Abstract
GH administration in GH-deficient patients is a well established therapy. At present, a cut-off level of 10μg/l for GH is widely accepted for detection of GH deficiency. But are the available GH assays sufficiently reliable yielding comparable results? For this purpose we have examined 5 commonly used commercial GH assays: 1. PR: Phamacia RIA, a 2-site IRHA using 2 polyclonal antibodies(AB) - 2. PD: Pharmacia Delphia, a 2-site fluoroimmunometric assay with 2 monoclonal AB.- 3. HV: Tandem-R HGH Hybritec, a 2-site IRHA with 2 Monoclonal AB.- 4. SE: Seria hGH Kit Serono, IRHA with 2 monoclonal AB.-5. HE: hGH-IRHA Hedgenix, with several monoclonal AB.
Results: Assay sensitivity was 0.01 μg/l for PD, 0.01 for PR, 0.075 for HY., 0.08 for ME and 0.25 μg/l for SE. The dilution of a plasaa containing 20 μg GH/L resulted in a linear decline in GH levels in all assays except for a small deviation in HY. For determination of assay precision 5 pooled plasmas were used with GH concentration of 2-4 μg/l, 4-8, 8-14, 9-19 and 12 to 28 μg/l: the interassay coefficient of variation (CV) was 5-8.7% for ME, 3.6-9.91 for PR, 5.6-13.3%. for PD, 4.95-8.4% for HY and 2.1-5.971 for SE; the intrassay CV was 2.8-6.21 for ME, 3.3-5.51 for PR, 3.7-8.51 for PD, 3.3-5.5% for HY and 1.3-2.5% for SE. Three commercial control sera (“Lyphochek”, Bio-Rad) were run in 8 assays for each of the 5 kits. The values varied with the kit used: serum 1: 2.6-3.95 μg/l in PR, SE, HE, but 1.9 and 1.99 in HY, PD, serum 2: 7.1-9.3 μg/l in PR, SE, ME but 3.9 and 5.5 in PD, HY, serum 3: 16.1-18.4 μg/l in PR, ME, SE but 8.6 and 11.6 in PD, HY. In addition, recovery of 5, 10, 20, 40 μg/l pituitary GH (received from the NIH, USA) added to serum was highly variable: it was high with PD(88.9-99.7%), ME(85.9-91.4%), SE(98.1-106.31), but markedly lower with PR(71.6-79.8%) and HY (55.8-65.4%). Data fron HY and SE, PD correlated significantly (r = 0.98-0.99, p<0.001).
In conclusion: The diversity of GB levels detenined with different assays emphasize the necessity of assay- adjusted normal ranges.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Stahnke, N., Jenke, I. COMPAIRING APPLES WITH PEARS. Pediatr Res 33 (Suppl 5), S68 (1993). https://doi.org/10.1203/00006450-199305001-00387
Issue Date:
DOI: https://doi.org/10.1203/00006450-199305001-00387