Sir.—I read with interest the recent article by Venkataraman et al.1 In January 1985, I encountered a similar patient who developed late-onset hypocalcemia, hyperphosphatemia, and tetany and who responded well to calcium supplementation and a change to a low-phosphate formula (Ross PM 60/40).
Patient Report.—The patient was born to a gravida 4, para 4 mother following a pregnancy complicated by gestational diabetes. Her birth weight was 4.9 kg, and length was 54.5 cm (both greater than the 95th percentile). She was fed a humanized cow milk formula (Similac with Iron) and had no documented hypoglycemia or polycythemia while she was in the nursery. On the third day of life, the patient's mother noticed one episode of rhythmic head twitching that lasted for 10 to 15 s. No other abnormal movements were noted in the nursery. On the fourth day of life, the patient's mother noticed rhythmic jerking