How does insulin affect potassium and phosphorus?

How does insulin affect potassium and phosphorus?

• A. Raises potassium and phosphorus in serum
• B. Drives potassium and phosphorus into cells, causing serum depletion
• C. Has no effect
• D. Causes urinary excretion of potassium and phosphorus

Answer: (B)

Insulin prompts electrolytes to move into cells, not stay in the bloodstream. It activates the Na+/K+ ATPase, which pulls potassium from the extracellular fluid into cells, lowering serum potassium. It also promotes intracellular phosphate uptake for ATP production and glycolysis, so serum phosphorus drops as phosphate is taken up by cells. The main effect is an intracellular shift that can lead to hypokalemia and hypophosphatemia when insulin therapy or refeeding begins, rather than increasing urinary excretion of these minerals. Monitoring and adjusting electrolytes is often needed during treatment.

Insulin prompts electrolytes to move into cells, not stay in the bloodstream. It activates the Na+/K+ ATPase, which pulls potassium from the extracellular fluid into cells, lowering serum potassium. It also promotes intracellular phosphate uptake for ATP production and glycolysis, so serum phosphorus drops as phosphate is taken up by cells. The main effect is an intracellular shift that can lead to hypokalemia and hypophosphatemia when insulin therapy or refeeding begins, rather than increasing urinary excretion of these minerals. Monitoring and adjusting electrolytes is often needed during treatment.