Which of the following lists accurately reflects the expected plasma/serum changes in suspected hypoparathyroidism?

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Multiple Choice

Which of the following lists accurately reflects the expected plasma/serum changes in suspected hypoparathyroidism?

Low PTH is the main factor here. In hypoparathyroidism, the lack of parathyroid hormone leads to reduced calcium in the blood and increased phosphate, because PTH normally raises calcium (by increasing bone resorption and renal reabsorption of calcium and by boosting calcitriol to increase gut Ca absorption) and it normally lowers phosphate by promoting its excretion. With PTH low, calcium falls and phosphate rises. Bone turnover also decreases without PTH, so alkaline phosphatase levels tend to be reduced. Magnesium often drops as well, since low PTH states are associated with Mg disturbances and impaired PTH secretion. Therefore, the expected plasma/serum pattern is low PTH, low calcium, high phosphate, low ALP, and low Mg. The other patterns would fit states with higher PTH and higher calcium or lower phosphate, characteristic of hyperparathyroidism or different disorders, not hypoparathyroidism.

Low PTH is the main factor here. In hypoparathyroidism, the lack of parathyroid hormone leads to reduced calcium in the blood and increased phosphate, because PTH normally raises calcium (by increasing bone resorption and renal reabsorption of calcium and by boosting calcitriol to increase gut Ca absorption) and it normally lowers phosphate by promoting its excretion. With PTH low, calcium falls and phosphate rises.

Bone turnover also decreases without PTH, so alkaline phosphatase levels tend to be reduced. Magnesium often drops as well, since low PTH states are associated with Mg disturbances and impaired PTH secretion.

Therefore, the expected plasma/serum pattern is low PTH, low calcium, high phosphate, low ALP, and low Mg. The other patterns would fit states with higher PTH and higher calcium or lower phosphate, characteristic of hyperparathyroidism or different disorders, not hypoparathyroidism.

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