Problematic determination of serum growth hormone: experience from external quality assurance surveys 1998-2003.
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.
Mörsky
P
P
Centre for Laboratory Medicine, Pirkanmaa Hospital District, Tampere, Finland. pertti.morsky@pshp.fi
Tiikkainen
U
U
Ruokonen
A
A
Markkanen
H
H
D001774:Blood Chemical Analysis / Q000592:standards; D002138:Calibration; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D011785:Quality Assurance, Health Care
D019382:Human Growth Hormone