Study on Reference Values of PGE Major Metabolite in Urine (PGE-MUM) Measured by Simple RIA Kit: Population Base Study in Tokyo

Abstract

Ulcerative colitis (UC) is a problematic stage of IBD and requires colonoscopic determination for confirmatory diagnosis and after therapeutic intervention, which is burdensome to patients. Noninvasive method to reflect the inflammatory conditions is highly desirable. COX is a key enzyme to produce prostaglandin E2 as a major inflammatory product in UC. However the half-life of PG E2 is very short to measure. Urinary PG E2 metabolite (PGE-MUM) is a candidate to measure as an equivalent of PG E2 in body. We have shown preliminary data of PGE-MUM in UC utilizing an immunologic assay method previously. Although an LC-MS method is reported to measure the level of PGE-MUM, a simple method as kit level is preferable. Reference value of healthy subjects is not yet available. We recruited 797 subjects at Japanese Red Cross Medical Center. Pretreatment of urine sample with base, then neutralized, is provided to the radioimmunoassay (Bicyclic PGE-MUM RIA kit, TFB, Japan), where the specific antibodies against stable bicyclic PGE metabolite derivative are utilized. Correction with urinary creatinine (Cr) concentration was carried out. Comparison with CRP value is also carried out. The values in men were higher than those in women. The results are comparable to the data by LC-MS. The level gradually decreased with age in men (median, ∼40, 41∼60, ∼61 years = 15.2, 14.2, 11.7 ng/g Cr), and was opposite in women (median, 8.6, 9.3, 10.9 ng/g Cr). PGE-MUM level varied during working time (morning to evening), especially in hard workers, reflecting stress effect. The value for current smokers were higher than for former smokers or nonsmokers. The PEG-MUM level is higher in men than women, especially men who smoke. Age factor may be integrated or considered for reference value.