[The 519th case: recurrent nausea and vomiting, hypercalcemic crisis, and vitamin D intoxication]

A 54-year-old female patient was admitted to the hospital presenting with a 9-month history of intermittent dry mouth, nausea, and vomiting, which had worsened over the past month. The patient had self-administered excessive doses of vitamin D₃ for over a year, experiencing recurrent dry mouth, nausea, constipation, and significant weight loss during this period. Laboratory evaluation revealed a hypercalcemic crisis, suppressed parathyroid hormone (PTH) levels, a serum 25-hydroxyvitamin D [25(OH)D] concentration exceeding 600 nmol/L, and renal insufficiency. Alternative etiologies, including malignancies, granulomatous disorders, and endocrine diseases, were excluded, establishing a definitive diagnosis of vitamin D intoxication. Following admission, the patient was treated with hydration, calcitonin, and zoledronic acid. Serum calcium levels gradually normalized, gastrointestinal symptoms significantly improved, and renal function improved accordingly. The diagnosis and treatment of this case suggest that self-administration of excessive vitamin D supplementation is a common predisposing factor for vitamin D intoxication, which is clinically characterized by PTH-independent hypercalcemia as the core manifestation. Management requires the immediate discontinuation of vitamin D preparations, adequate hydration, the rational application of hypocalcemic drugs, and long-term follow-up to monitor serum calcium and 25(OH)D levels.