Physiological growth hormone secretion in adult growth hormone deficiency: comparison with normal controls

A comparison was made between the pulsatile pattern of growth hormone secretion in 14 growth hormone deficient adults (serum growth hormone less than 7 mU/I following insulin-stimulated hypoglycaemia) and 14 age and sex matched controls. The 24-h secretory profile was generated by 2-hourly sampling from 0800 to 2200 h, and 30-min sampling from 2200 to 0600 h. Plasma GH in each sample was measured using a double antibody radioimmunoassay. The profiles were analysed using a computer program (Pulsar). Sleep-electroencephalography was recorded in all subjects. The total amount of GH secreted in a 24-h period (area under the curve over baseline) was significantly less in the growth hormone deficient group (P less than 0.002). The pulse frequency, amplitude, height and percentage GH secreted in peaks were also significantly less in the growth hormone deficient group (P less than 0.002 respectively). We conclude that adults deficient in GH, as defined by conventional pharmacological stimuli, are in addition physiologically deficient of pulsatile GH secretion.