Calcium Metabolism in Idiopathic Hypercalcemia of Infancy with Failure to Thrive

A number of cases of infants failing to thrive, apparently because of hypercalcemia, have been reported. In addition to failure to thrive, the manifestations include constipation, hypotonia, polyuria, loss of appetite, occasional vomiting and intermittent urinary infection. The syndrome occurs in mild and in severe forms. It has recently been suggested that the hypercalcemia is due either to an excessive intake of vitamin D or of calcium or may represent an unusual hypersensitivity to the action of vitamin D. The present report describes metabolic studies on a 9-month-old infant with the milder form of the hypercalcemic syndrome. Administration of 10,000 units daily of vitamin D for 10 days caused an exacerbation of the disease. On a calcium-free diet, the level of calcium in the blood returned to normal and the patient improved clinically. On a diet containing 610 milligrams of calcium per day, the calcium level in the plasma rose rapidly to abnormal levels and the symptoms recurred. The metabolic alterations closely simulated an intoxication with vitamin D. Apparently patients with this disease are abnormally sensitive to the vitamin, as most of them develop symptoms without evidence of having received more than moderate doses. The patient described eventually made a spontaneous recovery and was able to tolerate a diet of normal calcium content. The literature on the subject is reviewed and the theoretical implications are discussed. The findings are of importance for the practical management of patients with this type of disorder.