SUN-782 A Case Of Hypercalcemia Secondary To Granulomatous Disease With Normal 1,25-dihydroxyvitamin D Levels

Abstract Disclosure: A.S. Lin: None. M. Sanchez Valenzuela: None. L. Esper: None. Introduction: Hypercalcemia secondary to granulomatous disease is typically related to high serum 1,25-dihydroxyvitamin D levels. Here, we present a case of a patient with hypercalcemia with normal serum 1,25(OH)D levels.Clinical Case: A 64-year-old female was referred from the endocrinology clinic to UVA Hospital for recurrent hypercalcemia and AKI on CKD. She had a previous hospital admission a month earlier for hypercalcemia with a calcium level of 14 (8.5-10.5) mg/dL, seen on routine labs ordered by her primary care doctor. Her calcium level improved to 10.6 mg/dL after administration of saline and calcitonin, and workup showed a low normal PTH of 21 (9.0-77.0) pg/mL, negative PTHrP of 0.9 (≤4.2) pmol/L, normal 1,25(OH)D of 44 (18-78) pg/mL; normal 25(OH)D of 42 (20-80) ng/mL, normal urine protein electrophoresis, and elevated serum free light chains in the setting of AKI. At her follow-up visits with endocrinology and nephrology, her laboratory workup demonstrated hypercalcemia of 12.2 mg/dL with a normal 24-hour urinary calcium of 117 (100-300) mg/day and a creatinine level of 3.2 (0.6-1.1) mg/dL. Calcium levels improved to 10.7 mg/dL after administering intravenous fluids. She had an additional workup, including CT abdomen and pelvis, which ruled out primary malignancy; parathyroid sestamibi scan, which was negative for parathyroid adenoma; and colonoscopy, which ruled out colon cancer. She was seen by nephrology due to persistently elevated creatinine and underwent a kidney biopsy that showed chronic active tubulointerstitial nephritis with focal non-necrotizing granuloma formation consistent with renal sarcoidosis. Her AKI and hypercalcemia resolved after treatment with a prednisone taper.Clinical Lessons: Granulomatous diseases, such as sarcoidosis, should be suspected as a cause of unexplained hypercalcemia even when 1,25(OH)D levels appear normal. In this case, hypercalcemia was not due to excess PTH and PTHrP. While sarcoidosis-related hypercalcemia is generally attributed to increased extrarenal macrophage 1,25(OH)D synthesis, disease-related dysregulation may result in inappropriately normal levels—referred to as the “inadequate normal” phenomenon.1 Regardless of measured 1,25(OH)₂D levels, corticosteroids remain the treatment of choice to address the underlying dysregulation of calcium metabolism.References:1. Gwadera Ł, Białas AJ, Iwański MA, Górski P, Piotrowski WJ. Sarcoidosis and calcium homeostasis disturbances-Do we know where we stand?. Chron Respir Dis. 2019;16:1479973119878713. doi:10.1177/1479973119878713 Presentation: Sunday, July 13, 2025