Increased cardiac troponin T and C-reactive protein levels in end-stage renal disease are associated with obstructive sleep apnea.

BACKGROUND

Increased cardiac troponin T (cTnT) and C-reactive protein (CRP) levels predict mortality in patients with end-stage renal disease (ESRD) on maintenance hemodialysis. Obstructive sleep apnea (OSA) is associated with severe cardiac stress and systemic inflammation. We hypothesized that in patients with ESRD elevated levels of cTnT and CRP are consequences of unrecognized OSA.

METHODS

After diagnostic polysomnography, serum levels of cTnT and CRP were assessed in two groups of patients. The first group with normal renal function which served as a control group, was recruited from routine patient referrals to the sleep laboratory at the University Hospital Magdeburg. The second group consisted of patients with ESRD on thrice-weekly maintenance hemodialysis treatment (hemodialysis group).

RESULTS

After screening, 15 patients in each group were eligible for inclusion. OSA (apnea hypopnea index (AHI) > or = 10) was associated with significantly elevated serum CRP levels of 5.1 +/- 4.9 mg/l in the control group and 11.6 +/- 10.2 mg/l in the hemodialysis group, compared with patients in the respective groups without OSA. In the control group, cTnT levels were below the lower detection limit, independent of OSA severity. Patients with ESRD but without OSA had low cTnT levels, similar to those of patients in the control group (0.014 +/- 0.01 ìg/l), whereas patients with ESRD and OSA had significantly elevated serum cTnT levels (0.38 +/- 0.3 microg/l, p < 0.05).

CONCLUSIONS

OSA is associated with higher CRP levels in patients with normal or impaired renal function, but cTnT is elevated in OSA patients with impaired renal function only. In this pilot study, both parameters suggest an important role of sleep related breathing disorders on cardiac stress and chronic inflammation.