Abstract
A validation study of three different PTH measuring kits (C-PTH, HS-PTH, and AI-PTH) was conducted on patients with chronic renal insufficiency undergoing hemodialysis, and yielded the following results.
(1) Satisfactory response curves for all three types of PTH were obtained from the detection curves determined by using standard sera. Detection sensitivity was 0.3-0.4ng/ml for C-PTH, about 120pg/ml for HS-PTH, and 2pg/ml for AI-PTH. (2) The coefficients of variation for intra-assay (simultaneous reproducibility) and inter-assay (reproducibility between measurements) in the hemodialysis patients were 4.4% and 3.9% (C-PTH), 4.5% and 7.0% (HS-PTH), and 3.4% and 8.5% (AI-PTH), respectively. These data show good precision and reproducibility with these 3 PTH assays in serum from hemodialysed patients. (3) When the influence of standing time of whole blood after sampling on stability was investigated, the measuring values were as follows: for C-PTH, stable from 15min to 24hr; for HS-PTH, stable from 15min to 8hr, but with a significant drop after 24hr; and for AI-PTH, stable from 30min to 2hr with few variations, but with slightly higher values obtained after 15min, and with a significant drop after 4hr. These results suggest that serum be separated from 15min to 24hr after sampling for C-PTH, from 15min to 8hr for HS-PTH, and from 30min to 2hr for AI-PTH to obtain reliable PTH values in hemodialysed patients. (4) The coefficient of variation for weekly differences in patients managed under the same conditions was 8.1% for C-PTH, 9.7% for HS-PTH, and 20.7% for AI-PTH.
