What is the most likely next test for a patient presenting with hypercalcemia and no neck mass?

• A. PTH
• B. Calcium level
• C. Vitamin D level
• D. 24-hour urine calcium

Answer: (A)

In the context of hypercalcemia, measuring the parathyroid hormone (PTH) level is essential for determining the underlying cause of the elevated calcium levels. Hypercalcemia can be related to several conditions, including primary hyperparathyroidism, malignancy, vitamin D intoxication, and other less common disorders.

If a patient presents with hypercalcemia and no neck mass, it suggests that primary hyperparathyroidism, which can be caused by a parathyroid adenoma, may be a consideration. In this scenario, measuring the serum PTH will help differentiate between primary hyperparathyroidism and other possible causes of hypercalcemia. If PTH is elevated, it indicates primary hyperparathyroidism; if PTH is suppressed, then the hypercalcemia may be due to malignancy or other causes.

Checking the calcium level again would be redundant since it has already been established that the patient is hypercalcemic. Measuring vitamin D levels could be useful in certain contexts but is not the immediate next step to evaluate the cause of hypercalcemia. A 24-hour urine calcium test is often employed to evaluate calcium excretion and help differentiate the cause of hypercalcemia, but it is typically performed after PTH levels and further initial evaluation