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Wieringa GE, Sturgeon CM, Trainer PJ. The harmonisation of growth hormone measurements: taking the next steps. Clin Chim Acta 2014; 432:68-71. [PMID: 24509000 DOI: 10.1016/j.cca.2014.01.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 01/08/2014] [Accepted: 01/08/2014] [Indexed: 11/30/2022]
Abstract
For over 20 years differences in results of growth hormone (GH) measurement have been recognised as being significant enough to lead to misdiagnosis and inappropriate management of patients with GH-related disorders. Whilst issues of method standardisation, variable antibody specificity, use of different reporting units with different conversion factors, and interference from GH binding protein have been acknowledged as contributing to the discrepancies, inconsistent approaches to method harmonisation have hampered opportunities to enhance the evidence base for GH measurements. Amongst the first steps to be taken, international collaboratives recommended the universal adoption of the International Standard 98/547 and the reporting of results in mass units. Whilst inter-method variability may have improved over the last 10 years, clinically significant differences remain. A more recently recognised issue contributing to the discrepancies may be the differences in the matrix materials used by kit manufacturers to assign values to their calibrants. The establishment of an international harmonisation oversight group is recommended: its key roles to include identification of a commutable matrix reference material, assessing the clinical significance of assay interferents, the evaluation of liquid chromatography-mass spectrometry as a reference measurement procedure and the provision of acceptance criteria for the clinical application of GH methods.
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Affiliation(s)
- Gilbert E Wieringa
- Department of Biochemistry, Bolton NHS Foundation Trust, Minerva Road, Farnworth, Bolton BL4 0JR, UK.
| | - Catharine M Sturgeon
- UK NEQAS [Edinburgh], Department of Laboratory Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK
| | - Peter J Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, UK
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Chaler EA, Ballerini G, Lazzati JM, Maceiras M, Frusti M, Bergada I, Rivarola MA, Belgorosky A, Ropelato G. Cut-off values of serum growth hormone (GH) in pharmacological stimulation tests (PhT) evaluated in short-statured children using a chemiluminescent immunometric assay (ICMA) calibrated with the International Recombinant Human GH Standard 98/574. Clin Chem Lab Med 2013; 51:e95-7. [DOI: 10.1515/cclm-2012-0505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/26/2012] [Indexed: 11/15/2022]
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Rigamonti AE, Bozzola M, Banfi G, Meazza C, Müller EE, Cella SG. Growth hormone variants: a potential avenue for a better diagnostic characterization of growth hormone deficiency in children. J Endocrinol Invest 2012; 35:937-44. [PMID: 23027770 DOI: 10.3275/8647] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human GH (hGH) is a heterogeneous protein hormone consisting of several isoforms. This heterogeneity is the consequence of multiple hGH genes, mRNA splicing, post-translational modifications, and peripheral metabolism, and it represents one important reason for the disparity among GH assay results from different laboratories. However, other factors are involved: a) interference from endogenous GH binding proteins; b) different specificities of anti- GH (monoclonal and polyclonal) antibodies; c) different matrix effects among the calibrators; d) the use of different calibrators. The measurement of GH levels in response to provocative testing is an essential part of the diagnosis of GH deficiency. For this purpose, an accurate, reproducible and universally valid GH measurement would be highly desirable, but, despite a huge number of efforts in clinical biochemistry, this goal remains elusive.
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Affiliation(s)
- A E Rigamonti
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy.
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Manolopoulou J, Alami Y, Petersenn S, Schopohl J, Wu Z, Strasburger CJ, Bidlingmaier M. Automated 22-kD growth hormone-specific assay without interference from Pegvisomant. Clin Chem 2012; 58:1446-56. [PMID: 22908135 DOI: 10.1373/clinchem.2012.188128] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Large variability exists among different growth hormone (GH) assays owing to differences in calibration, antibody specificity, isoform recognition, and interference from GH binding protein (GHBP). The GH receptor antagonist Pegvisomant presents a new challenge because Pegvisomant interferes with many GH assays. A recent consensus conference established criteria for standardization and evaluation of GH assays. Following consensus recommendations, we developed a new GH assay on an automated analyzer (IDS-iSYS, Immunodiagnostic Systems). METHODS A monoclonal antibody not cross-reacting with Pegvisomant was combined with a monoclonal antibody specific for 22-kD GH. Isoform specificity and interference from GHBP was tested and compared to that seen in 2 existing automated GH assays (Siemens Immulite, Diasorin Liaison). We also compared GH concentrations measured by the 3 assays for healthy volunteers and patients with acromegaly receiving different treatments. Using the iSYS assay, we also established nadir GH values during oral glucose load and analyzed changes in endogenous GH during Pegvisomant treatment. RESULTS Analytical and functional sensitivities were 0.01 μg/L and 0.04 μg/L, with a dynamic range from 0.04 to 100 μg/L. Intraassay CVs were 2%-4%, whereas interassay CVs were 5%-7% at GH concentrations between 1.7 and 27.5 μg/L. The assay was specific for 22-kD GH and not affected by GHBP. The presence of Pegvisomant, which leads to a negative bias on the Immulite and dramatic overestimation of GH on the Liaison, had no impact on the iSYS GH assay. CONCLUSIONS The new assay fulfils recent consensus recommendations and presents a useful new tool for reliable measurement of GH.
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Affiliation(s)
- Jenny Manolopoulou
- Endocrine Research Laboratories, Medizinische Klinik und Poliklinik IV, Ludwig Maximilians University, Munich, Germany
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Pagani S, Meazza C, Laarej K, Cantoni F, Bozzola M. Efficacy of long-term growth hormone therapy in short children with reduced growth hormone biological activity. J Endocrinol Invest 2011; 34:366-9. [PMID: 21508660 DOI: 10.1007/bf03347461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
AIM The optimal GH regimen, in terms of cost-effectiveness, in children with normal GH immunoreactivity but reduced bioactivity is still debated. METHODS In 12 GH-deficient (GHD) and 12 bioinactive GH children undergoing GH treatment we evaluated the increase in growth velocity, the difference between target height and final stature and the incremental cost-effectiveness ratio. RESULTS We found a significant (p < 0.05) increase in growth velocity in both groups during the first year of GH treatment (non- GHD: from -1.7 to 5.4 SDS; GHD: from -1.46 to 4.74 SDS). There was no statistically significant variation between the two groups in the difference between final height and target height. We did not find any significant difference in cost/height gain between GHD (1925.28 ± 653.15 euro) and bioinactive GH children (1639.55 ± 631.44 euro). There were also no significant differences in cost/year of therapy between GHD (12347.68 ± 2018.1 euro) and bioinactive GH children (11355.08 ± 1747.61 euro). CONCLUSION In children with reduced GH biological activity, confirmed by the increase of serum IGF-I levels during generation test, the cost of GH treatment is justified by the positive results obtained in growth and adult height as in classical GHD patients.
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Affiliation(s)
- S Pagani
- Pediatrics Department, University of Pavia, IRCCS San Matteo Foundation, Pavia, Italy
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Pritchard C, Quaglia M, Mussell C, Burkitt WI, Parkes H, O'Connor G. Fully Traceable Absolute Protein Quantification of Somatropin That Allows Independent Comparison of Somatropin Standards. Clin Chem 2009; 55:1984-90. [DOI: 10.1373/clinchem.2009.124354] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background: Measurement traceability in clinical chemistry is required to standardize clinical results irrespective of the measurement procedure and laboratory. The traceability of many protein substances is maintained by reference to the first standard produced, which may no longer exist, with values assigned by consensus. Independent methods that provide traceability to the Système d’Unité International for all relevant properties of a protein standard could remove reliance on the original standard preparations.
Methods: We developed a method based on the traceable quantification of tryptic peptides released from the protein by isotope dilution mass spectrometry to compare 2 standard preparations of somatropin (recombinant human growth hormone), WHO 98/574 and Ph.Eur.CRS S0947000. Relative quantification using isotope-coded affinity tagging, isobaric tagging for relative and absolute quantification, and standard additions were also performed to validate the digestion method used and to determine whether any modifications were present.
Results: The total somatropin content in both materials was determined and an uncertainty estimation undertaken [WHO 2.19 ± 0.21) mg/vial, European Pharmacopeia 2.06 ± 0.21 mg/vial]. Each uncertainty in this paper is a fully estimated uncertainty, with 95% CI (k = 2). Isotope coded affinity tag and standard addition results fully validated the robustness of the digestion method used. In addition, iTRAQ (isobaric tagging for relative and absolute quantification analysis) identified 2 modifications, neither of which impacted the quantification.
Conclusions: An independent method that does not rely on a preexisting protein standard has been developed and validated for the traceable value-assignment of total somatropin. The methods reported here address the amount of substance (mass fraction) of the standard materials but address neither biological activity nor other characteristics that may be important in assessing suitability for use as a calibrator.
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Casagrande A, Czepielewski MA. Ensaios para a medida de hormônio do crescimento (GH) e IGF-I: aspectos metodológicos e suas implicações no diagnóstico e seguimento da acromegalia. ACTA ACUST UNITED AC 2007; 51:511-9. [PMID: 17684610 DOI: 10.1590/s0004-27302007000400003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 03/15/2007] [Indexed: 11/21/2022]
Abstract
A dosagem do GH no soro é essencial para confirmar ou excluir o seu excesso. Na acromegalia, a ausência de critérios clínicos suficientemente sensíveis para monitorizar o sucesso do tratamento faz com que o GH sérico seja o procedimento de escolha e, para isso, é essencial que a sua dosagem seja realizada de forma confiável, capaz de permitir interpretações uniformes. Vários critérios hormonais têm sido propostos para caracterizar remissão da acromegalia, incluindo níveis séricos de GH randômico inferior a 2,5 µg/l, nadir de GH durante o teste de tolerância oral a glicose inferior a 1,0 µg/l e IGF-I normal para sexo e idade. A importância do tratamento adequado consiste na possibilidade de reverter a mortalidade prematura da acromegalia através da diminuição dos níveis de GH para valores menores que 2,5 µg/l. Com o surgimento de ensaios ultra-sensíveis para medida do GH, tornaram-se necessários critérios mais estritos para determinar cura ou remissão da doença. Nesta revisão, descreveremos aqui as modificações decorrentes da evolução dos ensaios, as conseqüências nos resultados de GH e os pontos de corte propostos na literatura para caracterização da atividade e remissão da acromegalia.
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Affiliation(s)
- Alessandra Casagrande
- Programa de Pós-Graduação em Ciências Médicas: Endocrinologia, Hospital de Clínicas de Porto Alegre, Faculdade de Medicina, UFRGS, Rua Ramiro Barcelos 2350, 90035-003 Porto Alegre, RS.
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Chaler EA, Rivarola MA, Guerci B, Ciaccio M, Costanzo M, Travaglino P, Maceiras M, Pagani S, Meazza C, Bozzola E, Barberi S, Bozzola M, Belgorosky A. Differences in serum GH cut-off values for pharmacological tests of GH secretion depend on the serum GH method. Clinical validation from the growth velocity score during the first year of treatment. HORMONE RESEARCH 2006; 66:231-5. [PMID: 16912509 DOI: 10.1159/000095005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Accepted: 06/20/2006] [Indexed: 11/19/2022]
Abstract
BACKGROUND The serum GH cut-off value for pharmacological tests of GH secretion (PhT GH) depends on the type of test and also on the method used for determining serum GH. Cut-off serum GH values as different as 5-10 ng/ml, have been reported, and have been validated biochemically. We have used the growth velocity (GV)-standard deviation score (SDS) during the first year of treatment with rhGH to validate these cut-offs on a biological basis. METHODS Fifty pre-pubertal patients with short stature (height < or =-2 SDS and GV < or =-1.2 SDS) were studied. GH deficiency (GHD) was diagnosed in 39 patients, on the basis of clinical and auxological parameters and on the serum concentration of IGF-1, and non-GHD in the other 11 patients. Two PhT GH (arginine and clonidine) were carried out in the 50 patients. Serum GH was determined by two different methods: one detecting most of serum GH isoforms, named Total GH (HGH Bio-Tech, MAIA Clone), and another one, only detecting the 22 kDa GH, named 22K GH (GH-22K IFMA, Wallac). RESULTS Basal data: all patients with GHD and with non-GHD had maximal serum GH response (MaxR) values below and above the cut-off, respectively, for the serum Total GH and 22K GH. The mean 22K GH/Total GH ratio was similar to previous publications. Post-rhGH treatment data: the two groups improved their height SDS during the first year of treatment, particularly patients with GHD. A receiver-operator curve was used to define the best threshold for post-treatment GV-SDS that separates GHD from non-GHD patients. This value was 1.91 GV-SDS. A negative correlation between first year treatment GV-SDS and pre-treatment serum GH MaxR was found for the two assays (p < 0.001). Then, the best cut-off GV-SDS, previously calculated with the receiver-operator curve (1.91 SDS) was used to interpolate the corresponding serum GH values, as determined by the two methods. For Total GH, the value was 10.8 ng/ml, and for 22K GH, it was 5.4 ng/ml. CONCLUSION The cut-off values calculated by biological means to separate GHD from non-GHD were remarkably similar to those calculated biochemically (10.0 and 4.8 ng/ml, respectively) for Total and 22K GH. This is a biological validation for using different cut-off values, appropriate for each assay, to diagnose GHD.
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Affiliation(s)
- E A Chaler
- Servicio de Endocrinologia, Hospital de Pediatria Garrahan, Buenos Aires, Argentina.
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Markkanen H, Pekkarinen T, Välimäki MJ, Alfthan H, Kauppinen-Mäkelin R, Sane T, Stenman UH. Effect of sex and assay method on serum concentrations of growth hormone in patients with acromegaly and in healthy controls. Clin Chem 2006; 52:468-73. [PMID: 16439607 DOI: 10.1373/clinchem.2005.060236] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Diagnosis and follow-up of acromegaly is based on measurements of serum growth hormone (GH) concentrations during an oral glucose tolerance test (OGTT). A nadir value <1 microg/L is commonly used to define a normal response, but some authors suggest lower cutoff values. METHODS To compare the results and subsequent patient classification obtained with 3 GH assays, we obtained basal serum samples from 78 apparently healthy adult controls (43 women and 35 men; median age, 32.5 years) and from 71 treated (44 women and 27 men; median age, 55.2 years) and 7 untreated acromegaly patients (4 women and 3 men; median age, 54.6 years), and OGTT was performed on all patients and on 72 of the 78 controls. GH was determined by 2 immunometric assays-a double monoclonal (AutoDELFIA; Wallac) and a monopolyclonal (Immulite 2000; DPC) assay-and in a limited set of samples by an RIA (Spectria RIA; Orion). RESULTS There was a strong correlation (r = 0.995; P < 0.001) between the 2 immunometric methods, but the results obtained with the Immulite 2000 were, on average, 1.4-fold higher than those obtained with the AutoDELFIA. At concentrations around the cutoff (1 microg/L), however, the difference was approximately 2-fold. Overall, the Orion RIA method also showed a good correlation (r = 0.951-0.959) with the other methods, but it did not measure concentrations <2 microg/L. Women had higher basal and OGTT nadir GH concentrations than men. CONCLUSION Reference intervals should be determined separately for each method, and the need for establishing sex-specific reference values should be investigated.
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Affiliation(s)
- Helene Markkanen
- Department of Clinical Chemistry, Helsinki University Hospital, Helsinki, Finland.
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Affiliation(s)
- G E Wieringa
- Department of Biochemistry, Christie Hospital NHS Trust, Manchester, UK
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Nindl BC, Kraemer WJ, Marx JO, Tuckow AP, Hymer WC. Growth hormone molecular heterogeneity and exercise. Exerc Sport Sci Rev 2004; 31:161-6. [PMID: 14571954 DOI: 10.1097/00003677-200310000-00002] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There are more than 100 molecular isoforms of circulating growth hormone (GH), but the traditional measurement approach in the exercise literature has only focused on the main isoform (i.e., 22 kDa). New assay methodologies now can assess various GH isoforms. The current data suggest that exercise results in the preferential release of GH isoforms with extended half-lives, thereby sustaining biological actions.
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Affiliation(s)
- Bradley C Nindl
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA.
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Evans C, Gregory JW. The investigation of short stature: a survey of practice in Wales and suggested practical guidelines. J Clin Pathol 2004; 57:126-30. [PMID: 14747433 PMCID: PMC1770205 DOI: 10.1136/jcp.2002.002238] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To survey the investigation of short stature in Wales and suggest guidelines to improve practice. METHODS Questionnaires were circulated to paediatricians and consultant clinical biochemists or consultant chemical pathologists at 13 Welsh hospitals where children with short stature are investigated. RESULTS A 100% response was obtained from laboratory and clinical staff. Clinicians screened 1-50 patients each year (median, 10). Growth hormone (GH) deficiency was subsequently diagnosed in 0-30% (median, 10%) and GH treatment started in 30-100% (median, 100%) of patients. Five paediatricians and eight laboratories had written investigative protocols. Investigation of GH secretion was initiated in some centres before a complete clinical evaluation was carried out. Various screening tests for GH deficiency, including insulin-like growth factor 1 (IGF-1), random GH, and exercise tests were used. The clonidine stimulation test was used to assess the GH axis in most centres but eight different protocols were described. GH was measured in four Welsh laboratories using two automated immunoassay methods. However, nine different ranges of cutoff values for defining abnormal GH responses were quoted, and in three centres laboratories and paediatricians quoted different cutoffs. CONCLUSION This survey demonstrates the need for practical guidelines for the investigation and management of short stature in children, agreed by paediatricians and their laboratory colleagues. The guidelines should encompass the initial clinical investigation, assessment of the GH-IGF-1 axis (using standardised protocols), and provision for the transition to adult management. This article presents practical guidelines based on published points for good practice.
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Affiliation(s)
- C Evans
- Department of Medical Biochemistry, University Hospital of Wales, Cardiff, UK.
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Abstract
There is now considerable evidence that the clinical outcome in patients with acromegaly can be improved very substantially by means of better surgical expertise and effective medical therapies used in a flexible and innovative manner. Medical therapy alone in patients who have not undergone surgery or radiotherapy (primary medical therapy) offers the prospect of near normalisation of GH/IGF-I levels together with substantial tumour shrinkage in a significant number of patients.
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Affiliation(s)
- Michael C Sheppard
- Department of Medicine, Division of Medical Sciences, University of Birmingham, Birmingham, UK.
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