An audit of the laboratory interpretation of growth hormone response to                insulin-induced hypoglycaemia in the assessment of short stature in                children

Ellis, Andy; Seth, John; Al-Sadie, Ruth; Barth, Julian H.

doi:10.1258/000456303321610538

Cited by 8 publications

(6 citation statements)

References 8 publications

(10 reference statements)

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“…For GH, Andersson et al (5) illustrated how laboratories transfer cutoffs to new methods while ignoring known biases in the process, in effect, sustaining historical databases that are of little diagnostic merit. Ellis et al (6) illustrated the impact of using out-of-date cutoffs with the outcome of an interpretive exercise for an insulin tolerance test for GH deficiency in which 10% of 52 laboratories would have reported an "equivocal response" or "partial deficiency," even though the mean peak GH level was 32.8 mU/ liter. The use of a variety of factors for converting g/liter to mU/liter is an additional unnecessary complexity that hinders data interpretation.…”

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confidence: 99%

Harmonizing Growth Hormone Measurements: Learning Lessons for the Future

Wieringa

Trainer

2007

The Journal of Clinical Endocrinology & Metabolism

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Diagnosis and management of disease is increasingly driven by international efforts at consensus statements based on evidence of best practice. For endocrinology, diagnostic criteria based on the results of biochemical testing have for many years formed the mainstay to objective decision making, a recognition that biomarkers correlate better with morbidity and mortality risk than do signs, symptoms, and anthropometric parameters. Such testing becomes of increasing significance in an era of closer clinical scrutiny and accountability, and dictates the need for accurate, reliable results. But how strong is the evidence base for the diagnostic cutoff levels deployed in, for example, the investigation of GH secretion disorders? Our conclusion in reviewing GH assays'

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confidence: 99%

Harmonizing Growth Hormone Measurements: Learning Lessons for the Future

Wieringa

Trainer

2007

The Journal of Clinical Endocrinology & Metabolism

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“…6 This may contribute to the widespread confusion regarding appropriate cut-offs for GH deficiency. 7,8 We have shown that the relationship between assays remains constant for values <20 μ g/L (60 mU/L) even after stimulation. The negative bias of the recalibrated assay at concentrations >20 μ g/L (60 mU/L) should not compromise the clinical interpretation of results.…”

Section: Discussionmentioning

confidence: 89%

Standardization of the IMMULITE systems growth hormone assay with the recombinant IS 98/574

Barth

Sibley

2008

Ann Clin Biochem

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Background: The diagnosis of disorders of growth hormone (GH) secretion is based on the measurement of GH before and after dynamic stimulation or suppression tests. Over the years, specific cut-off values have been proposed without taking account of the considerable variation in results obtained using different methods for analysing GH. Recent publications have recommended the standardization of GH assays using IS 98/574, which is calibrated in mass and units (U). The IMMULITE range of GH assays have been recalibrated using this standard. Methods: We analysed 745 samples using the current and the restandardized GH assay kits. This series of samples contained 90 stimulation tests and seven suppression tests. Results:The data comparing the current and restandardized assays show a similar relationship for both basal and stimulated GH values for all IMMULITE platforms. There is a negative bias by the restandardized assay above approximately 20 mg/L. A conversion can be derived from this study which would mean that patient GH results expressed in milliunits per litre of IMMULITE in-house derived standard will be approximately three-fold of that expressed in micrograms per litre of IS 98/574. Conclusion: Use of IS 98/574 offers standardized reporting in microgram per litre IS 98/574. This will permit compliance with the consensus recommendations and the development of a firm evidence base for defining decision-making GH values.

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“…Unfortunately, these prerequisites cannot be fulfilled, as GH is heterogeneous, the biological activity of various GH forms is not constant, differences exist in the specificity of assays and several reference materials are in use. Consequently, method-based differences exist in clinical cut-off values used for the confirmation of diagnosis of GH deficiency [13] and for the diagnosis and follow-up of treatment balance in acromegalic patients [23] A recent audit of the laboratory interpretation of GH results in an insulin stress test showed that some laboratories were using cut-off concentrations that were unrelated to the bias of their GH assay [24]. Frequent changes of assay method may also confuse the clinician and lead to incorrect interpretation.…”

Section: Discussionmentioning

confidence: 99%

Problematic determination of serum growth hormone: Experience from external quality assurance surveys 1998–2003

Mörsky

Tiikkainen²,

Ruokonen

et al. 2005

Scandinavian Journal of Clinical and Laboratory Investigation

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The objective of the present study was to start a new external quality assurance survey (EQAS) for the determination of serum growth hormone (GH) using pooled serum specimens as quality-assurance samples. To give good coverage of multiple forms of GH, the specimens included sera from GH-deficient and acromegalic patients as well as from persons showing a normal response in GH provocation tests. In one survey the quality-control specimens were spiked with exogenous 22-kD GH to obtain some idea of the specificity and GH recovery of the assays. The EQA surveys of 1998-2003 were organized by Labquality of Helsinki in cooperation with three university hospital laboratories in Finland. The number of participating laboratories ranged from 8 to 14. During 1998-2003, gratifying methodological harmonization occurred in the participating group, as the participants switched to the immunometric detection principle, the number of method applications decreasing from 7 to 3. In 1998 the 14 participating laboratories reported five different conversion factors (from microg/l to mU/l), whereas in 2003 7 of the 8 participants reported the same factor. Despite the harmonization trend among participating laboratories, further efforts are needed, because marked method-based differences still exist. This dialogue should include kit manufacturers, laboratory experts, EQA organizations and clinicians using the test results.

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An audit of the laboratory interpretation of growth hormone response to insulin-induced hypoglycaemia in the assessment of short stature in children

Abstract: Introduction Measurement of serum growth hormone (GH) concentration in response to insulin-induced hypoglycaemia remains an important investigation in the assessment of pituitary disease.

Cited by 8 publications

References 8 publications

Harmonizing Growth Hormone Measurements: Learning Lessons for the Future

Harmonizing Growth Hormone Measurements: Learning Lessons for the Future

Standardization of the IMMULITE systems growth hormone assay with the recombinant IS 98/574

Problematic determination of serum growth hormone: Experience from external quality assurance surveys 1998–2003

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