USMLE 2 Question 24

A patient with long standing renal insufficiency develops mild generalised ecchymoses. Platelet dysfunction is suspected despite a normal platelet count.

Which test would be most useful in this patient?

a) bone marrow aspirate
b) Clot retraction
c) Tourniquet test
d) Bleeding time
e) Prothrombin time (PT)








ANSWER
The correct answer is D



Explanation
Renal insufficiency is associated with a bleeding tendency. Hemorrhagic manifestations are usually mild (i.e., ecchymoses or purpura) but can be severe in occasional patients who may have gastrointestinal tract or intracranial bleeding.

Modern techniques for the management of uremia have definitely reduced the incidence of severe bleeding episodes in patients with renal failure, but hemorrhages still represent a major clinical problem, particularly for patients undergoing surgery or invasive procedures.

The bleeding time is frequently abnormal in acquired platelet function abnormality such as that seen in uremia and the myeloproliferative syndromes. The bleeding time is usually abnormal in congenital defects of platelet function such as Glanzmann's thrombasthenia. The bleeding time is most helpful as an indicator of platelet abnormality, either in number or function. The bleeding time is usually normal when the platelet count is decreased but still more than 100,000/mm3 (100 × 109 /L). With platelet counts less than 100,000/mm3, there is a rough correlation between severity of thrombocytopenia and degree of bleeding time prolongation.

The bleeding time is usually abnormal in congenital defects of platelet function such as Glanzmann's thrombasthenia. The bleeding time is frequently abnormal in acquired platelet function abnormality such as that seen in uremia and the myeloproliferative syndromes.

In uremia, there frequently are demonstrable abnormalities in platelet function tests but not sufficient to entirely explain bleeding problems. In addition, up to 50% of uremic patients develop some degree of thrombocytopenia.

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