**Core Concept**
In chronic renal failure (CRF), the kidneys lose their ability to filter waste products and maintain electrolyte balance, leading to various metabolic disturbances. One of the key consequences of CRF is the retention of phosphate, which is normally excreted by the kidneys.

**Why the Correct Answer is Right**
Hypophosphatemia is not typically seen in chronic renal failure because the kidneys are unable to effectively excrete phosphate, leading to its accumulation in the blood. In contrast, the body's ability to excrete potassium is impaired, resulting in hyperkalemia (Option A). Similarly, the kidneys' inability to acidify the urine leads to metabolic acidosis (Option B). However, CRF is often associated with secondary hyperparathyroidism, which can lead to increased phosphate reabsorption in the kidneys and hypocalcemia (Option D) due to the formation of calcium phosphate complexes.

**Why Each Wrong Option is Incorrect**
**Option A:** Hyperkalemia is a common finding in CRF due to the kidneys' impaired ability to excrete potassium.
**Option B:** Metabolic acidosis is also a common complication of CRF, resulting from the kidneys' inability to acidify the urine.
**Option D:** Hypocalcemia is often seen in CRF due to secondary hyperparathyroidism and the formation of calcium phosphate complexes.

**Clinical Pearl / High-Yield Fact**
In patients with chronic renal failure, it's essential to monitor phosphate levels closely, as hyperphosphatemia can lead to secondary hyperparathyroidism, osteodystrophy, and other complications.

✓ Correct Answer: C. Hypophosphatemia