Reference ranges for alpha-amylase in serum and urine with 4,6-ethylidene-(G7)-1-4-nitrophenyl-(G1)-alpha,D-maltoheptaoside as substrate.

Reference ranges for alpha-amylase in serum, spontaneously voided urine, and 24 h urine were determined, using 4,6-ethylidene-(G7)-1-4-nitrophenyl-(Gl)-alpha,D-maltoheptaoside as the substrate (EPS method), at 25, 30, and 37 degrees C. The measured values were evaluated with and without the use of a factor which converts the results of the alpha-amylase EPS method into values comparable to those obtained with the alpha-amylase PNP method (substrate: 4-nitrophenyl-alpha,D-maltoheptaoside); comparison with the established reference ranges of the PNP method was therefore possible. The values for urine sometimes deviated markedly from the PNP reference ranges, but the values for serum showed close agreement. With the use of the conversion factor, the following reference ranges are proposed for the new alpha-amylase method: Serum (186 males and 131 females): up to 120 U/l (25 degrees C), up to 160 U/l (30 degrees C), and up to 220 U/l (37 degrees C). Spontaneously voided urine: up to 600 U/l (n = 323, 25 degrees C), up to 800 U/l (n = 373, 30 degrees C), and up to 1000 U/l (n = 373, 37 degrees C). 24 h urine: up to 450 U/24 h (n = 90, 25 degrees C), up to 650 U/24 h (n = 129, 30 degrees C), and up to 900 U/24 h (n = 129, 37 degrees C).