Hypoparathyroidism causes which of the following electrolyte changes?

Hypoparathyroidism causes which of the following electrolyte changes?

• A. Increased Phosphorus and Decreased Calcium
• B. Decreased Phosphorus and Increased Calcium
• C. Increased Phosphorus and Increased Calcium
• D. Decreased Phosphorus and Decreased Calcium

Answer: (B)

Understanding how parathyroid hormone controls calcium and phosphate is key. PTH raises serum calcium by increasing bone resorption, increasing calcium reabsorption in the kidneys, and promoting activation of vitamin D to boost gut calcium absorption. It also lowers serum phosphate by increasing its renal excretion. When PTH is deficient in hypoparathyroidism, calcium falls and phosphate rises. So the expected electrolyte pattern is decreased calcium with increased phosphorus. The alternative pattern of decreased phosphorus and increased calcium would reflect excess PTH, not this condition.

Understanding how parathyroid hormone controls calcium and phosphate is key. PTH raises serum calcium by increasing bone resorption, increasing calcium reabsorption in the kidneys, and promoting activation of vitamin D to boost gut calcium absorption. It also lowers serum phosphate by increasing its renal excretion. When PTH is deficient in hypoparathyroidism, calcium falls and phosphate rises. So the expected electrolyte pattern is decreased calcium with increased phosphorus. The alternative pattern of decreased phosphorus and increased calcium would reflect excess PTH, not this condition.