Decreased sweating in seven patients with Laron syndrome.

Previous studies have shown that sweat secretion was reduced in patients with GH deficiency and increased during GH treatment, indicating an influence of GH on sweat gland function. Thus, patients with GH deficiency have impaired thermoregulation. We report on sweat secretion rates (SSRs) in seven patients with Laron syndrome, measured by pilocarpine iontophoresis. The patients had significantly lower SSRs than healthy children matched for sex and pubertal stage (P < 0.00005) and moderately, but significantly, elevated sweat electrolyte concentrations (P < 0.00005 for potassium; P < 0.01 for sodium). These observations further supported the hypothesis that sweat gland function in humans is under the influence of the GH-insulin-like growth factor-I axis. It remains to be seen whether the decrease in SSR also leads to altered thermoregulation in patients with Laron syndrome.