Further evaluation of the patient reveals microscopic hematuria. Laboratory results are as follows: Which of the following is the most likely cause of this patient's hematologic findings?

Question

Further evaluation of the patient reveals microscopic hematuria.  Laboratory results are as follows:  Which of the following is the most likely cause of this patient's hematologic findings?

Quizplus · Accepted Answer

This patient most likely has renal cell carcinoma with an elevated hemoglobin level suggestive of erythrocytosis. Renal cell carcinoma causes a variety of paraneoplastic syndromes. Erythrocytosis is an uncommon but classic finding and is the result of excessive erythropoietin production by the renal cell tumor. Hypercalcemia may also occur due to overproduction of parathyroid hormone-related peptide or from lytic bone metastases. (Choice A) Arteriovenous malformations have been associated with high-output cardiac failure, local bony hypertrophy, and local tissue compression and distortion. These lesions are typically congenital although they may not become clinically evident until puberty. (Choice C) When intramedullary hematopoiesis is insufficient, blood cell formation can sometimes occur in extramedullary sites such as the liver, spleen, and thymus, resulting in enlargement of these organs. Extramedullary hematopoiesis typically occurs in the setting of myelofibrosis. (Choice D) Myeloproliferative disorders such as polycythemia vera typically cause increases in all cell lines (leukocytosis and thrombocytosis would also be expected). (Choice E) Reduced plasma volume can cause a pseudo-elevation in hemoglobin/hematocrit levels. However, hemoconcentration typically causes this pseudo-elevation in all cell lines. In addition, there is no other indication of a reduced plasma volume, and in this clinical setting, erythropoietin overproduction from a renal tumor is more likely. Educational objective: Renal cell carcinoma causes a variety of paraneoplastic syndromes including erythrocytosis (due to excessive erythropoietin production) and hypercalcemia (due to parathyroid hormone-related peptide).

Further Evaluation of the Patient Reveals Microscopic Hematuria