A 58-year-old man is evaluated for excessive bruising. He has a long history of type 2 diabetes mellitus complicated by nephropathy, hypercholesterolemia, and hypertension. An arterio-venous fistula was placed 2 months ago for a possible dialysis. He does not take any antiplatelet agents or anticoagulants. Blood pressure is 140/86 mm Hg. Examination shows nonpalpable purpura. Laboratory studies are as follows:
| Hemoglobin | 10.5 g/dL |
| Platelets | 138,000/mm3 |
| Blood glucose | 178 mg/dL |
| Blood urea nitrogen | 56 mg/dL |
| Creatinine | 5.5 mg/dL |
Prothrombin and active partial thromboplastin time are unremarkable. Baseline creatinine level is between 5.2-5.5 mg/dL. Which of the following is the most likely cause of this patient's abnormal bruising?
Show Explanatory Sources
This patient has chronic kidney disease (CKD) with excessive bruising and normal coagulation studies. These findings are characteristic of platelet dysfunction, a common cause of easy bruising, nonpalpable purpura, and mucosal bleeding in patients with CKD. Platelet counts are typically normal but may be mildly depressed, as seen here.
Pathophysiology of platelet dysfunction in uremia involves abnormalities in primary hemostasis. Patients with CKD have elevated urea, the end product of ammonia breakdown and immediately derived from arginine. As urea levels rise, arginine and its precursors are shunted to a different pathway that leads to nitric oxide production. Inappropriately high nitric oxide levels in CKD inhibit primary hemostasis via decreased platelet adhesion, activation, and aggregation.
Anemia in CKD (due to reduced erythropoietin production) can also contribute to platelet dysfunction by reducing platelet marginalization along the endothelial surface, further impairing platelet adherence.
(Choice A) Bleeding complications occur in acute disseminated intravascular coagulation (DIC), a consumptive coagulopathy. However, most patients have an acute risk factor (eg, sepsis, trauma), and PT and PTT are prolonged. In chronic DIC, coagulation studies may be normal, but these patients typically have thrombosis and a history of malignancy.
(Choice B) Easy bruising is typical of factor VIII deficiency (hemophilia A), but PTT would be prolonged. In addition, symptoms usually develop in early childhood.
(Choice C) Platelet destruction (eg, immune thrombocytopenia) often presents with bleeding involving the skin or mucous membranes. However, platelet counts are usually <100,000/mm3, and bleeding typically occurs only when the counts drop to <20,000/mm3.
(Choice E) Vasculitis can cause purpura; however, these are typically palpable due to inflammatory vessel injury. Nonpalpable purpura, as seen here, is typically caused by platelet or coagulation disorders.
Educational objective:
In patients with chronic kidney disease, platelet dysfunction is the most common cause of abnormal hemostasis (eg, easy bruising, nonpalpable purpura). PT and PTT are normal; platelet count is normal or mildly low.