Standardization with Synthetic 22-KDa Monomer Human Growth Hormone Reduces Discrepancies Between Two Monoclonal Immunoradiometric Assay Kits

Abstract Discrepancies among different methods for assaying human growth hormone have been described in various studies. The two major sources of discordant results are the heterogeneity of the antibodies and the different standardization bases used by the assay manufacturers. We propose standardizing assays with 22-kDa biosynthetic monomer human growth hormone diluted with the diluents supplied by the kit manufacturers. In a study of two monoclonal immunoradiometric assays (Hybritech, specific for the 22-kDa monomer; Sorin, recognizing also a 20-kDa variant hormone), standardization with 22-kDa monomer human growth hormone reduced by 63% the differences in results for 44 serum samples from children. The use of 22-kDa human growth hormone as a common standard, highly pure and easily available in large quantities, could help limit the interpretative problems in growth diagnostics.

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Time-resolved immunofluorometric assay of human growth hormone

Clinical Chemistry ◽

10.1093/clinchem/39.8.1620 ◽

1993 ◽

Vol 39 (8) ◽

pp. 1620-1625 ◽

Cited By ~ 36

Author(s):

K Albertsson-Wikland ◽

C Jansson ◽

S Rosberg ◽

A Novamo

Keyword(s):

Growth Hormone ◽

Human Growth Hormone ◽

Polyclonal Antibodies ◽

Human Growth ◽

Immunoradiometric Assay ◽

Serum Samples ◽

Time Resolved ◽

Counting Time ◽

Pediatric Use ◽

The Eu

Abstract We describe a time-resolved immunofluorometric assay (trIFMA) for human growth hormone (hGH), in which monoclonal antibody (mAb)-coated microtiter strip wells and a europium (Eu) chelate-labeled mAb are used. We compare the new trIFMA, in which two mAbs are used, with an immunoradiometric assay (IRMA) in which polyclonal antibodies are used. Serum samples (n = 185) from 36 children with various diagnoses were analyzed. In addition, 24-h profile samples (72 per child) from 39 children were analyzed. The trIFMA was more sensitive (detection limit, 0.03 mIU/L) than existing IRMAs. Both the intra- and interassay CVs were < or = 10.6% for hGH concentrations between 1 and 100 mIU/L. The trIFMA is technically simple and rapid, requires no centrifugation or separation reagent, and has a counting time of only 1 s per sample. In addition, the Eu label is nontoxic, presents no waste-disposal problems, and has a long shelf-life. Finally, the assay requires only small volumes of serum (25 muL), which is of considerable importance in pediatric use. The mAbs used for the trIFMA selectively bind the 22-kDa form of hGH, with the result that the assay detects about 80% of the amount detected by the polyclonal IRMA.

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Performance of Proficiency Survey Samples in Two Immunoradiometric Assays of Human Growth Hormone and Comparison with Patients' Samples

Clinical Chemistry ◽

10.1093/clinchem/38.4.553 ◽

1992 ◽

Vol 38 (4) ◽

pp. 553-557 ◽

Cited By ~ 6

Author(s):

P J Pringle ◽

J Jones ◽

P C Hindmarsh ◽

M A Preece ◽

C G Brook

Keyword(s):

Growth Hormone ◽

Quality Assessment ◽

Human Growth Hormone ◽

Matrix Effect ◽

External Quality Assessment ◽

Human Growth ◽

Immunoradiometric Assay ◽

Serum Samples ◽

External Quality ◽

External Quality Assessment Scheme

Abstract The immunoradiometric assay (IRMA) used in our laboratory for the measurement of growth hormone (hGH; somatotropin) performed badly in the national proficiency survey program, the U.K. External Quality Assessment Scheme (EQAS). We compared our assay with another IRMA, which gave similar results for patients' samples and performed adequately in EQAS. The samples from EQAS are collected from patients with polycythemia and fall into two categories: those containing endogenous hGH and those supplemented with pituitary-derived hGH. Analysis of the two groups separately showed that the differences between the two IRMAS were in the measurement of the endogenous hormone. The reason for this appears to be a matrix effect related to the fact that the EQAS serum samples are collected from polycythemic patients.

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Gaps in the Traceability Chain of Human Growth Hormone Measurements

Clinical Chemistry ◽

10.1373/clinchem.2012.199489 ◽

2013 ◽

Vol 59 (7) ◽

pp. 1074-1082 ◽

Cited By ~ 14

Author(s):

Sébastien Boulo ◽

Katja Hanisch ◽

Martin Bidlingmaier ◽

Cristian-Gabriel Arsene ◽

Mauro Panteghini ◽

...

Keyword(s):

Growth Hormone ◽

Human Growth Hormone ◽

Human Growth ◽

Higher Order ◽

Serum Samples ◽

Traceability Chain ◽

Eu Directive ◽

In Vitro Diagnostic ◽

Relative Differences

BACKGROUND Human growth hormone (hGH) is measured for the diagnosis of secretion disorders. These measurements fall under the EU Directive 98/79/EC on in vitro diagnostic medical devices requiring traceability of commercial calibrator values to higher-order reference materials or procedures (Off J Eur Communities 1998 Dec 7;L 331:1–37). External quality assessment schemes show large discrepancies between results from different methods, even though most methods provide results traceable to the recommended International Standard (IS 98/574). The aim of this study was to investigate possible causes for these discrepancies. METHODS We investigated the commutability and recovery of hGH in reconstituted IS 98/574. We tested different reconstitution protocols and used 4 different serum matrices for spiking. These IS preparations were measured together with serum samples. We quantified hGH by 5 different methods in 4 different laboratories. RESULTS Results from the different methods correlated well for the serum samples. Mean discrepancies between results from different methods were ≤20%. None of the IS preparations was commutable for all the method comparisons. The recovery of hGH in preparations of IS 98/574 depended on the reconstitution protocol (>10-fold differences) and BACKGROUND matrix (relative differences ≤17% for different serum matrices). CONCLUSIONS The use of different protocols for reconstitution and spiking of hGH reference preparations affects quantification by immunoassays, potentially leading to a bias between commercial methods, despite the use of calibrators with values claimed to be traceable to the same higher-order reference material.

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