Growth in growth hormone insensitivity.

Primary GH insensitivity due to GH receptor deficiency (GHRD) provides a model for studying the discrete effects of severe IGF-I deficiency on growth and body composition. Growth failure in utero is doubtful, but postpartum growth proceeds at rates that result in adult statures 4-12 standard deviations (SDs) below the normal mean. Wide variability in statural effect, even in a genetically homogeneous population, is partly explained by correlation of SD score with biochemical measures of GH effect (IGF-I, IGF-II, and IGFBP-3). Growth and changes in body composition (decreased fat/lean) in patients with GHRD in response to exogenous IGF-I indicate that direct local effects of GH are not necessary for these responses.