title: Role of atrial natriuretic peptide in nocturnal polyuria in elderly males.
abstract: OBJECTIVE
  To demonstrate nocturnal polyuria objectively and to assess the role of atrial natriuretic peptide (ANP) in healthy elderly males with and without nocturnal polyuria (NP).
  
  
  METHODS
  31 healthy elderly men known to have NP (passing more than 33% of their 24-hour urine output during an 8-hour period overnight) and 12 controls without NP were invited to take part in the study. Blood and urine samples were collected at 4-hourly intervals in order to measure urine output, serum and urine electrolytes and osmolality as well as serum cortisol, renin, aldosterone, arginine vasopressin (AVP) and ANP.
  
  
  RESULTS
  26 men with NP and 8 controls agreed to take part in the study. Subjects with NP were found to have a diuresis and natriuresis as well as a significant increase in ANP overnight compared to the control group. There was no difference in the other parameters between the 3 groups, with the exception of aldosterone and AVP.
  
  
  CONCLUSIONS
  This study has shown a group of subjects with increased natriuresis and diuresis overnight, associated with an increase in ANP. It is possible that subclinical cardiac failure causes an increase in ANP therefore causing nocturnal urinary symptoms and this theory needs further exploration.
authors.affiliation: Bristol Urological Institute, Southmead Hospital, Bristol, UK.
authors.forename: P G
authors.initials: PG
authors.lastname: Carter
authors.forename: A
authors.initials: A
authors.lastname: Cannon
authors.forename: A A
authors.initials: AA
authors.lastname: McConnell
authors.forename: P
authors.initials: P
authors.lastname: Abrams
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000450:Aldosterone / Q000097:blood; D000704:Analysis of Variance; D009320:Atrial Natriuretic Factor / Q000032:analysis / Q000096:biosynthesis*; D015415:Biomarkers / Q000032:analysis; D002940:Circadian Rhythm; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008875:Middle Aged; D011141:Polyuria / Q000209:etiology / Q000503:physiopathology*; D011863:Radioimmunoassay; D012016:Reference Values; D012083:Renin / Q000097:blood; D016482:Urinalysis
chemical_list: D015415:Biomarkers; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012083:Renin; D006854:Hydrocortisone