Value of growth hormone dynamics and somatomedin C (insulin-like growth factor I) levels in predicting the long-term benefit after transsphenoidal surgery for acromegaly.

Transsphenoidal microsurgery has been shown to be effective in the management of human growth hormone (hGH)-secreting pituitary adenomas. We have previously demonstrated the usefulness of hGH dynamic testing (oral glucose tolerance, insulin hypoglycemia, and thyrotropin-releasing hormone stimulation test) in evaluating the completeness of removal of the adenomas. In patients with acromegaly, serum insulin-like growth factor I (IGF-I) levels are known to correlate with the activity of the disease. We studied the dynamics of hGH secretion in 43 patients with hGH-secreting adenomas 2 to 3 months after surgery. In addition, serum IGF-I levels were recently measured in frozen sera obtained from these patients at the time of dynamic testing. Of the 43 patients undergoing surgery, 19 had normal basal hGH levels as well as dynamics (group I). Two additional patients had low or undetectable hGH levels and were hypopituitary (group II). These 21 patients were considered cured and had no evidence for recurrence of their disease during a mean follow-up period of 97 months. Serum IGF-I levels were normal in 19 (group I) and low in the remaining two patients (group II). Nine additional patients had normal basal hGH levels but abnormal dynamics of secretion (group III). Serum IGF-I levels were normal postoperatively in seven of eight patients tested in this group. During the follow-up period in these nine patients (group III), biochemical and clinical recurrence of acromegaly developed in five. The remaining 13 patients had persistent elevation of basal hGH levels, and all samples tested (n = 8) had elevated IGF-I levels.(ABSTRACT TRUNCATED AT 250 WORDS)