Endocrine Abstracts

Introduction

Treatment of choice in acromegaly is transsphenoidal resection of GH-secreting pituitary adenoma. Its efficacy ranges from 28% to 83% depending on tumor size and location. Random GH < 1 µg/l or nadir GH in OGTT < 0.4 µg/l and normal IGF-1 are found to be the evidence of effective surgery. However, some patients diagnosed with acromegaly remission after surgery present discordant GH and IGF-1 results.

Aim

Purpose of this study was to assess the frequency of discrepancy between GH and IGF-1 levels and identify parameters that might affect its occurrence.

Material and methods

Fourty seven patients (19 males, 40.4%) with acromegaly remission after pituitary surgery were included in the study. Random GH and IGF-1 measurements 3, 6, 12, 24 and more than 24 months after surgery were analyzed in terms of discrepancies. GH measurements in OGTT 3 months after surgery and later, if random GH > 1 µg/l, were performed. We defined discrepancy either as random GH > 1 µg/l or nadir GH > 0.4 µg/l in OGTT and normal IGF-1 or GH below levels listed before and elevated IGF-1. Clinical factors such as: sex, age, age at diagnosis, diagnosis delay, BMI, weight, tumour size, GH and IGF-1 at diagnosis and carbohydrate metabolism were analyzed in patients with and without GH and IGF-1 discrepancies. None of the patients required pharmacological treatment of acromegaly after surgery.

Results

The percentage of patients with GH and IGF-1 discrepancies was the smallest 3 months after surgery (42%), then increased 6 months after surgery (71%) and finally decreased over time (60% after 12 months, 55% after 24 months and 52% more than 24 months after surgery). The most frequent type of discrepancy was slightly elevated IGF-1 and random GH < 1 µg/l or nadir GH < 0.4 µg/l in OGTT (over 70% of patients with discordant GH and IGF-1 results within the first year after surgery). IGF-1 tended to decrease over time. Age, age at diagnosis, diagnosis delay, BMI, weight, tumor size, GH and IGF-1 at diagnosis were similar in patients with and without discrepancies (P > 0.05). A tendency to higher percentage of males in group with discrepancies was observed, 55% vs 30%, P = 0.08.

Conclusions

Discrepancy between GH and IGF-1 are common in patients with acromegaly remission after surgery affecting 42% to 71% of patients depending on time after surgery. Patients with GH and IGF-1 discrepancies should be observed, although the frequency of discrepancies decreases over time. Men may be more likely to present GH and IGF-1 discrepancies after effective adenomectomy.