Altered Water Excretion In

Abstract

The renal and vasopressin (AVP) response to a standard oral water load (20 ml/kg) was examined in a group of water-replete healthy elderly men (n = 6). Two groups, respectively, of water-replete and water-deprived young healthy volunteers acted as controls. After 2 h, the old group had excreted 41 +/- 2.4% (mean +/- SEM) of the water load compared to 100.7 +/- 8.8% in the water-replete young group and 70 +/- 3.8% in the water-deprived young group (P less than 0.01). Similarly, peak diuresis (7.01 +/- 0.48 ml/kg) and peak free-water clearance (5.7 +/- 0.48 ml/min) as determined from hourly sampling in the old group were delayed and significantly less than both young groups (P less than 0.01) (peak diuresis, young water-replete, 10.86 +/- 0.56 ml/kg, young water-deprived, 10.2 +/- 0.64 ml/kg, peak free-water clearance, young water-replete 8.4 +/- 0.72 ml/min, young water-deprived 9.5 +/- 0.88 ml/min). When these indices were adjusted for reduced creatinine clearance (Ccr) in the elderly, there was no significant difference between the young and old groups. Plasma AVP decreased similarly in all three groups following ingestion of water but there was no significant difference in mean plasma AVP between the young and old subjects throughout the study period. We therefore conclude that ability to excrete excess water promptly is impaired in healthy elderly men. This defect is due, at least in part, to an age-related reduction in glomerular filtration rate.

Age‐related changes in pharmacokinetics and pharmacodynamics: basic principles and practical applications

“…Basal vasopressin secretion is probably normal in elderly subjects. However, both normal and reduced responses to water deprivation have been described [18,19]. Although the ability to conserve salt is maintained, there is a delay in balancing losses [20].…”

Validation of a dietary record routine in geriatric patients using doubly labelled water

“…This population is at risk for dehydration because the elderly have a diminished sensation of thirst and are less able to regulate their¯uid balance (Crowe et al, 1987;Phillips et al, 1991). If left untreated, dehydration can result in death in many cases (Mahowald & Himmelstein, 1981;Warren et al, 1994).…”

Elderly Female Patients in Continuing Care: Why Are They Hyperosmolar?

“…It has been suggested that hypodipsia and consequent dehydration may be a major problem for elderly people in long-term care [1], In the fit elderly Philips et al [2] re ported that thirst was reduced and it is known that water conservation is impaired in ageing [2][3][4], We have previously pre sented a preliminary survey which showed that only 7 out of 58 long-stay residents had an osmolality of less than 296 mosm/kg [5], The reasons for the hyperosmolar state were not clear but it was possibly linked to chronic confusion. No attempt was made to measure the fluid input.…”