Study of chromatographic profiles of hGH in normal and acromegalic subjects

The chromatographic pattern of circulating growth hormone was studied by Spehadex G-100 gel-filtration in 6 acromegalic subjects and in 4 newborns. Blood was obtained by venipuncture of a forearm vein in acromegalics and from cord blood, immediately after delivery, in newborns. Serum was obtained by centrifugation after clotting at room temperature and stored frozen (-20° C) until chromatographed. GH was assayed in every fraction by radioimmunoassay. Big-big GH was in acromegalics 18.7 ± 6.7 ng/ml (M + SEM, 19.02 ± 2.90%), Big-GH was 20.4 + 12.6 ng/ml (16.53 + 6.46%) and little was 50.7 + 12.7 ng/ml (64.44 + 5.83%). In newborns the three forms were respectively 5.43 + 0.9 ng/ml (14.43 + 2.95%), 6.7 + 1.8 ng.ml (17.15 + 4.81%) and 26.82 + 3.62 ng/ml (68.5 + 3.92%). No statistically significant difference was noticed between the two groups studied. Although the monomeric form is predominant it should be noted that the macromolecular forms are quite abundant (about 30% of total circulating GH) and, therefore, must have some pathophysiological significance. The fact that newborn subjects show similar profiles, however, is in contrast with the hypothesis that the polymeric forms are due to biosynthetic alterations of the adenomatous cells. The opposite biological effect of GH hypersecretion in these two groups (high somatomedin in acromegalics, low somatomedin in newborns) therefore seems to be due mainly to a different responsiveness of the somatomedin-inducer system.