Abstract
ObjectiveIn rare disease research, most randomized prospective clinical trials can only use limited number of patients and are comprised of highly heterogeneous populations. Therefore, it is crucial to report the results in such a manner that it allows for comparison of treatment effectiveness and biochemical control between studies. The aim of this review was to investigate the current methods that are being applied to measure and report growth hormone (GH) and insulin-like growth factor-1 (IGF-1) as markers for drug effectiveness in clinical acromegaly research.Search strategyA systematic search of recent prospective and retrospective studies, published between 2012 and 2017, that studied the effects of somatostatin analogues or dopamine agonists in acromegaly patients was performed. The markers of interest were GH, IGF-1, and the suppression of GH after an oral glucose tolerance test (OGTT). Additionally, the use of pharmacokinetic (PK) measurements in these studies was analyzed. The sampling design, cut-off for biochemical control, reported units, and used summary statistics were summarized.ResultsA total of 49 articles were selected out of the 263 screened abstracts. IGF-1 concentrations were measured in all 49 studies, GH in 45 studies, and an OGTT was performed in 11 studies. A wide range of different cut-off values and sampling designs were used to determine biochemical control in acromegaly patients. The summary statistics were reported in various ways, with the percentage of biochemical control most frequently used. Nine studies sampled the PK at one or more time points. Non-compartmental analyses were commonly performed on the available PK data.ConclusionsThe way GH and IGF-1 are measured and reported in acromegaly research varies considerably. A consensus on how to report study results would enable better comparisons between studies, thereby improving evidence based decision making to optimize treatment in acromegaly.
Highlights
Is a rare disease characterized by growth hormone (GH) hypersecretion that results in the abnormal growth of extremities, high morbidity, and an increased mortality risk
Binding of GH to GH-receptors located in the liver induces insulin-like growth factor-1 (IGF-I) synthesis and secretion into the circulation
The most common way of reporting the biomarkers concentrations in the included studies was a mean ± standard deviation (SD), which was reported in 42% of the insulin-like growth factor-1 (IGF-1) studies and in 41% of the GH studies
Summary
Is a rare disease (prevalence of 60–70 per million [1]) characterized by growth hormone (GH) hypersecretion that results in the abnormal growth of extremities, high morbidity, and an increased mortality risk. Pituitary (2018) 21:310–322 cases, acromegaly is the result of a GH secreting pituitary adenoma [2–4]. GH is secreted in discrete bursts that result in a pulsatile plasma GH concentration–time profile. GH secretion is mainly upregulated by growth hormone-releasing hormone (GHRH), GH-releasing peptide (GHRP, e.g. ghrelin), and inhibited by somatostatin. Binding of GH to GH-receptors located in the liver induces insulin-like growth factor-1 (IGF-I) synthesis and secretion into the circulation. Negative feedback on GH secretion is mediated by IGF-1 and by GH itself [5]. Major negative determinants of GH secretion are aging and adiposity, while on the other hand aromatizable sex steroids amplify GH secretion [6, 7]
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