Human atrial natriuretic peptide is a useful criterion in treatment of nocturia

Nocturia is one of the major problems of elderly people. The possible causes of nocturia include irritation of lower urinary tract obstruction, disturbance of the fluid balance, and sleep disturbance. In a significant proportion of patients, the mechanism of nocturia is still unclear and a definitive method of treatment has yet to be determined. This study investigated how to treat nocturia.

We analyzed 51 patients who visited Kobe City General Hospital between January 1998 and June 1999 with nocturia (three or more nocturnal voidings) and no daytime urological problems. Twenty-two of these patients were given daytime diuretic therapy (azosemide 60 mg), while 29 other patients received a minor tranquilizer. The method of treatment was selected randomly. Correlations between the plasma level of atrial natriuretic peptide (hANP) and the effect of treatment were analyzed.

Daytime diuretics decreased the nocturnal frequency of voiding in 10 out of 22 patients. The plasma hANP level at the first visit was significantly higher in the patients with improvement (p = 0.0026). Furthermore, the plasma hANP level was significantly decreased after daytime diuretic therapy in patients who showed improvement of nocturia with diuretic therapy (p = 0.0180). Minor tranquilizer administration decreased nocturia in 22 out of 29 patients. The plasma hANP level at the first visit was significantly lower in the patients who improved (p = 0.0021).

These findings suggest that patients with higher plasma hANP levels should be treated as having subclinical heart failure, while nocturia in patients with a normal plasma hANP level might be caused by sleep disturbance.