CIRCADIAN ANTIDIURETIC-HORMONE VARIATION IN ELDERLY MEN COMPLAINING OF PERSISTENT NOCTURIA AFTER URINARY FLOW OBSTRUCTION REMOVAL

Persistence of nocturia after prostatic resection in healthy patients without symptoms referred to residual bladder instability and to patho logical polyuria seems to be caused by an increased urine production a t night. The more accreditate mechanism involved is the relevant decre ased ADH secretion pattern which occurs at night. In our study, patien ts with nocturnal poliuria showed significantly low plasmatic vasopres sin levels compared with a control group. The aim of this study was to evaluate whether the persistence of nocturia after prostatic resectio n in healthy patients, without symptoms referred due to residual bladd er instability and important polyuria, could be due to a decrease or a lack of increase in antidiuretic hormone (ADH) nocturnal levels follo wing increased urine production at night. Serum ADH, atrial natriureti c peptide (ANP) and osmolality were assessed at 4-h intervals in 12 pa tients complaining of residual nocturia (group A) and in a control gro up of 13 patients who had undergone a complete resolution of nocturia after prostate ablation (group B). In the 25 patients involved in the study (mean age 65.8 years), no significant differences were observed in the two groups concerning mean age (67.5 years for group A, 64 year s for group B). Mean nocturnal urine volume (1080 +/- 490 ml) in group A patients was significantly higher than in group B (500 +/- 100 ml) (p < 0.001), while no significant differences were found in diurnal di uresis. Mean plasma vasopressin levels of the 12 patients showing an i ncreased nocturnal micturition were found to be significantly lower at all 4-h intervals when compared with the control group (p < 0.05). In dividual fluctuations in serum osmolality were slight and insignifican t within the normal range in all patients. The diurnal variation of pl asma atrial natriuretic peptide was within the reference limits for al l subjects during the 24-h period. Our results lead us to believe that residual nocturia after prostatic resection seems to be caused by an increased urine production at: night due to a decreased ADH secretion pattern.