Endocrine Abstracts

Background: Acromegaly results from excess growth hormone (GH) secretion by a pituitary adenoma in 95% of the cases. Discordant acromegaly is defined by the elevation of GH with normal levels of insulin-like growth factor type 1 (IGF-1) or normal levels of GH associated with an elevation of IGF-1. Its an important situation in the follow-up period of patients with acromegaly because there is little information about patient treatment, comorbidities and follow-up. The objective of this study was to describe the prevalence of discordant acromegaly after pituitary surgery, follow changes in GH and IGF-1 patterns over time and explore possible correlations with blood pressure and HbA1C.

Methods: We retrospectively analyzed the prevalence and characteristics of patients who had an elevated IGF-1 but normal GH or an elevation of GH with normal IGF-1, in consecutive post-surgical acromegaly cases from the year 2000 to 2015 at our institution. To define discordant acromegaly in our study hormonal evaluation was obtained at the 3 months post surgically (GH, and IGF-1). Discordant patients were categorized into two groups according to the postoperative GH and IGF-1: high IGF-1 group (normal GH and high IGF-1), high GH group (high GH and normal IGF-1). We followed discordant patients at 6 and 12 months with GH, IGF-1, magnetic resonance (only at 6 months), blood pressure and HbA1c.

Results: The prevalence of discordant acromegaly was 11.7% (9/77). Of this patient population 77.7% (7/9) changed their biochemical pattern after 12 months of follow-up. Of these, 11.3% (1/9) in the high GH group became inactive, 66.6% (6/9) became active (high IGF-1 group), and 22.2% (2/9) remained discordant (both in the high GH group) and had normal suppression of GH to glucose. Positive correlations were found between the level of IGF-1 at 6 months with systolic blood pressure (R=0. 89, P=0. 001) and diastolic blood pressure (R=0.891; P=0.002). No correlation was found between GH, IGF-1 and HbA1c or tumor size.

Conclusions: Discordant acromegaly in the postsurgical state is a rare entity, with variation in hormonal patterns at 12-month follow up and a positive correlation with blood pressure levels. We suggest that this patients need to be carefully followed due to the high likelihood of recurrence, particularly if the elevation is of IGF-1 and with the presence of residual tumor.