In suspected primary hyperparathyroidism, what biochemical pattern would you expect?

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Multiple Choice

In suspected primary hyperparathyroidism, what biochemical pattern would you expect?

Primary hyperparathyroidism causes too much PTH to be produced, usually by a parathyroid adenoma. PTH raises calcium by stimulating bone resorption, increasing renal calcium reabsorption, and enhancing intestinal calcium absorption via vitamin D activation. It also lowers serum phosphate by decreasing phosphate reabsorption in the kidneys. Because calcium is high, PTH should be suppressed, but in this condition it remains inappropriately normal or elevated. That combination—high calcium with low phosphate and non-suppressed PTH—is the biochemical pattern you’d expect. Alkaline phosphatase may be increased due to increased bone turnover. This picture helps distinguish it from scenarios where calcium is high with suppressed PTH or where calcium is normal or low with elevated PTH.

Primary hyperparathyroidism causes too much PTH to be produced, usually by a parathyroid adenoma. PTH raises calcium by stimulating bone resorption, increasing renal calcium reabsorption, and enhancing intestinal calcium absorption via vitamin D activation. It also lowers serum phosphate by decreasing phosphate reabsorption in the kidneys. Because calcium is high, PTH should be suppressed, but in this condition it remains inappropriately normal or elevated. That combination—high calcium with low phosphate and non-suppressed PTH—is the biochemical pattern you’d expect. Alkaline phosphatase may be increased due to increased bone turnover. This picture helps distinguish it from scenarios where calcium is high with suppressed PTH or where calcium is normal or low with elevated PTH.

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