Early postoperative indicators of late outcome in acromegalic patients.

OBJECTIVE: According to current criteria, normalised serum IGF-1 and glucose-suppressed GH < 1 ng/ml are indicators of biochemical cure in acromegalic patients. We performed a retrospective study to assess whether the attainment of these values in the early postoperative period was predictive of future IGF-1 normalisation and disease inactivity. PATIENTS, MEASUREMENTS AND
RESULTS: Between 1978 and 1999, 78 acromegalic patients underwent resection for pituitary adenomas. At the end of the mean follow-up period of 7 years, 43 (55.1%) showed normalised IGF-1 levels and no disease activity. In 51 cases, both IGF-1 and glucose-suppressed GH were examined within the first postoperative month. Of this group, all 19 patients who had early glucose-suppressed GH < 1 ng/ml and were treated by surgery alone maintained normal IGF-1 levels throughout the follow-up; four of them demonstrated delayed (i.e. more than 30 days after the operation) IGF-1 normalisation. In 19 patients with early glucose-suppressed GH levels of 1-4 ng/ml, seven of 11 patients with early normalised IGF-1 and two of eight patients with early IGF-1 elevation manifested eventual IGF-1 normalisation. However, none of the 13 patients with early glucose-suppressed GH > 4 ng/ml attained IGF-1 normalisation. Both univariate and multivariate analyses indicated that early glucose-suppressed GH was a significant factor for predicting late normalised IGF-1; the cut-off value was 1.5 ng/ml (sensitivity: 0.97; specificity: 0.75; odds ratio: 90).
CONCLUSION: The attainment of both normalised IGF-1 and glucose-suppressed GH < 1 ng/ml, even during the early postoperative period, suggests absolute cure in acromegalic patients. However, even in patients who do not meet both criteria within the first postoperative month, glucose-suppressed GH < 1.5 ng/ml, or glucose-suppressed GH < 4 ng/ml coupled with early IGF-1 normalisation indicate the possibility of eventual normalisation of IGF-1 and disease inactivity without adjuvant therapy. These postoperative parameters may be useful for assessing the desirability of further treatment.