34 SERUM BONE GLA-PROTEIN (BGP) AT THE AGE OF TWO MONTHS IS MOCH HIGHER IN BREAST-FED INFANTS THAN IN FORMULA-FED INFANTS

Abstract

BGP, a protein produced by osteoblasts which has been shown to be a marker of bone growth, was determined by radioimmunoassay in 27 exclusively breast-fed and 6 formula-fed infants at the age of 2 months (mean 62.6 days, SD 2.4) as part of a prospective study of nutrition and growth in normal infants. Knee-heel length was measured with electronic calipers at the age of 1 and 2 months. In breast-fed infants the mean concentration was 274 ng/ml (SD 95) which is ten fold higher than values in 6-10 year old children previously published by us. In formula-fed infants the mean concentration was significantly lower (77 ng/ml, SD 46, p<0.001). There was no significant difference (p>0.05) in knee-heel length and knee-heel length velocity between the breast-fed and the formula-fed infants. The mean knee-heel length was 173 mm (SD 8 mm) and 168 mm (SD 11 mm), respectively. The growth velocity was 0.37 mm/day (SD 0.12) and 0.38 mm/day (SD 0.09), respectively. In conclusion BGP is much higher in breast-fed infants, and this cannot be explained by differences in length or length velocity. Thus BGP should be used with caution as a marker of linear growth in infants. Histomorphometrical parameters of bone formation rates are related to BGP levels in adults. It remains to be seen if bone structure in infants is related to mode of feeding.