Abstract
CicaFit AMY-G7 is a reagent kit that was designed as a transferable method proposed by the Japan Society of Clinical Chemistry (JSCC) for the measurement of amylase (AMY) using 4,6-ethylidene-4-nitrophenyl-α-D-maltoheptaoside (Et-G7-PNP) as a substrate. The values of AMY activity in patient serum and urine measured using CicaFit AMY-G7 were compared with those obtained by the Standard Operating Procedure for the measurement of the catalytic concentration of AMY established by the Japanese Committee for Clinical Laboratory Standards (JCCLS-SOP). The results obtained using CicaFit AMY-G7 were in good agreement with those determined by the JCCLS-SOP, regardless of variations in the proportion of pancreatic and salivary isoenzymes (P/T%) in each sample or sample type (serum or urine). For assays using α-2-chloro-4-nitrophenyl-β-D-galactopyranosylmaltoside (Gal-G2-CNP) and 2-chloro-4-nitrophenyl-α-D-maltotrioside (G3-CNP) as substrates, correlation analysis revealed a marked difference in the slopes of regression lines between serum and urine samples. Other kits employing the same substrate, namely, Et-G7-PNP, tended to give higher values for serum samples. The values of AMY activity in external quality assessment (EQA) samples measured using other kits differed from those obtained by the JCCLS-SOP when recombinant human AMY was added to the samples. Other kits using the Et-G7-PNP substrate gave slightly higher values and those using the G3-CNP substrate provided slightly lower values (within ± 5% of the target value for both), while those using the Gal-G2-CNP substrate gave values that were below the permissible lower limit.
