Incidental Normocalcemic Primary Hyperparathyroidism Presenting With Symptomatic Hypophosphatemia: A Case Report

Normocalcemic primary hyperparathyroidism (NHPT) is a newly defined variant of primary hyperparathyroidism (PHPT). It’s defined by consistently normal total and ionised calcium levels with elevated parathyroid hormone in the absence of secondary causes of hyperparathyroidism in at least three consecutive times over a period of three to six months. Consensus whether the same criteria used to recommend surgery in PHPT should be used to recommend surgery in NHPT is still lacking. Even though PHPT is known to cause hypophosphatemia, serum phosphate is not relevant when diagnosing it or NHPT. No current guideline include any phosphate cutoff level to guide management or indicate surgery in PHPT or NHPT patients. Herein, we present a rare case of incidental NHPT presenting with symptomatic hypophosphatemia and managed surgically.