Unexpected severe hypercalcemia in a 6-year-old child with hypoparathyroidism and feeding difficulties

Treatment of hypoparathyroidism with activated vitamin D and calcium carbonate is associated with increased risk of hypercalcemia, hypercalciuria, and nephrocalcinosis. These complications are usually due to inadvertent overdose of medications. We present a case of a 6-year-old boy with hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome and feeding difficulties who developed severe hypercalcemia twice, which was caused not just by medication. Both episodes of calcium overload were related to excessive dietary calcium intake from enteral formula. After rehydration and diet change, his blood calcium and urine calcium/creatinine ratio normalized and remained normal with the same dose of calcitriol without calcium carbonate during the following 2 years. This case underscores the importance of assessment of dietary calcium intake in children with hypoparathyroidism, especially those receiving enteral formula. It shows that calcium intake from enteral formula may even become excessive when the volume of formula is increased in pursuit of more calories, and long-term treatment of hypoparathyroidism could be successful with calcitriol without calcium supplement if dietary calcium intake is sufficient. Use of blenderized tube feeding instead of commercial enteral formula in a child with hypoparathyroidism makes it possible to increase calorie intake without causing dietary calcium excess.