**Question:** 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 non-tender. 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. Increased serum creatinine
B. Increased serum urea
C. Increased erythrocyte sedimentation rate (ESR)
D. Decreased serum albumin

**Correct Answer:** C. Increased erythrocyte sedimentation rate (ESR)

**Core Concept:**

The question is about a patient with a left kidney mass presenting with flank pain, hematuria, elevated blood pressure, and heart rate. The patient's symptoms and examination findings are suggestive of a renal pathology, most likely renal cell carcinoma. The renal mass can lead to increased blood flow to the affected kidney, resulting in hypertension and tachycardia. The patient's left costo-vertebral angle tenderness on percussion indicates possible involvement of the renal capsule or adjacent structures.

**Why the Correct Answer is Right:**

The correct answer is increased erythrocyte sedimentation rate (ESR), also known as the Westergren ESR test. The ESR is an indirect measure of inflammation, as it increases with inflammation, infection, or malignancy. Inflammation, which is commonly seen in renal cell carcinoma, can lead to increased ESR levels.

**Why Other Options are Incorrect:**

A. Increased serum creatinine and urea (option A and B) are laboratory markers of kidney function, not inflammation. Increased creatinine indicates impaired renal function, while elevated urea levels suggest impaired liver function or protein loss. Neither of these markers is directly related to inflammation or malignancy.

D. Decreased serum albumin (option D) can occur in acute inflammation, malnutrition, or liver disease, but in this scenario, it is less likely as the patient has no clinical signs of malnutrition or liver disease.

In conclusion, the correct answer (C) is chosen due to the patient's clinical presentation and renal pathology. The other options (A, B, and D) are incorrect because they relate to different aspects (renal function, liver function, and nutritional status) that are not directly related to the patient's clinical scenario involving an inflammatory process and renal mass.