Leukotriene E₄-d₅(LTE₄-d₅) contains five deuterium atoms at the 19, 19', 20, 20 and 20 positions. It is intended for use as an internal standard for the quantification of LTE₄by GC-or LC-mass spectrometry. LTE₄is produced by the action of dipeptidase on LTD₄, leaving only the cysteinyl group still attached to the fatty acid backbone.¹It is one of the constituents of slow-reacting substance of anaphylaxis (SRS-A).²LTE₄is considerably less active (8 to 12-fold) than LTC₄in the biological activities characteristic of cysteinyl leukotrienes.^1,3Unlike LTC₄and LTD₄, LTE₄accumulates in both plasma and urine. Therefore, urinary excretion of LTE₄is most often used as an indicator of asthma.^4,5,6In humans, basal levels of LTE₄range from 1-100 pg/mg creatinine. In asthmatic patients, urinary LTE₄levels increase to 80-1,000 pg/mg creatinine.⁵

1.BernstrÖm, K., and HammarstrÖm, S.Metabolism of leukotriene D by porcine kidneyJ. Biol. Chem.256(18)9579-9582(1981) 2.Samuelsson, B.Leukotrienes: Mediators of immediate hypersensitivity reactions and inflammationScience220(4597)568-575(1983) 3.Lefer, A.M.Leukotrienes as mediators of ischemia and shockBiochem. Pharmacol.35(2)123-127(1986) 4.Kumlin, M., Stensvad, F., Larsson, L., et al.Validation and application of a new simple strategy for measurements of urinary leukotriene E4 in humansClin. Exp. Allergy25(5)467-479(1995) 5.Drazen, J.M., O'Brien, J., Sparrow, D., et al.Recovery of leukotriene E4 from the urine of patients with airway obstructionAm. Rev. Respir. Dis.146(1)104-108(1992) 6.Kumlin, M., DahlÉn, B., BjÖrck, T., et al.Urinary excretion of leukotriene E4 and 11-dehydro-thromboxane B2 in response to bronchial provocations with allergen, aspirin, leukotriene D4, and histamine in asthmaticsAm. Rev. Respir. Dis.146(1)96-103(1992)