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We have developed a method for measuring leukotriene B4 glucuronide, a marker of systemic leukotriene B4 biosynthesis, in human urine. This method involves the separation of two positional isomers of leukotriene B4 glucuronide by high-performance liquid chromatography, followed by hydrolysis with beta-glucuronidase and then leukotriene B4 quantification by enzyme immunoassay after purification by high-performance liquid chromatography. One of two positional isomers of leukotriene B4 glucuronide was predominantly present in urine. The concentration of the isomer increased in urine from aspirin-intolerant asthma patients after aspirin challenge. Urinary leukotriene E4 and leukotriene B4 glucuronide concentrations in 13 normal healthy adults were 94.6 pg/mg-creatinine (median) and 22.3 pg/mg-creatinine, respectively. Urinary LTE4 concentration increased during the first 3h after allergen inhalation in atopic patients. However, allergen-induced bronchoconstriction was not associated with an increased concentration of LTB4 glucuronide in urine. The method enabled us to precisely determine urinary leukotriene B4 glucuronide concentration.

Five milligrams of [5,6,8,9,11,12,14,15-3H8]-leukotriene B4 (LTB4) (1.68 Ci/mmol) were infused into a monkey over a three hour period. Twenty-five per cent of the infused 3H-activity was recovered in the urine during the twenty hours of collection. Plasma and urinary metabolite volatility studies revealed that in contrast to previously studied eicosanoids, more than 70% per cent of the infused LTB4 3H-label was converted to tritiated water. The major nonvolatile urinary metabolite of LTB4 representing 0.8% of the infused material was identified as 20-OH-LTB4. LTB4 was not excreted in the urine. Other nonvolatile metabolites of LTB4 representing less than 0.4% each of the infused material were isolated from the urine. While there was an adequate quantity of some of these metabolites for partial characterization, there was insufficient material for structural elucidation. Further studies were performed in rabbits in which either LTB4 or the structurally related compound 8,15-dihydroxyeicosatetraenoic acid (8,15-diHETE) were infused intravenously. In these rabbits the metabolism of LTB4 and 8,15-diHETE was similar to that in the monkey with greater than 80% of the infused 3H-activity converted to tritiated water. These studies suggest that leukotriene B4 and structurally related compounds undergo extensive degradation in vivo via the beta-oxidation system.