Plasma somatomedin activity in an infant with Beckwith Wiedemann syndrome.

Plasma growth hormone levels and somatomedin activity were determined in a child with Beckwith--Wiedemann syndrome at birth and at 8 mth of age. Birthweight and length were above the 97th centile. Somatomedin activity in the cord plasma was elevated (2.8 U/ml) compared with controls (0.15--1.3 U/ml; n = 15). Growth hormone was also high (76 ng/ml compared with control group range of 5.5--42.1 ng/ml, n = 26). At 8 mth of age both somatomedin activity and plasma growth hormone had fallen to normal levels and weight and length were on the 75th centile. It is suggested that the high somatomedin activity may have been a contributing factor in the excessive fetal growth of this child.