10%, while hemolytic-uremic syndrome or atypical hemolytic-uremic syndrome usually has an ADAMTS-13 activity greater than 10%. Acute immune thrombocytopenic purpura has acute onset of isolated thrombocytopenia in an otherwise healthy individual. Myelodysplastic syndrome usually presents with peripheral cytopenia, and hypercellular bone marrow with dysplastic changes, but less likely with hemolytic anemia with schistocytosis.

13. D. Platelet transfusion is contraindicated in thrombotic thrombocytopenic purpura. Other options are all acceptable approaches to TTP management.

14. E. With the history of bloody diarrhea and acute renal failure, this is most compatible with hemolytic-uremic syndrome. Platelet activation due to antibodies against heparin-PF4 complex is seen in heparin induced thrombocytopenia. Platelet aggregates caused by ultra large von Willebrand factor multimers are seen in thrombotic thrombocytopenic purpura. Platelet destruction due to antibodies against GPIIb/IIIa is seen in chronic immune thrombocytopenic purpura. Medication caused megakaryocytic suppression usually has history of medication usage.

15. E.  Positive stool culture for shiga-like toxin producing bacteria can be seen in hemolytic-uremic syndrome. Myelodysplastic syndrome usually presents with peripheral cytopenia, and hypercellular bone marrow with dysplastic changes, but less likely with hemolytic anemia with schistocytosis. ADAMTS-13 deficiency is seen in thrombotic thrombocytopenic purpura. Presence of antibodies against heparin-PF4 complex is seen in heparin induced thrombocytopenia. Precursor lymphoid neoplasms (Acute lymphoblastic leukemia) usually presents with increase immature lymphocytes, especially lymphoblasts in circulation.

16. C. See discussions for questions 14 and 15.

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