Differential diagnosis of hypercalcemia in a patient with CKD G5D

Patients with chronic kidney disease are characterized by the development of mineral disorders due to a decrease in the number of functioning nephrons. These changes manifest by the development of secondary hyperparathyroidism (the overproduction of intact parathyroid hormone (PTH) associated with the serum hypocalcemia, hyperphosphatemia), dysfunctional vitamin D metabolism, bone mineralization and also extraosseous calcifications. Decreased serum PTH levels associated with hypercalcemia are suspicious for adynamic bone disease, but at the same time requires an extended differential diagnostic search (e.g. metastatic processes). One of the rare causes of hypercalcemia is a defect in 24-hydroxylase (CYP24A1). We present a case of a patient on hemodialysis with atypical secondary hyperparathyroidism and an established CYP24A1 defect.