Hypercalcemia worsened after vitamin D supplementation in a sarcoidosis patient: A case report.

RATIONALE: There are many causes of hypercalcemia, with hyperparathyroidism and malignancy accounting for 90% of cases. Sarcoidosis and the intake of vitamin D supplements may also cause hypercalcemia, although the occurrence rate is low if only one is involved. We herein report a sarcoidosis patient who developed hypercalcemia after taking cholecalciferol (vitamin D supplement) for a year. PATIENT CONCERN: A 62-year-old Japanese man presented with hypercalcemia and acute kidney injury along with symptoms of fatigue and appetite loss while being followed up for sarcoidosis. DIAGNOSES: We determined that a combination of cholecalciferol supplementation and sarcoidosis had led to hypercalcemia for several reasons. First, hypercalcemia had not been noted when this patient had first been admitted due to sarcoidosis-related respiratory failure several years earlier, which we presumed that was the highest sarcoidosis disease activity. Second, low serum 25-OH Vit.D3 and high 1,25-(OH)2 Vit.D3 levels were noted despite cholecalciferol supplementation for a year, suggesting that 1-α-hydroxylase overexpression caused by sarcoidosis accelerated the conversion from 25-OH Vit.D3 to 1,25-(OH)2 Vit.D3. INTERVENTIONS: Although initially resistant to preservative management, the hypercalcemia promptly improved after starting corticosteroid treatment. OUTCOMES: Hypercalcemia and acute kidney injury were normalized after corticosteroid treatment. LESSONS: We should be aware of patients' medications, especially in patients with granulomatosis disease. The concomitant measurement of 25-OH Vit.D3 and 1,25-(OH)2 Vit.D3 levels is useful for determining the cause of hypercalcemia.