RENAL GLOMERULAR FILTRATION AND ITS RELATIONSHIP TO HYPOCALCAEMIA OF THE NEWBORN. THE EFFECT OF HYPOCALCAEMIA ON THE DEVELOPMENT OF DENTAL ENAMEL

We have shown that in almost all breast fed infants there is a rise in plasma calcium between the first and seventh day, but in artificially fed infants half show a fall in calcium over this period, resulting in 9% actually developing levels of less than 7mgs/100ml. Urinary calcium excretion of 1-2mgs/24hrs. cannot account for the fall in plasma calcium. There is an inverse relationship between plasma phosphate and urinary phosphate, suggesting that high plasma phosphate is due to impaired renal excretion. Renal clearance of phosphate was proportional to creatinine clearance. High plasma phosphate was associated with low plasma calcium. Infants that showed a fall in plasma calcium had significantly lower creatinine clearance than infants that showed a rise. Every child who had had hypocalcaemic convulsions showed very severe abnormalities of the dental enamel. 17% of infants who had had symptomatic hypocalcaemia had similar lesions. The overall incidence of severe enamel abnormalities resulting in loss of the primary dentition by the age of 3-4 years, is between 1.5 to 2% of bottle fed infants.