Professional and Linguistic Assessments Board (PLAB) Practice Exam

What condition is indicated by hypercalcemia with normal or raised PTH levels?

1. Secondary hyperparathyroidism

2. Primary hyperparathyroidism

3. Hypoparathyroidism

4. Primary hypercalcemia

The correct answer is: Primary hyperparathyroidism

Hypercalcemia with normal or raised parathyroid hormone (PTH) levels is indicative of primary hyperparathyroidism. In this condition, the parathyroid glands are overactive and produce excess PTH, leading to increased calcium levels in the blood. This occurs independently of the body's calcium levels; hence, even when there is hypercalcemia, the PTH levels can still be normal or elevated. Primary hyperparathyroidism typically results from a benign tumor of the parathyroid glands (adenoma) or hyperplasia of these glands. The increase in calcium can lead to various clinical manifestations, including kidney stones, bone pain, and gastrointestinal symptoms due to the high levels of serum calcium. Other conditions often associated with hypercalcemia, such as secondary hyperparathyroidism, typically present with elevated PTH levels in response to low calcium, while hypoparathyroidism results in low PTH levels with low calcium. Primary hypercalcemia could imply a different etiology, such as malignancy or vitamin D excess, where PTH would generally be suppressed. Therefore, the correlation of normal or elevated PTH levels with hypercalcemia strongly supports the diagnosis of primary hyperparathyroidism.