Relationship between growth hormone and somatomedin-C levels in untreated acromegaly, after surgery and radiotherapy and during medical therapy with sandostatin (SMS 201-995).

Several conflicting reports have been published with regard to the relationships between circulating growth hormone (GH), Somatomedin-C (SM-C) levels and clinical activity during different stages of therapy of acromegaly. We did not find a significant correlation between (fasting, post-prandial and mean 24-h) plasma GH and SM-C concentrations in twenty-two untreated acromegalic patients. There was a statistical significant correlation, however, if only the GH levels below 100 micrograms 1(-1) were considered (n = 18 patients, P less than 0.01). The distribution of molecular forms of GH ('little', 'big' and 'big-big') did not differ between the four patients with GH levels above 100 micrograms 1(-1) and in four patients with levels between 40 micrograms 1(-1) and 80 micrograms 1(-1). Therefore, it is suggested that GH levels of 80-100 micrograms 1(-1) maximally activate Somatomedin-C production in man and that further increases in GH in general will not result in a further increase in SM-C generation. There was a significant correlation between GH and SM-C levels in forty-nine acromegalic patients after surgery and/or radiotherapy (P less than 0.001). In twenty-three of thirty-one patients with elevated SM-C levels the disease was subjectively still active, while this was the case in none of the patients with normal SM-C levels. In eight patients the disease was considered not to be clinically active any more, despite slightly increased SM-C levels.(ABSTRACT TRUNCATED AT 250 WORDS)