The diagnostic triad for hypoparathyroidism includes which combination?

The diagnostic triad for hypoparathyroidism includes which combination?

• A. Hypercalcemia, increased PTH, decreased phosphate
• B. Hypercalcemia, decreased PTH, increased phosphate
• C. Hypocalcemia, decreased PTH, increased phosphate
• D. Hypocalcemia, increased PTH, decreased phosphate

Answer: (C)

PTH controls calcium and phosphate balance. When PTH is deficient, calcium falls because there’s less bone resorption, less calcium reabsorption in the kidney, and less activation of vitamin D to boost gut calcium absorption; at the same time, phosphate rises because there’s less PTH-driven phosphate excretion in the kidney. So the diagnostic pattern for hypoparathyroidism is low calcium, low PTH, and high phosphate. The other patterns don’t fit: high calcium suggests excess PTH activity, and a high PTH level with normal or low phosphate points away from true hypoparathyroidism.

PTH controls calcium and phosphate balance. When PTH is deficient, calcium falls because there’s less bone resorption, less calcium reabsorption in the kidney, and less activation of vitamin D to boost gut calcium absorption; at the same time, phosphate rises because there’s less PTH-driven phosphate excretion in the kidney. So the diagnostic pattern for hypoparathyroidism is low calcium, low PTH, and high phosphate. The other patterns don’t fit: high calcium suggests excess PTH activity, and a high PTH level with normal or low phosphate points away from true hypoparathyroidism.