Uncommon cribfellows: an infant with hypercalcemia, nephrocalcinosis, and acidosis: Questions

Excerpt

A 2-week-old girl presented with emesis and failure to thrive. She was treated with ranitidine and lansoprazole for presumed gastroesophageal reflux. Her birth weight was 3.5 kg (70th percentile). Physical exam was notable for a weight of 3.42 kg (30th percentile) but was otherwise unremarkable. Laboratory studies at 5 weeks of age revealed a serum sodium level of 136 (normal 133–140)  mmol/L, potassium level of 4.1 (normal 4.1–5.8)  mmol/L, chloride level of 105 (normal 96–106)  mmol/L, carbon dioxide concentration of 18 (normal 20–26)  mmol/L, creatinine level of 0.2 mg/dL and calcium level of 11.7 (normal 9.3–10.7) mg/dL. Over the next 2 months she had persistent emesis and poor weight gain. Serial evaluation of her electrolytes over that time perod demonstrated serum calcium and bicarbonate levels which ranged from 11.2 to 11.7 mg/dL and from 17 to 20 mmol/L, respectively. Urinalysis showed a specific gravity of 1.001, pH of 7.5 and no blood or protein. …