URINARY-EXCRETION OF EPIDERMAL GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-ALPHA IN BREAST-FED AND FORMULA-FED INFANTS

Urinary epidermal growth factor (EGF) and transforming growth factor-a lpha (TGF-alpha) concentrations were determined by radioimmunoassay in a longitudinal study analyzing 348 24-h urine specimens of 32 infants (16 breast-fed, 16 formula-fed) during the first 16 weeks of life. EG F excretion showed a statistically significant increase from 6.0 +/- 2 .5 to 14.1 +/- 4.9 mu g/g creatinine (mean +/- 1 SD) during the invest igation period. TGF-alpha levels were fairly constant throughout this period. Comparing breast-fed infants, with more than 100-fold higher i ngestion of EGF and TGF-alpha, with formula-fed infants, no significan t differences in urinary EGF and TGF-alpha excretion were observed. Th ese results do not rule out a systemic effect of EGF and TGF-alpha aft er intestinal absorption in breast-fed infants. The results suggest, h owever, that urinary EGF and TGF-alpha originate mainly from sources o ther than intestinal absorption.