How is hyperparathyroidism typically manifested in labs?

How is hyperparathyroidism typically manifested in labs?

• A. Hypercalcemia with high phosphate and elevated PTH
• B. Hypocalcemia with high phosphate
• C. Hypercalcemia with low phosphate and often elevated PTH
• D. Hypophosphatemia with low PTH

Answer: (C)

Hyperparathyroidism elevates PTH, which raises serum calcium through bone resorption, increased renal calcium reabsorption, and enhanced intestinal absorption via activated vitamin D. At the same time, PTH promotes phosphate excretion by the kidneys, leading to a low serum phosphate. So the typical lab pattern is high calcium, low phosphate, and elevated PTH. This distinguishes it from scenarios with high phosphate or low PTH, which don’t fit primary hyperparathyroidism.

Hyperparathyroidism elevates PTH, which raises serum calcium through bone resorption, increased renal calcium reabsorption, and enhanced intestinal absorption via activated vitamin D. At the same time, PTH promotes phosphate excretion by the kidneys, leading to a low serum phosphate. So the typical lab pattern is high calcium, low phosphate, and elevated PTH. This distinguishes it from scenarios with high phosphate or low PTH, which don’t fit primary hyperparathyroidism.