Urinary Leukotriene E4 Levels in High-Altitude Pulmonary Edema: A Possible Role for Inflammation

Abstract

<h3>Study objectives</h3> Inflammation may contribute to the pathogenesis of high-altitude pulmonary edema (HAPE). This study was designed to determine whether a marker of inflammation, urinary leukotriene E4 (LTE4), is elevated in patients with HAPE. <h3>Design</h3> We conducted a case-control study to collect clinical data and urine samples from HAPE patients and healthy control subjects at moderate altitude (≥2727 m), and follow-up urine samples from HAPE patients following their return to low altitude (≤1,600 m). <h3>Setting</h3> Five medical clinics in Summit County, Colorado. <h3>Patients</h3> Questionnaire data were evaluated in 71 HAPE patients and 36 control subjects. Urinary LTE4 levels were determined from a random subset of 38 HAPE patients and 10 control subjects presenting at moderate altitude, and on 5 HAPE patients who had returned to low altitude. <h3>Measurements and Results</h3> Using an enzyme immunoassay technique, urinary LTE4 levels were found to be significantly higher in HAPE patients (123 [16 to 468] pg/mg creatinine, geometric mean [range]) than in control subjects (69 [38 to 135]), p=0.02. Following return to low altitude, urinary LTE4 levels fell significantly from 122 (41.8 to 309) to 53.6 (27.6 to 104) pg/mg creatinine (p=0.05). Urinary LTE4 levels were not related to age, sex, time at altitude, physical condition or habitual exercise, recent use of alcohol or nonsteroidal anti-inflammatory drugs (NSAIDs), or oxygen saturation. Clinical factors associated with HAPE included male sex, regular exercise, and recent use of NSAIDs. <h3>Conclusions</h3> We conclude that urinary LTE4 levels are elevated in patients with HAPE, supporting the view that HAPE involves inflammatory mechanisms.