Incipient/normocalcemic primary hyperparathyroidism
Normocalcemic primary hyperparathyroidism is when the blood parathyroid hormone (PTH) levels are higher than normal but the blood calcium level is normal in patients who do not have secondary hyperparathyroidism. (see Secondary Hyperparathyroidism) It is thought to be a mild or early form of hyperparathyroidism. With this disease, patients can have blood calcium levels that are occassionally high. Many patients with normocalcemic primary hyperparathyroidism will go on to develop classic primary hyperparathyroidism. In one of the best studies, 41% of patients with normocalcemic PHPT developed worsening hyperparathyroidism (20% developed high blood calcium levels and the rest developed other problems associated with primary hyperparathyroidism like worsening bone strength). 82 However, not all patients will go on to develop classic primary hyperparathyroidism, and in fact some never progress at all. 83
It is unclear whether all patients with normocalcemic primary hyperparathyroidism require parathyroidectomy or if there is only a certain subgroup that benefit. However, research has shown that blood calcium and PTH levels typically become normal after successful parathyroidectomy. 83-86 It is still unclear what long term benefits parathyroidectomy has for patients with normocalcemic primary hyperparathyroidism, but studies are looking into this question.