GROWTH HORMONE DEFICIENCY AND THE MEASUREMENT OF SOMATOMEDIN C/IGF‐I: THE INFLUENCE OF SEXUAL MATURATION

Fifty‐nine short children 2–19 years, 25 females and 34 males, were studied for clinical and biochemical evidence of growth hormone deficiency (GHD). Group 1 (= 32), mean height SDS — 3.26 ± 1.5, mean retardation of bone age 2 years, had a mean peak GH of 6.1 ± 3.7 mIU/l during tests of GH release, and were classified as GHD. Group 2 (= 27), had a mean height SDS of ‐ 2.65 ± 1, mean bone age retardation of 1.7 years and had a mean peak GH during provocation tests of 24.3 ± 11.1 mIU/l and were classified as non‐GHD. Basal IGF‐I concentrations were correlated with height and bone age, for both groups and for GHD children, with pubertal score. Neither peak GH values nor integrated GH concentrations in a provocative test were correlated with IGF‐I values. The minimum IGF‐I concentrations occurred at a bone age of 8 years, the reference point that was taken as the average expected time of maturational change. IGF‐I concentrations rose in five GHD children when their bone age exceeded 8 years and when their free testosterone was greater than 10 pmol/l. Eighty‐nine per cent of the GHD children with a bone age at or below 8 years were identified as GHD from their basal IGF‐I values, but for, all bone ages this fell to 62.5%. Basal IGF‐I values appear to be less discriminatory for identification of GHD as sexual maturity and bone age advance.

Duke Scholars

Author John Wiley Williams Jr. Medicine, General Internal Medicine