1,2-Dioleoylglycerol method for pancreatic lipase catalytic activity in serum.

BACKGROUND: There is a need for a pancreatic lipase (LIP) reference assay to provide an accurate base to which routine methods can be traceable. METHODS: This study developed a novel LIP assay method in which 1,2-dioleoylglycerol (DODG) is the substrate and LIP activity is measured in a coupled enzymatic reaction from the increase in absorbance at 340 nm with production of NADPH. RESULTS: With this method, LIP activity was linear up to 440 U/L (8-times expected upper limit of physiological concentration). When assayed manually, the between-laboratory variation for six samples surveyed at five laboratories was 3.80-26.4% (CV) for samples containing about 20-290 U/L LIP activity; when assayed using an automated analyzer, the range was 1.86-4.86% (four laboratories). Interference by >5 mmol/L glycerol and low specificity with post-heparin samples were noted, but in practice these are avoidable. Precision analyzed by automated assay of 49 samples twice in random order produced a covariance of 2.27 U/L, which is comparable to routine methods, and good correlations were obtained with five routine methods. CONCLUSIONS: Although further studies are required, the DODG method may be likely applicable as one candidate reference method.

[Age specific reference ranges and clinical trial for complexed prostate specific antigen (cPSA)].

We compared the complexed PSA (cPSA) reference range of values by age against that for total PSA. The subjects were 1,210 men who underwent a complete medical checkup at our center between September and November 2003. We found an upward trend of the measured values associated with age and defined a set of expected result range by age groups. The cPSA 95th percentile upper limit value increased across all age groups: for men under 40 years, 1.38ng/ml: for men 40 to 49 years, 1.60ng/ml; for men 50 to 59 years, 2.25 ng/ml; for men 60 to 69 years, 2.50 ng/ml; and for men 70 years older, 4.31 ng/ml (The number of subjects in each group was 153, 323, 429, 220 and 77). The total PSA also increased with age: 1.85 ng/ml, 2.11 ng/ml, 2.80 ng/ml, 4.20 ng/ml, and 5.69 ng/ml, respectively. We also compared other prostatic tumor markers in urology patients.