Familial hypocalciuric hypercalciemia: clinical case report

Hypercalcemia is a laboratory-confirmed syndrome with an increase in blood calcium levels above 2.55 mmol/l. A number of authors claim that the most common causes of hypercalcemia are malignant neoplasms, primary hyperparathyroidism (PHPT), vitamin D intoxication, and chronic kidney disease. One of the rarest causes to consider in patients with newly diagnosed hypercalcemia is familial hypocalciuric hypercalcemia syndrome (FHH). FHH is a genetic autosomal dominant disorder characterized by decreased urinary calcium levels and increased blood calcium levels in combination with normal or above-reference PTH levels. The presented case demonstrates the need to perform a differential diagnosis of hypercalcemia syndrome, the importance of calculating the ratio of renal calcium clearance to creatinine clearance, which is currently the most accessible method and allows one to avoid unjustified parathyroidectomy.