Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

Which electrolyte is primarily monitored in patients with renal failure?

1. Sodium

2. Potassium

3. Calcium

4. Magnesium

The correct answer is: Potassium

In patients with renal failure, potassium is primarily monitored due to the kidneys’ crucial role in maintaining potassium balance in the body. The kidneys are responsible for excreting excess potassium; when renal function declines, this excretion capability diminishes, leading to the potential for hyperkalemia (elevated potassium levels). Hyperkalemia can cause serious cardiac complications and other metabolic disturbances, making it a critical electrolyte to monitor in these patients. While sodium, calcium, and magnesium are also important electrolytes, they do not pose the same immediate risk of life-threatening complications in the context of renal failure as hyperkalemia does. Sodium levels can be affected by various factors including fluid status, but it is potassium that requires vigilant surveillance to prevent adverse effects. Thus, potassium monitoring is essential in managing the health and safety of patients with renal failure.