What is typically elevated in hyperparathyroidism?

• A. Serum phosphate
• B. Serum sodium
• C. Serum calcium (hypercalcemia) with elevated PTH
• D. Serum chloride

Answer: (C)

In primary hyperparathyroidism, the parathyroid glands overproduce parathyroid hormone, which raises serum calcium through three main actions: increasing bone resorption, increasing calcium reabsorption in the kidneys, and enhancing intestinal calcium absorption via activation of vitamin D. This leads to hypercalcemia, and the presence of elevated PTH confirms the disorder. That combination is why the best answer is a high calcium level with elevated PTH.

Other labs aren’t typically elevated in this condition. Parathyroid hormone increases renal phosphate excretion, so serum phosphate is usually low or normal rather than elevated. Sodium and chloride levels aren’t specifically driven up by PTH in hyperparathyroidism, so they’re not the hallmark findings.