Which electrolyte abnormality is commonly observed during continuous renal replacement therapy (CRRT)?

• A. Hyperkalemia
• B. Hypermagnesemia
• C. Hyponatremia
• D. Hypophosphatemia

Answer: (D)

Phosphate is continuously cleared during CRRT because the therapy removes solutes via the ongoing dialysis/replacement process. In critically ill patients, phosphate levels are already often low due to poor intake and cellular shifts, so the persistent removal with CRRT tends to push phosphate down further. This makes hypophosphatemia a common electrolyte disturbance during CRRT. Low phosphate impairs ATP production, which can weaken skeletal and diaphragmatic muscles and even affect cardiac function if severe, so monitoring and replacement are important. Clinicians typically check phosphate levels frequently and use phosphate-containing fluids or IV phosphate to maintain normal levels, adjusting the CRRT settings as needed. Other disturbances can occur depending on dialysate or replacement fluid composition, but phosphate depletion is the most commonly observed issue with CRRT.