ROLE OF PLASMA PHOSPHATE MEASUREMENTS IN DETECTING RICKETS OF PREMATURITY AND IN MONITORING TREATMENT

Twice weekly plasma and urine measurements were made in 24 very low bi rth weight infants. Intravenous feeding was given whilst infants requi red respiratory support. Subsequently they received breast milk or for mula milk with a vitamin D supplement of 400 U/day. Fourteen babies re quired intravenous feeding for more than 10 days. Six developed radiol ogical rickets or severe osteoporosis, and these infants had plasma ph osphate levels < 1.2 mmol/L on breast milk or < 1.8 mmol/L on formula milk. Babies without radiological rickets had plasma phosphate levels > 1.2 mmol/L on breast milk and > 1.8 mmol/L in all but one on formula milk. Successful treatment of rickets was associated with a rise in p lasma phosphate to the above levels. Untimed urine calcium and phospha te concentrations expressed as creatinine ratios were not helpful in d etecting babies with rickets, but may be useful in monitoring therapy.