This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Medicine
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? 
Select and explain. 
A. polycythemia, B. thrombocytopenia, C. hypocalcemia, D. leukocytosis
A: polycythemia
Answer: A: polycythemia 
Explanation: 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.