title: Influence of age, posture and intra-individual variation on plasma levels of atrial natriuretic peptide.
abstract: This paper describes some factors to which attention should be paid when atrial natriuretic peptide (ANP) values are to be interpreted. Changing from the supine to the sitting position decreased ANP levels, while no further decrease was observed when the upright position was assumed. On the other hand, plasma renin activity (PRA) increased only when changing from the sitting to the upright position. Returning to the supine position decreased PRA, while ANP did not change. Under these conditions plasma aldosterone levels did not differ in any of the four positions. No correlation was observed between the percentage changes of ANP, PRA and aldosterone. ANP values measured in 66 healthy subjects positively correlated with age (r = 0.59, P less than 0.01). To study intra-individual variation, ANP was sampled eight times within one hour. The mean, standard deviation and the coefficient of variation (CV) for each subject were calculated. The CV of 9 out of 15 subjects significantly exceeded the intra-assay coefficient of variation (7.0%), thereby indicating that ANP levels, like those of many other hormones, may exhibit endogenous fluctuations.
authors.affiliation: Department of Experimental and Chemical Endocrinology, St Radboud Hospital, University of Nijmegen, The Netherlands.
authors.forename: A C
authors.initials: AC
authors.lastname: Tan
authors.forename: P W
authors.initials: PW
authors.lastname: Kloppenborg
authors.forename: T J
authors.initials: TJ
authors.lastname: Benraad
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000450:Aldosterone / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood*; D005260:Female; D006801:Humans; D007206:Individuality; D008297:Male; D008875:Middle Aged; D011187:Posture; D012083:Renin / Q000097:blood
chemical_list: D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012083:Renin