What is the next step after the diagnosis of hypercalcemia is established?

Updated: Apr 11, 2018
  • Author: Thomas E Green, DO, MPH, MMM, CPE, FACEP, FACOEP; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

After a diagnosis of hypercalcemia is established, the next step is to determine the cause. Initial testing is directed at malignancy, hyperparathyroidism, and hyperthyroidism, the most common causes of hypercalcemia.

  • The measurement of circulating PTH in the serum is the most direct and sensitive measure of parathyroid gland function. A reference range is 2-6 mol/L. A nonsuppressed PTH level in the presence of hypercalcemia suggests a diagnosis of primary hyperparathyroidism. If the PTH level is suppressed in the face of an elevated calcium level, hyperparathyroidism is unlikely.

  • Parathyroid hormone-related peptide (PTHrP) is thought to mediate the hypercalcemia that develops with many malignancies. Assays to measure this peptide are available. [16]

  • Measurement of calcitriol is difficult but can be accomplished. This laboratory value is useful in diagnosing hypercalcemia secondary to a granulomatous disease such as sarcoidosis. It is often elevated in primary hyperparathyroidism.

  • Other electrolytes also may be disturbed in hypercalcemia. Serum phosphate levels tend to be low or normal in primary hyperparathyroidism and hypercalcemia of malignancy. Phospate levels are elevated in hypercalcemia secondary to vitamin D–related disorders or thyrotoxicosis. Serum chloride levels usually are higher than 102 mEq/L in hyperparathyroidism and less than this value in other forms of hypercalcemia.


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