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/l 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 < 0.002). The pulse frequency, amplitude, height and percentage GH secreted in peaks were also significantly less in the growth hormone deficient group (P < 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.