**Core Concept**
Renal cell carcinoma (RCC) is a type of kidney cancer that originates in the renal epithelium. Systemic abnormalities associated with RCC are a result of paraneoplastic syndromes, which are caused by substances produced by the tumor itself.

**Why the Correct Answer is Right**
The most common systemic abnormality associated with RCC is polycythemia, also known as erythrocytosis. This is due to the production of erythropoietin (EPO) by the tumor cells. EPO stimulates the production of red blood cells in the bone marrow, leading to an increase in hematocrit levels. This condition is known as secondary polycythemia or paraneoplastic erythrocytosis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Hypercalcemia is associated with several types of malignancies, including squamous cell carcinoma of the lung, but it is not the most common systemic abnormality associated with RCC.
* **Option B:** Hypocalcemia is not a common systemic abnormality associated with RCC.
* **Option C:** Hypokalemia is not typically associated with RCC.

**Clinical Pearl / High-Yield Fact**
Polycythemia is a classic paraneoplastic syndrome associated with RCC, and it is often the presenting symptom in patients with this malignancy.

**Correct Answer: C. Hypokalemia is not typically associated with RCC.