Hypervitaminosis A causing hypercalcemia in cystic fibrosis. Case report and focused review

Hypercalcemia is a rare complication of hypervitaminosis A. We report a pediatric patient with cystic fibrosis (CF) and pancreatic insufficiency who was found to have hypervitaminosis A causing hypercalcemia, complicated by nephrocalcinosis and renal impairment. The patient is a 4-year-old girl with pancreatic-insufficient CF, gastroesophageal reflux, oral aversion, and failure to thrive requiring gastrostomy tube placement. She was prescribed Source CF vitamins, but rarely received the full dose, due to emesis and intolerance. She had routine annual labs that revealed hypercalcemia with elevated blood urea nitrogen and creatinine, which were not present in her previous annual labs. Upon further questioning, her mother reported that she seemed more fatigued for a few weeks, had abdominal pain, and was urinating more frequently. Upon admission to the hospital, laboratory results revealed elevated HCO3, while serum levels of potassium, phosphorus, and albumin were within normal limits. Vitamin D (25-hydroxy) level was low, and vitamin A level was elevated. Extensive metabolic and hormonal workup for the etiology of the hypercalcemia revealed evidence of chronic renal insufficiency and elevated vitamin A levels. She had a renal ultrasound that revealed bilateral nephrocalciosis. Diagnosis of chronic hypervitaminosis A complicated by hypercalcemia was made and was managed by holding vitamin A supplements, aggressive diuresis, and prednisolone. This case emphasizes the importance of regular vitamin A monitoring in patients with CF. There is a wide variability for the lowest intake required to cause toxicity, and the lower limit to cause toxicity has not been determined.