A urine biomarker for severe obstructive sleep apnoea patients: Lipocalin-type prostaglandin D synthase

Abstract

Lipocalin-type prostaglandin D synthase (L-PGDS), which is responsible for the biosynthesis of prostaglandin D2, has been reported to have a close connection with cardiovascular disease and sleep regulation. This study aimed to test the hypothesis that the L-PGDS level is a useful marker to identify patients with obstructive sleep apnoea. 64 subjects were enrolled in this prospective study. Urinary concentrations of L-PGDS were measured in the morning. Measurements were made every 4 h in 25 of the 64 patients. Endothelial function was assessed by the reactive hyperaemia peripheral arterial tone index. Circadian variations in L-PGDS concentrations had a significant time-dependent fluctuation (p=0.0002). L-PGDS was higher in the subjects with severe obstructive sleep apnoea (median 784.7 ng per mg of creatinine, n=23) than in control subjects (262.1 ng per mg of creatinine, n=16; p=0.004) and in those with moderate obstructive sleep apnoea (371.7 ng per mg of creatinine, n=25; p=0.0008). After 2 days of continuous positive airway pressure treatment, L-PGDS concentrations in severe obstructive sleep apnoea subjects (n=12) decreased significantly (p=0.02) to levels present in control subjects whereas endothelial function did not change significantly. Morning urinary L-PGDS concentrations had significant correlations with the apnoea/hypopnoea index (R 2=13.9%) and serum high-density lipoprotein cholesterol (R 2=6.2%), but not with sleepiness. Urinary L-PGDS might be a moderately useful marker to identify patients with severe obstructive sleep apnoea. Copyright © ERS 2013.