Somatomedin and growth retardation in children with chronic renal insufficiency.

The somatomedins are a family of growth hormone-dependent insulin-like peptides which have been postulated to mediate the actions of pituitary growth hormone on skeletal tissue. The somatomedin peptides are part of a larger family of growth factors. Somatomedin has been measured by bioassays, by radioreceptor assays, and recently by a radioimmunoassay. Bioassays are influenced by glucocorticoids, sulfate, heparin, and other inhibitors; radioreceptor assays from different laboratories presently give conflicting results but early experience with the immunoassay is promising. Somatomedin levels are low in hypopituitary states, in malnutrition, and in general when growth hormone is low. Somatomedin's levels in uremia are variously reported. Most bioassays report low values, although the hole of inhibitors is not clear. Values by radioreceptor assays are normal or elevated, but their specificity is unproven. No data are available using radioimmunoassay. No study has addressed end-organ responsivity in uremia.