A 40-year-old man with end-stage renal disease due to type 1 diabetes mellitus is hospitalized for initiation of hemodialysis. A tunneled dialysis catheter is inserted into the right internal jugular vein. Before he is able to undergo dialysis treatment, the patient develops bleeding around the catheter exit site that is difficult to control. He has not been treated recently with anticoagulants. Further evaluation of this patient would most likely show which of the following laboratory abnormalities?

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11ec160b_3973_e2c8_9249_6f955a35d028_MD0001_00 Excessive bleeding is common in patients with significant renal dysfunction due in part to the accumulation of uremic toxins in the circulation. These toxins impair platelet aggregation and adhesion, resulting in a qualitative platelet disorder characterized by prolonged bleeding time with normal platelet count, prothrombin time (PT), and activated partial thromboplastin time (aPTT). Uremic bleeding can be improved with dialysis as it removes the toxins and partially reverses the bleeding abnormality. (Choice B) von Willebrand factor (vWF) acts as a bridge between glycoprotein 1b receptors and subendothelial collagen, allowing platelets to bind to damaged vessels. vWF deficiency results in platelet dysfunction with a prolonged bleeding time and normal platelet count. Since vWF also protects factor VIII from degradation, vWF deficiency can result in decreased factor VIII and prolonged aPTT. (Choice C) Isolated aPTT prolongation is seen with hemophilia A, an X-linked disorder caused by factor VIII deficiency. Heparin use also prolongs the aPTT via antithrombin-associated inhibition of factors II and X (PT is usually normal due to the addition of heparin neutralizers in the PT reagent). (Choice D) Disseminated intravascular coagulation is a consumptive coagulopathy associated with decreased platelet count and increased bleeding time, aPTT, and PT. (Choice E) Warfarin inhibits vitamin K-dependent clotting factors (II, VII, IX, and X). Warfarin prolongs both PT and aPTT, but PT is increased much more than aPTT. Platelet count and bleeding time are normal. Education objective: Abnormal bleeding in patients with uremia is due to a qualitative platelet disorder that causes prolonged bleeding time with normal platelet count, prothrombin time, and activated partial thromboplastin time. __________ References: Coagulation assays and anticoagulant monitoring. (http://www.ncbi.nlm.nih.gov/pubmed/23233620)

A 40-Year-Old Man with End-Stage Renal Disease Due to Type