A 69-year-old woman presents to the emergency department with symptoms of left flank pain and hematuria. On physical examination, the blood pressure is 165/96 mmHg, heart rate is 104/min, and the abdomen is soft and nontender. There is some left costo-vertebral angle tenderness on percussion. A computerized tomography (CT) scan of the abdomen reveals a 5-cm mass in the left kidney. (See Figure below) Which of the following laboratory abnormalities might also be present?: (A) polycythemia, (B) thrombocytopenia, (C) hypocalcemia, (D) leukocytosis
Answer is A. This patient likely has renal cell carcinoma (RCC). Polycythemia is caused by the production of erythropoietin-like factors. There is no relationship to hypertension. The tumor frequently presents as metastatic disease. Thrombocytopenia is not a feature of RCC, and hypercalcemia may occur if there is bone metastasis. High renin production does not occur in RCC either.