Assessment of ACTH assay variability: a multicenter study

ObjectiveMeasurement of plasma ACTH plays a pivotal role in the diagnosis and treatment of several endocrine disorders. Little is known, however, on the variability of ACTH assay results and its impact on clinical practice. The aim of the present study was to assess the performance of routine plasma...

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Bibliographic Details
Published in:European journal of endocrinology 2011-04, Vol.164 (4), p.505-512
Main Authors: Pecori Giraldi, Francesca, Saccani, Andrea, Cavagnini, Francesco
Format: Article
Language:English
Subjects:
Adrenocorticotropic Hormone - blood
Biological and medical sciences
Biological Assay - standards
Clinical Study
Endocrinopathies
Fundamental and applied biological sciences. Psychology
Humans
Medical sciences
Reproducibility of Results
Vertebrates: endocrinology
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Summary:ObjectiveMeasurement of plasma ACTH plays a pivotal role in the diagnosis and treatment of several endocrine disorders. Little is known, however, on the variability of ACTH assay results and its impact on clinical practice. The aim of the present study was to assess the performance of routine plasma ACTH measurements.DesignTwenty-five fresh-frozen plasma samples collected from patients with either high, low, or normal ACTH concentrations were measured using seven different assays by 35 different laboratories. Assay precision, method agreement, and result classification were estimated.ResultsInter- and intra-assay coefficient of variation varied considerably with some assays achieving 20%. Overall method agreement was good (mean ratio versus target value 1.02) but subject to exceedingly large excursion (lower and upper limits of agreement at 0.13 and 1.91 respectively). Both differences between assays and between laboratories contributed to variability of method agreement. Assays correctly classified most patients with normal and high ACTH concentrations (90% (95% CI 82–97%) and 95% (95% CI 86–100%) respectively), whereas only 60% (95% CI 52–67%) of measurements from patients with low ACTH values were assigned correctly.ConclusionsField ACTH assays have to be interpreted with caution as they are burdened by high variability and often fail to correctly identify patients with suppressed ACTH secretion. The endocrine community has to include ACTH assays among those requiring standardization.
ISSN:0804-4643
1479-683X
DOI:10.1530/EJE-10-0962