Soluble interleukin 6 receptor: A novel marker of moderate to severe sleep-related breathing disorder

Arch Intern Med. 2006 Sep 18;166(16):1725-31. doi: 10.1001/archinte.166.16.1725.


Background: Given the previously described association between sleep-related breathing disorder (SRBD) and markers of inflammation, we assessed the relationship of SRBD with levels of both interleukin 6 (IL-6) and soluble IL-6 receptor (sIL-6R), a marker with more expansive physiologic effects than IL-6. The objectives were to explore the relationship between moderate to severe sleep apnea with IL-6 and sIL-6R levels and to examine morning and evening variability for each cytokine.

Methods: A total of 385 adult participants (> or =18 years of age) in the Cleveland Family Study, Cleveland, Ohio, underwent sleep studies and determination of IL-6 and sIL-6R levels in samples obtained in the evening and morning of polysomnography. Moderate to severe SRBD was defined as a respiratory disturbance index greater than or equal to 30.

Results: The subjects were aged 44.9 +/- 16.7 (mean +/- SD) years, 44% were male, and 48% were African American, with a body mass index (weight in kilograms divided by the height in meters squared) of 32.5 +/- 8.1 (mean +/- SD). Linear regression analysis showed that after adjustment for subject characteristics, waist circumference, and comorbidities, SRBD was not significantly associated with morning IL-6 levels. In contrast, linear regression analyses showed that, compared with the participants without SRBD, those with SRBD had significantly higher morning sIL-6R levels (mean +/- SD, 4.60 +/- 1.42 ng/mL [P = .001]), even after adjustment for subject characteristics, waist circumference, and comorbidities, which persisted after adjustment of evening sIL-6R levels.

Conclusions: Morning sIL-6R levels demonstrated stronger associations with moderate to severe SRBD than morning IL-6 levels. Associations with SRBD and morning sIL-6R levels persisted even after adjustment for waist circumference, cardiovascular disease, and evening sIL-6R levels, suggesting the potential utility of sIL-6R as a marker for measuring overnight SRBD stresses. Further investigation of this biomarker may provide insight into SRBD-related inflammation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers / blood
  • Body Mass Index
  • Female
  • Humans
  • Interleukin-6 / blood*
  • Linear Models
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Polysomnography
  • Receptors, Interleukin-6 / blood*
  • Severity of Illness Index*
  • Sleep Apnea Syndromes / blood*
  • Time Factors
  • Waist-Hip Ratio


  • Biomarkers
  • Interleukin-6
  • Receptors, Interleukin-6