Level of hydration and renal function in healthy humans

Anastasio, P; Cirillo, Massimo; Spitali, L; Frangiosa, A; Pollastro, Rosa Maria; Santo, Natale G. De

doi:10.1046/j.1523-1755.2001.060002748.x

Cited by 91 publications

(77 citation statements)

References 12 publications

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“…In two small studies of acute water loading in healthy adults, a transient increase in albumin excretion was observed in one (27), and the other showed that the effect of fluid loading on GFR was dependent on whether participants had consumed a high-protein meal or were in a fasting state (28). Anastasio et al underlined the acute nature of these experiments, which cannot be generalized to the effects of chronic high hydration (28). We previously noted an association between polyuria and 24-hour urine protein, but a subsequent investigation revealed that laboratory measurement error was the most likely explanation for these results (13,29).…”

Section: Discussionmentioning

confidence: 98%

“…Kidneys may function more efficiently in the presence of an abundant supply of water (33). Higher fluid intake increases the clearance of sodium, urea, and osmoles (4,28,34), and high fluid intake is the most effective therapeutic measure to prevent kidney stones (6,7,35). If the kidneys are made to economize on water and produce more concentrated urine to maintain plasma osmolality, they may incur greater metabolic demand, as demonstrated in studies of rats (23,32,36,37).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Urine Volume and Change in Estimated GFR in a Community-Based Cohort Study

Clark

Sontrop

Macnab

et al. 2011

Clinical Journal of the American Society of Nephrology

161

146

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SummaryBackground and objectives The effect of increased fluid intake on kidney function is unclear. This study evaluates the relationship between urine volume and renal decline over 6 years in a large community-based cohort.Design, setting, participants, & measurements This prospective cohort study was undertaken in Canada from 2002 to 2008. We obtained 24-hour urine samples from adult participants with an estimated GFR (eGFR) Ն60ml/min per 1.73 m 2 at study entry. Percentage annual change in eGFR from baseline was categorized as average decline Ͻ1% per year, between 1% and 4.9% (mild-to-moderate decline) or Ն5% (rapid decline).Results 2148 participants provided valid 24-hour urine samples, grouped as Ͻ1 L/d (14.5%); 1 to 1.9 L/d (51.5%); 2 to 2.9 L/d (26.3%); and Ն3 L/d (7.7%). Baseline eGFR for each category of urine volume was 90, 88, 84, and 87 ml/min per 1.73 m 2 , respectively. Overall, eGFR declined by 1% per year, with 10% demonstrating rapid decline and 40% demonstrating mild-to-moderate decline. An inverse, graded relationship was evident between urine volume and eGFR decline: For each increasing category of 24-hour urine volume, percentage annual eGFR decline was progressively slower, from 1.3%, 1.0%, 0.8%, to 0.5%, respectively; P ϭ 0.02. Compared with those with urine volume 1 to 1.9 L/d, those with urine volume Ն3 L/d were significantly less likely to demonstrate mild-to-moderate decline (adjusted odds ratio 0.66; 95% confidence interval 0.46 to 0.94) or rapid decline (adjusted odds ratio 0.46; 95% confidence interval 0.23 to 0.92); adjusted for age, gender, baseline eGFR, medication use for hypertension (including diuretics), proteinuria, diabetes, and cardiovascular disease. ConclusionsIn this community-based cohort, decline in kidney function was significantly slower in those with higher versus lower urine volume.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Urine Volume and Change in Estimated GFR in a Community-Based Cohort Study

Clark

Sontrop

Macnab

et al. 2011

Clinical Journal of the American Society of Nephrology

161

146

View full text Add to dashboard Cite

show abstract

“…The increase in the glomerular filtration rate induced by a protein meal is lower in subjects with high hydration levels than those with low hydration levels (Hadj-Aissa et al, 1992) (Figure 5c). Recently, a positive correlation has been observed between the glomerular filtration rate and urine osmolality with normal fluid intake, but not in the context of water diuresis (Anastasio et al, 2001) (Figure 5d). The normal human glomerular filtration rate is approximately 150 l/day, and 95-99.5% of the water and 99% of the sodium are reabsorbed.…”

Section: Renal Consequences Of a High Level Of Vasopressin In A Healtmentioning

confidence: 92%

Mild dehydration, vasopressin and the kidney: animal and human studies

Bouby

Fernandes

2003

Eur J Clin Nutr

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Water balance depends essentially on fluid intake and urine excretion. Mild dehydration and the consequent hypertonicity of the extracellular fluid induce an increase in vasopressin secretion, thus stimulating urine concentrating processes and the feeling of thirst. The osmotic threshold for the release of vasopressin is lower than that for thirst and also shows appreciable individual variation. Sustained high levels of vasopressin and low hydration induce morphological and functional changes in the kidney. However, they could also be risk factors in several renal disorders, such as chronic renal failure, diabetic nephropathy and saltsensitive hypertension.

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“…In their very cautious analysis of these findings, the authors (21) point out: 1) that the correlations are not necessarily causal (although they may involve the effect of hydration on hemorheological variables such as blood viscosity); 2) that the findings might be unique to Seventh Day Adventists living in California, especially since they drink considerably more water and less caffeinated and alcoholic drinks than do other groups; 3) that the trends in the risks are significant only in men, whereas in women the risk of fatal coronary heart disease was as low as or lower in those drinking three or four glasses of water a day (711 to 948 ml) as in those who drank five or more glasses; and 4) that other 2 If, instead of the assumed 1,000 ml for water in solid food ( (29); some experts now quote a value of 500-750 ml for water derived from solid food (49)], then the calculated "water as fluid" of 1,675 ml comes astonishingly close to the 1,696 figure reported by Ershow and Cantor (Table 2). Total fluid intake 1,440 ml studies, likely ones with experimental design, will be needed to confirm the findings.…”

Section: Prevention Of Cancer Heart Disease and Other Conditionsmentioning

confidence: 99%

“Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8”?

Valtin¹

2002

American Journal of Physiology-Regulatory, Integrative and Comp

179

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Despite the seemingly ubiquitous admonition to “drink at least eight 8-oz glasses of water a day” (with an accompanying reminder that beverages containing caffeine and alcohol do not count), rigorous proof for this counsel appears to be lacking. This review sought to find the origin of this advice (called “8 × 8” for short) and to examine the scientific evidence, if any, that might support it. The search included not only electronic modes but also a cursory examination of the older literature that is not covered in electronic databases and, most importantly and fruitfully, extensive consultation with several nutritionists who specialize in the field of thirst and drinking fluids. No scientific studies were found in support of 8 × 8. Rather, surveys of food and fluid intake on thousands of adults of both genders, analyses of which have been published in peer-reviewed journals, strongly suggest that such large amounts are not needed because the surveyed persons were presumably healthy and certainly not overtly ill. This conclusion is supported by published studies showing that caffeinated drinks (and, to a lesser extent, mild alcoholic beverages like beer in moderation) may indeed be counted toward the daily total, as well as by the large body of published experiments that attest to the precision and effectiveness of the osmoregulatory system for maintaining water balance. It is to be emphasized that the conclusion is limited to healthy adults in a temperate climate leading a largely sedentaryexistence, precisely the population and conditions that the “at least” in 8 × 8 refers to. Equally to be emphasized, lest the message of this review be misconstrued, is the fact (based on published evidence) that large intakes of fluid, equal to and greater than 8 × 8, are advisable for the treatment or prevention of some diseases and certainly are called for under special circumstances, such as vigorous work and exercise, especially in hot climates. Since it is difficult or impossible to prove a negative—in this instance, the absence of scientific literature supporting the 8 × 8 recommendation—the author invites communications from readers who are aware of pertinent publications.

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Level of hydration and renal function in healthy humans

Abstract: In fasting adults, high hydration lowered GFR and increased natriuresis. After a meat meal, GFR increased only in the high hydration regimen and natriuresis only in the low hydration regimen. Hydration affects GFR and natriuresis under fasting conditions and after a meat meal.

Cited by 91 publications

References 12 publications

Urine Volume and Change in Estimated GFR in a Community-Based Cohort Study

Urine Volume and Change in Estimated GFR in a Community-Based Cohort Study

Mild dehydration, vasopressin and the kidney: animal and human studies

“Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8”?

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