Introduction: Nocturia (two or more urinations per night) is a common symptom in OSA subjects. Higher secretion of atrial natriuretic peptide, increased intra-abdominal pressure, diuretics, diabetes, excessive fluid intake, awakenings are responsible for nocturnal urination. The aim of this study was to evaluate incidence of nocturia in moderate and severe OSA.
Material and methods: We studied 171 consecutive OSA patients (135 males and 36 females) - means: age - 53.6 +/- +/- 10.8 years, AHI/RDI - 43.6 +/- 23.2, BMI - 35.8 +/- 6.3 kg/m(2).
Results: To assess relations between nocturia and AHI/RDI, overnight saturation, BMI and daytime sleepiness we divided subjects in two groups: 1(st) - without nocturia - 60 pts; 35.1% (group N-) and 2(nd) - with nocturia - 111 pts; 64.9% (group N+). Group N+ presented with higher AHI/RDI, 48 +/- 22.8 vs. 35.4 +/- 21.7 (p = 0.0006), higher BMI, 36.8 +/- 6.5 vs. 34 +/- 5.5 kg/m(2) (p = 0.004), lower mean overnight SaO(2), 88.6 +/- 5.6 vs. 90.4 +/- 4.3% (p = 0.03) and daytime sleepiness, Epworth score - 14.4 +/- 5.1 vs. 11.3 +/- 5.5 points (p = 0.0002). Multiple linear regression analysis revealed significant correlation between nocturia and Epworth sleepiness score (beta = 0.26, p = 0.0009), coronary artery disease (beta = 0.23, p = 0.004) and AHI/RDI (beta = 0.21, p = 0.04).
Conclusions: Nocturia is frequent in OSA patients (64.9%). Nocturnal urination was related to severity of OSA, excessive daytime sleepiness and coronary artery disease.