**Core Concept**
Uremia is a clinical syndrome caused by the accumulation of waste products, primarily urea, in the blood due to renal failure. This condition affects multiple body systems and can cause a wide range of symptoms.

**Why the Correct Answer is Right**
The clinical abnormalities of uremia are multifactorial and involve the accumulation of various toxins, including urea, creatinine, and other nitrogenous waste products. These toxins can cause neuromuscular symptoms such as muscle weakness, tremors, and seizures, as well as gastrointestinal symptoms like nausea, vomiting, and diarrhea. Additionally, uremia can lead to cardiovascular complications, including hypertension and cardiac arrhythmias.

**Why Each Wrong Option is Incorrect**
**Option A:** Anemia is not a direct result of uremia, although patients with renal failure may develop anemia due to other factors like iron deficiency or erythropoietin deficiency.

**Option B:** Hypocalcemia is not a characteristic of uremia; in fact, patients with renal failure often develop hyperphosphatemia, which can lead to secondary hyperparathyroidism and subsequently cause hypercalcemia.

**Option C:** Hyperkalemia is a common electrolyte abnormality in patients with renal failure, but it is not the only clinical abnormality of uremia.

**Clinical Pearl / High-Yield Fact**
Patients with uremia often exhibit a characteristic "uremic odor" due to the accumulation of trimethylamine, a volatile compound produced by the breakdown of trimethylamine oxide in the gut.

**Correct Answer: C. Hyperkalemia.**