The ongoing challenge of discrepant growth hormone and insulin-like growth factor I results in the evaluation of treated acromegalic patients: a systematic review and meta-analysis.
OBJECTIVE
Growth hormone (GH) and insulin-like growth factor I (IGF-I) are the principal biomarkers used to assess disease activity in acromegaly, and any discrepancy between them renders interpretation of results inconclusive. Purpose of this study was to assess the frequency of this discrepancy and identify parameters that might affect its occurrence.


METHODS
A systematic review of MEDLINE and Scopus was performed (1987-2013) followed by a meta-analysis to address the frequency of discrepant results between GH and IGF-I levels. Meta-regression and subgroup analyses were performed assessing the effects of the year of publication, the different types of GH testing and GH assays used, as well as the impact of treatment with somatostatin analogues (SSAs) on the occurrence of this discrepancy.


RESULTS
The analysis retrieved 39 eligible studies totalling 7071 patients. The pooled discordance rate between GH and IGF-I was 25·7% (95% CI: 22·3-29·4), and the predominant format was that of elevated IGF-I with normal GH levels (15·3%, 95% CI: 12·5-18·7). No significant correlation between the discordance rate and the year of publication was shown; whereas, the use of ultrasensitive GH assays resulted in higher discordance rates (30·7%, 95% CI: 25·9-35·9 vs 19·8%, 95% CI: 14·1-27·2, P = 0·04) as did treatment with SSAs (32·5%, 95% CI: 27·8-37·4) vs (21·6%, 95% CI: 17·8-25·6, P = 0·001).


CONCLUSIONS
Discrepancy between GH and IGF-I results is encountered in a quarter of treated patients with acromegaly, especially when using ultrasensitive GH assays or in patients receiving SSAs, a fact that the clinician should take into consideration when making clinical decisions.
Department of Endocrinology, Athens Naval & VA Hospital, Athens, Greece. geokan@endo.gr.
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http://orcid.org/0000-0002-3526-8379
GA
Kanakis
Department of Endocrinology, Theagenio Cancer Hospital, Thessaloniki, Greece.
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A
Chrisoulidou
Department of Endocrinology and Metabolic Diseases, University of Thessaly, Larissa, Greece.
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A
Bargiota
Department of Endocrinology, 'Hippokration' General Hospital of Thessaloniki, Thessaloniki, Greece.
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ZA
Efstathiadou
Department of Endocrinology and Diabetes Center, Athens General Hospital 'G. Gennimatas', Athens, Greece.
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L
Papanastasiou
Division of Endocrinology, Department of Internal Medicine, University Hospital of Patras, Rio, Greece.
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A
Theodoropoulou
Department of Endocrinology, University of Ioannina, Ioannina, Greece.
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Tigas
Endocrine Unit, 2nd Department of Internal Medicine - Propaedeutic, Research Institute and Diabetes Center, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
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DA
Vassiliadi
Department of Endocrinology, Evangelismos Hospital, Athens, Greece.
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S
Tsagarakis
Endocrine Unit, Department of Medical Therapeutics, Medical School, University of Athens, Athens, Greece.
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Alevizaki
D000172:Acromegaly / Q000175:diagnosis*; D015415:Biomarkers / Q000032:analysis; D013006:Growth Hormone / Q000032:analysis*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*
D015415:Biomarkers; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone