GROWTH-HORMONE PULSATILITY IN ACTIVE AND CURED ACROMEGALIC SUBJECTS

GH secretion in normal subjects is periodic, with pulses prevailing du ring sleep. During the day (basal secretion), GH levels are, in genera l, undetectable. We studied GH secretion by cluster analysis, collecti ng samples every 20 min for 24 h in 44 subjects: 11 patients with acti ve acromegaly; 16 ''cured'' acromegalics, and 17 normal subjects. The purpose of this study was to compare GH secretion between patients wit h active acromegaly and ''cured'' patients and between ''cured'' acrom egalic patients and normal controls. The number of pulses detected thr ough the 24-h GH profile was not different between acromegalic patient s regardless of disease activity (17.5 +/- 4.4 vs. 15.0 +/- 6.0, respe ctively), but was different when active acromegalic patients and norma l controls were compared (8.1 +/- 1.0; P < 0.05) and when cured acrome galic patients and normal controls were compared (P < 0.05). The GH pu lsatile secretion/total GH secretion ratio was higher in normal contro ls than in acromegalic patients regardless of disease activity. We con cluded that 1) the increases in GH pulsatility in active and cured acr omegalic patients are similar, but most of the 24-h GH secretion is no npulsatile; 2) half of the GH secretion in normal subjects occurs duri ng pulses; 3) cured acromegalic patients, even those with normal GH an d insulin-like growth factor I levels, do not recover a normal GH secr etory pattern.