Primary hyperparathyroidism with PTH values within the reference range: clinical case of a patient with recurrent nephrolithiasis

Hyperparathyroidism is an endocrine disease characterized by excessive secretion of parathyroid hormone (PTH) by the parathyroid glands. Primary hyperparathyroidism (PHPT) can be diagnosed biochemically with the combination of hypercalcemia and upper-normal or elevated levels of PTH. There are few descriptions of PHPT with normal intact PTH secretion in the literature. The incidence of PHPT among patients with recurrent urolithiasis is 2–8%. We present a clinical case of diagnosing PHPT in a 64-year-old female patient with rare variant of the disease. Before establishing the diagnosis, the main patient complaints were long-term recurrent nephrolithiasis and nephrocalcinosis. Surgical treatment made it possible to achieve rapid normalization of biochemical parameters of calcium-phosphorus metabolism, increase bone mineral density in the lumbar spine, improve the general condition of the patient. This clinical case demonstrates errors and late diagnosis of PHPT associated with poor knowledge of the manifestations of hyperparathyroidism and its masks. The authors recommend to determine the concentrations of total calcium, albumin, serum levels of PTH in patients with clinical picture of PHPT, in order to exclude the disease.