ABSTRACT
Introduction
Acromegaly is a rare disorder characterized by the excessive secretion of growth hormone (GH), mostly caused by pituitary adenomas. While in full-blown cases the diagnosis is easy to establish, milder cases are more challenging. Additionally, establishing whether full cure after surgery is reached may be difficult.
Areas covered
In this article, we will review the challenges posed by the variability in measurements of GH and its main effector insulin-like growth factor I (IGF-I) due to both biological changes, co-morbidities, and assays variability.
Expert opinion
Interpretation of GH and IGF-I assays is important in establishing an early diagnosis of acromegaly, in avoiding misdiagnosis, and in establishing if cure is achieved by surgery. Physicians should be familiar with the variables that affect measurements of these 2 hormones, and with the performance of the assays available in their practice.
Article highlights
With use of monoclonal antibodies and calibration standards, GH and IGF-I assays have evolved over the years becoming more accurate
Despite improvements, there is often poor reproducibility between different assays
Knowledge of the accuracy of the assays is mandatory for clinicians ordering these tests
While in severe cases the biochemical diagnosis of acromegaly is obvious, in milder cases there is need for a glucose suppression test
The cut-off of GH nadir after glucose is debated, but probably lower than recommended by published guideline
Body mass index, sex, use of oral estrogen and glucose status influence the post-glucose GH nadir
Serum IGF-I may take long time to normalize after surgery, and post glucose suppression helps in establishing if surgical cure has been achieved.
Reviewer disclosures
Peer reviewers on this manuscript have no relevant financial or otherrelationships to disclose.
Declaration of interest
The authors have no relevant affiliations or financial involvement with anyorganization or entity with a financial interest in or financial conflict withthe subject matter or materials discussed in the manuscript. This includesemployment, consultancies, honoraria, stock ownership or options, experttestimony, grants or patents received or pending, or royalties.