Development and evaluation of assays for the determination of total and pancreatic amylase at 37 degrees C according to the principle recommended by the IFCC.
OBJECTIVE
The aim of our study was a) to optimize assays for measurement of total (T-) and pancreatic (P-)amylase at 37 degrees C based on the principle recommended by the IFCC at 30 degrees C, b) to evaluate the analytical performance of these assays in a multicentric study and c) to establish reference intervals for serum and urine for either method.


METHODS
Optimized conditions for 37 degrees C were elaborated with regard to substrate concentration, pH, inorganic additives and glucosidase activity. The cleavage pattern of the EPS substrate was studied by HPLC. Liquid ready-to-use reagents for T- and P-amylase were provided to six European laboratories.


RESULTS
The assays showed good performance characteristics (median intraassay CVs 1.0% for T- and 1.3% for P-amylase, median interassay CVs 3.0% for either assay, dynamic range 15-fold URL for T- and 30-fold for P-amylase), high correlation with the previous EPS methods (r > 0.996, slope 0.43, intercept < 5 U/L) in serum, heparin plasma and urine and good analytical specificity of the P-amylase assay (residual S-amylase activity 2.4%). Serum reference ranges were found to be 28 to 100 U/L for T- and 13 to 53 U/L for P-amylase (n = 775); URLs in urine were estimated as 490 U/L or 280 U/g creatinine for males and 450 U/L or 380 U/g creatinine for females with total amylase.


CONCLUSIONS
We believe that these assays based on the 30 degrees C IFCC recommendation represent a further improvement in amylase methodology at 37 degrees C and merit broad application in clinical routine.
Junge
W
W
Zentrallaboratorium, Friedrich-Ebert-Krankenhaus, Neumuenster, Germany. LKF_Junge@t-online.de
Wortmann
W
W
Wilke
B
B
Waldenström
J
J
Kurrle-Weittenhiller
A
A
Finke
J
J
Klein
G
G
D000681:Amylases / Q000097:blood / Q000378:metabolism* / Q000652:urine; D005960:Glucosides / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D010179:Pancreas / Q000201:enzymology*; D012016:Reference Values; D012680:Sensitivity and Specificity; D013696:Temperature; D000520:alpha-Glucosidases / Q000378:metabolism*
D005960:Glucosides; D007527:Isoenzymes; C036167:4-nitrophenyl maltoheptaoside; D000681:Amylases; D000520:alpha-Glucosidases