Normocalcemic Primary Hyperparathyroidism. A Case Report and Literature Review

Abstract

Normocalcemic primary hyperparathyroidism (PHP) has been proposed to be a new phenotype of the disease. It is characterized by persistently high levels of parathyroid hormone (PTH) and normal calcium levels. Since there are no known causes of secondary hyperparathyroidism or PTH elevation, the exact biological mechanism is not known. It could be the first stage of the disease or a unique situation marked by resistance of the kidneys and bones to the effects of PTH. This is a disease that is getting more and more common. It is often found when evaluating perimenopausal women with low bone mass or when evaluating or following up on patients with osteoporosis. Normocalcemic PHP has a diverse and varied phenotype that ranges from cases with no usual PHP symptoms to cases with symptoms and specific complications. The method to diagnosing secondary hyperparathyroidism should focus on ruling out all possible causes, especially vitamin D deficiency (25-OH vitamin D levels less than 30ng/mL) and kidney function impairment (glomerular filtration rate less than 60 mL/min, as measured by CKD- EPI). Not much is known about its past in the wild. Some people get hypercalcemia, but more than 75% of them don't. There don't seem to be any ways to predict who will get hypercalcemia, so measuring total and adjusted calcium levels once a year is recommended. Even though measuring ionic calcium is a part of what it means to have Normocalcemic PHP and is recommended by some writers during follow-up, there are a number of real problems with it that should be kept in mind.