Endocrine Abstracts

Introduction: Increased GH and IGF-1 levels in acromegaly results in several micro and macrovascular changes. There are controversial results about the effects of GH/IGF-1 on retinal vasculature. Gremlin-1 is a BMP-4 antagonist which binds to VEGFR to activate its pathway and has demonstrated angiogenic properties on several tissues. We aimed to detect retinal changes in acromegaly and examine its association with serum gremlin-1 levels.

Methods: We included 53 acromegaly patients and matched 30 healthy controls. For the evaluation of deep and superficial vascular density and foveal avascular zone (FAZ) OCTA imaging was performed by Optovue (Fremont, CA). Gremlin -1 levels were measured by ELISA method.

Results: Deep (P > 0.001) and superficial foveal densities (P = 0.002) were significantly lower in acromegaly patients compared to controls. Additionally perifoveal retinal thickness was significantly reduced compared to controls (P = 0.027). Plasma gremlin -1 levels were significantly lower in the acromegaly group (P = 0.015). No significant difference was detected between active acromegaly (n = 32) vs controlled acromegaly (n = 21). GH and IGF were negatively correlated with superficial foveal density (r = -0,242 P = 0,046; r = 0,-263 P = 0,028) Deep foveal density was negatively correlated with GH and IGF (r = -0,239 P = 0,005; r = -0,241 P = 0,045) A negative correlation was detected between Gremlin and FAZ (r = -0,242 P = 0,035) All participants were evaluated in terms of glucose tolerance status.

Conclusion: Besides the elevations in GH and IGF-1, metabolic alterations like glucose intolerance, hypertension, hyperlipidemia also effects vascular structure and function. In our study, parameters of vascular density were found lower in acromegaly group compared to controls. This indicates a reduction in retinal vessel density. Also it is of note that vascular density is negatively correlated with GH/IGF. In terms of metabolic alterations, vascular density was still significantly lower when the groups were categorized for glucose intolerance. Gremlin, which is considered as an angiogenic molecule, was also lower in acromegaly.