Urinary leukotriene E(4) levels in high-altitude pulmonary edema - A possible role for inflammation

Study objectives: 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 E(4) (LTE(4)), is elevated in patients with HAPE. Design: We conducted a case-control study to collect clinical data and urine samples from HAPE patients and healthy control subjects at moderate altitude (greater than or equal to 2727 m), and follow-up urine samples from HAPE patients following their return to low altitude (less than or equal to 1,600 m). Setting: Five medical clinics in Summit County, Colorado. Patients: Questionnaire data were evaluated in 71 HAPE patients and 36 control subjects, Urinary LTE(4) 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. Measurements ana results: Using an enzyme immunoassay technique, urinary LTE(4) 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 LTE(4) levels fell significantly from 122 (41.8 to 309) to 53.6 (27.6 to 104) pg/mg creatinine (p=0.05). Urinary LTE(4) 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 NSAIDs. Conclusions: We conclude that urinary LTE(4) levels are elevated in patients with HAPE, supporting the view that HAPE involves inflammatory mechanisms.