title: Night and day proteinuria in patients with sleep apnea.
abstract: BACKGROUND
  Previous studies have suggested an association between obstructive sleep apnea (OSA) and heavy proteinuria. Two recent studies cast doubt on the association between OSA and proteinuria, but neither studied the effect of disordered sleep per se on urinary protein excretion.
  
  
  METHODS
  We prospectively studied 75 patients undergoing polysomnography for suspected OSA. We excluded patients with renal insufficiency, diabetes mellitus, and systemic lupus erythematosus and those administered angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Urine protein-creatinine (P/C) ratio was measured on the date of the polysomnography before sleep (awake P/C ratio) and on awakening (asleep P/C ratio). Severity of OSA was stratified by means of the apnea-hypopnea index (AHI).
  
  
  RESULTS
  Twenty-six patients (35%) did not have OSA, 25 patients (33%) had mild OSA, 9 patients (12%) had moderate OSA, and 15 patients (20%) had severe OSA. Asleep P/C ratio was less than 0.2 in 96% of patients, and awake P/C ratio was less than 0.2 in 89% of patients. No patient had an asleep P/C ratio greater than 1.0. There was no correlation between log asleep P/C ratio and log AHI ( r = -0.042; P = 0.73) or log awake P/C ratio and log AHI (r = 0.004; P = 0.97). No significant differences could be shown between mean log P/C ratio for either the asleep or awake urine collection across any of the 4 OSA severity strata.
  
  
  CONCLUSIONS
  We found clinically significant proteinuria to be absent in stable outpatients with OSA. Proteinuria in patients with OSA should not be attributed to sleep apnea and warrants further evaluation.
authors.affiliation: Critical Care Unit, Hospital Terapia Intensiva, Universidade Estadual Piaui, Teresina, Piaui, Brazil.
authors.forename: Patricia
authors.initials: P
authors.lastname: Mello
authors.forename: Margaret
authors.initials: M
authors.lastname: Franger
authors.forename: Ziad
authors.initials: Z
authors.lastname: Boujaoude
authors.forename: Mark
authors.initials: M
authors.lastname: Adaimy
authors.forename: Elena
authors.initials: E
authors.lastname: Gelfand
authors.forename: Jonathan
authors.initials: J
authors.lastname: Kass
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Weisberg
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D011507:Proteinuria / Q000150:complications*; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000503:physiopathology