Introduction

Congestive heart failure (CHF) has been assumed to be one of the causes of nocturia. The relationship between nocturia and the extent of cardiac load, however, has not been fully examined. Brain-type natriuretic peptide (BNP) is a diuretic and vasodilatory hormone that is secreted in response to the left ventricular load and reported to be associated with the severity of CHF. Moreover, BNP can reflect the cardiac load before cardiac symptoms develop (Adnan Nadir et al., J Am Coll Cardiol HF 2015). In this study, we aimed to investigate the influence of the cardiac load evaluated by BNP on nocturia.

Methods

This retrospective study included 431 men whose BNP levels were evaluated before prostate biopsy between 2014 and 2016. We assessed the frequency of nocturnal voiding by International Prostate Symptom Score (IPSS). Nocturia was defined as voiding at night two or more times. The association of BNP and other clinical variables with nocturia was examined using multivariate logistic regression analyses. The other variables were age, prostate-specific antigen (PSA), prostate volume, body mass index, the presence of prostate cancer, estimated glomerular ?ltration rate (eGFR), hypertension, diabetes, sleep disorder, and the use of any ?-blocker or muscarinic antagonist. We also assessed the correlation between BNP and each item in the IPSS subgroups.

Results

Median age, BNP, and PSA were 69 years, 19.8 pg/ml and 8.7 ng/ml, respectively. Median time of nocturnal voiding was 1 and nocturia was observed in 191 men (44.3%). Presence or absence of prostate cancer was not associated with nocturia or BNP levels. Median BNP in men with nocturia was 26.5 pg/ml whereas that in men without nocturia was 13.7 pg/ml (p < 0.01). Median BNP in each frequency group of nocturnal voiding was 13.1 ng/ml in 0 times (n = 65), 14.2 ng/ml in 1 time (n = 175), 23.9 ng/ml in 2 times (n = 118), 37.1 ng/ml in 3 times (n = 52), and 37.9 ng/ml in 4 or more times (n = 21) (p < 0.01). Univariate analyses demonstrated that age, PSA, prostate volume, eGFR, use of any ?-blocker, hypertension, diabetes, sleep disorder, and BNP were correlated with nocturia. In multivariate analyses, BNP (p < 0.01) was an independent risk factor of nocturia, as well as age (p < 0.01), prostate volume (p < 0.01), and diabetes (p = 0.04). There were no correlations between BNP and each item in the IPSS subgroups other than nocturia.

Conclusions

BNP, a representative biomarker for cardiac load, is associated with nocturia in men.

Funding

none