SAT260 Asymptomatic Vitamin A Toxicity Causing Hypercalcemia

Abstract

Abstract Disclosure: N. Seshan: None. G. Goswami: None. Background: Vitamin A toxicity is an overlooked cause of hypercalcemia. Most cases of hypercalcemia are secondary to primary hyperparathyroidism or malignancy. High levels of Vitamin A are thought to have a direct effect on the bone by stimulating osteoclast resorption or inhibiting osteoblastic formation, therefore increasing the fracture risk. Clinical Case: 56 year old female with history of alcoholic cirrhosis complicated by hepatic encephalopathy, acute kidney injury and now status post liver transplant five months prior that was admitted for asymptomatic hypercalcemia. Initially, hypercalcemia was thought to be secondary to cyclosporine, so medication was discontinued. Hypercalcemia resolved after hydration however she was again readmitted for hypercalcemia found on routine labs. She did not show any other signs of excess vitamin A. Lab work showed calcium 12.5 mg/dL (8.6 - 10.2mg/dL), albumin 4g/dL (3.4 - 4.8g/dL), normal 24 hour urine calcium excretion, eGFR 33mL/min, parathyroid hormone 16.9 pg/mL (8.7-77pg/mL), normal 1,25-OH and 25-OH vitamin D, PTHrP 25pmol/L, AM Cortisol 9mcg/dL, TSH 1.7 mIU/L (0.35 - 4.7mIU/L), serum protein electrophoresis unremarkable. Her vitamin A level was elevated to 113 ug/dL (30-75mcg/dL) and was diagnosed with hypercalcemia due to elevated vitamin A levels. Treatment involved hydration and discontinuation of her multivitamin containing vitamin A. Current limited literature suggests discontinuing vitamin A supplements will normalize vitamin A levels over time. Her vitamin A levels improved over several months. Incidentally, due to complaints of back aches from prior injury, imaging showed acute compression fracture deformities of two thoracic vertebrae. Bone density scan showed normal bone density. Bone turnover markers were elevated indicative of increased bone resorption. Clinical Lesson/Conclusion: Hypervitaminosis A is a rare etiology of hypercalcemia. Vitamin A toxicity may be due to excess ingestion of preformed vitamin A through supplements and animal sources. Though not well understood, the proposed mechanism of vitamin A actions on the bone involves stimulation of bone resorption through increase in osteoclastic activity and inhibition of bone formation through osteoblastic suppression, leading to high serum calcium and increasing the risk of fractures. We present a unique case in a patient who developed hypercalcemia secondary to hypervitaminosis A. Presentation: Saturday, June 17, 2023