Long-term evaluation of postoperative acromegalic patients in remission with previous and newly proposed criteria

Criteria to define remission of acromegaly have changed over years. Since 2000, criteria for cure are normal IGF-I levels and a nadir GH after oral glucose tolerance test (OGTT) of less than 1 μg/liter, although recent studies have suggested to lower this cutoff value. This study reevaluated long-term disease activity of acromegalic patients, who were previously considered in remission, using these criteria. The study included 70 of 146 patients operated on between 1984 and 1996 who were considered cured based on normal IGF-I levels, GH values less than 2.5 μg/liter, and/or disappearance of abnormal GH response to TRH/GnRH. Among these 70 patients, 16 were lost to follow-up, three died, and 11 (one of whom had disease recurrence) only gave a phone interview. Forty patients participated in the study and were reevaluated for IGF-I levels and post-OGTT GH nadir after 14.3 ± 4.2 (mean ± SD) yr from surgery. In all patients, normal IGF-I levels and a post-OGTT GH nadir of less than 1 μg/liter were found. In particular, 19 patients had a GH nadir of less than 0.19 μg/liter, i.e. the upper limit (mean + 2 SD) found in 30 controls, whereas 21 patients had a nadir between 0.19 and 0.77 μg/liter. No significant differences in hormonal parameters and comorbidities between the two subgroups were observed. These data showed that lowering the post-OGTT GH cutoff value within the normal range does not seem to better discriminate patients with different disease activity or long-term recurrence risk.