A severe form of I-cell disease (mucolipidosis II) can present in the newborn period as multiple fractures. The bone disease in these patients is believed to be due to hyperparathyroidism. We report a case where bone disease was present at birth but the parathyroid hormone levels were initially normal and did not increase until 37 d of age. Supplemention with vitamin D was needed to normalize the parathyroid hormone levels despite adequate intake of vitamin D, calcium and phosphorus. We suggest that in patients with I-cell disease, continued evaluation for hyperparathyroidism may be necessary despite initial normal parathyroid hormone levels.
Keywords: I-cell disease; hyperparathyroidism; mucolipidosis II; rickets; vitamin D.