Abstract
Background: The diagnosis of acromegaly still poses a clinical challenge, and prolonged diagnostic delay is common. The most important assays for the biochemical diagnosis and management of acromegaly are growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Objective: Discuss the role of IGF-1, basal serum GH, and nadir GH after oral glucose tolerance test (OGTT) for the diagnosis, management, and treatment of patients with acromegaly. Methods: We performed a narrative review of the published data on the biochemical diagnosis and monitoring of acromegaly. An English-language search for relevant studies was conducted on PubMed from inception to 1 January 2021. The reference lists of relevant studies were also reviewed. Results: Serum IGF-1 levels, basal GH values, and nadir GH after OGTT play a major role in the diagnosis, management, and treatment of patients with acromegaly. Measurement of IGF-1 levels is the key factor in the diagnosis and monitoring of acromegaly, but basal and nadir GH following OGTT are also important. However, several factors may significantly influence the concentrations of these hormones, including assay methods, physiologic and pathologic factors. In some cases, discordant GH and IGF-1 levels may be challenging and usually requires additional data and monitoring. Conclusion: New GH and IGF-1 standards are much more precise and provide more accurate tools to diagnose and monitor patients with acromegaly. However, all these biochemical tools have their limitations, and these should be taken under consideration, along with the history, clinical features and imaging studies, when assessing patients for acromegaly.
Highlights
Is a slowly progressive disease caused by persistent excess of circulating growth hormone (GH) and insulin-like growth factor-1 (IGF-1) [1]
While most cases are secondary to a GH-secreting pituitary adenoma, acromegaly may rarely be secondary to a hypothalamic secreting GH-releasing hormone (GHRH) or ectopic GHRH or GH
While it was previously considered as the gold standard for the diagnosis of acromegaly, suppression of GH levels during oral glucose tolerance test (OGTT) is not specific for acromegaly, as conditions associated with an abnormal GH response to a glucose load include severe catabolic illness, malnutrition, renal or hepatic failure, uncontrolled diabetes mellitus, Laron type dwarfism
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. While over the years there have been improvements in the diagnostic procedures for acromegaly, including the availability of serum IGF-1 measurement and more sensitive GH assays, the diagnostic delay and the age at diagnosis have not changed, and that is mostly secondary to the insidious onset of the clinical features, overlap of the signs and symptoms with other common conditions, and lack of disease awareness among other medical specialists [5,7]. This diagnostic delay is considerably shorter compared with mean delays in diagnosis of 16–18 years after symptom onset reported half a century ago [8]. While serum IGF-1 levels, basal GH values, and nadir GH after OGTT play a major role in the diagnosis, management, and treatment of patients with acromegaly, the limitations of these tests should be acknowledged for optimal use
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