[Blood somatomedin levels in neonates with congenital hypothyroidism and phenylketonuria].

A biological method was employed for assessing the somatomedin activity (SM)-IGF I-somatomedin C: 1) in 13 10 to 23-day old children with congenital hypothyroidism (CH) before starting substitution therapy with L-thyroxine and after one month lasting therapy. SM levels were significantly lower prior to the onset of therapy than in a control group (for p less than 0.01 on 1% level). The SM levels in treated children did not differ from controls. 2) 16 children with classic phenylketonuria (PKU) were also examined of the age of 12-23 days before starting dietary treatment with restricted phenylalanine (Phe). When compared with a control group SM levels were significantly lower in the PKU group (p = 0.01 on 5% level). When stable serum Phe concentrations had been obtained, following restricted Phe intake, SM levels no longer differed from the control. However statistical correlation of Phe and SM levels was not attained.