Functional Defects in the Aging Kidney

Friedman, Sandor A.

doi:10.7326/0003-4819-76-1-41

Cited by 116 publications

(30 citation statements)

References 8 publications

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“…A fall in glomerular filtration rate with age was described by Davies and Shock [6] in 1950 and has subsequently been confirmed, in particular for Ccr [7], The decline in creatinine excretion with age is, however, less well recognized. We have demonstrated an almost linear decrease of about 50% (23.6 to 12.1 mg/kg) in creatinine excretion expressed in mg/kg/24 h over the 3rd to 9th decades, results which are remarkably similar to those of Siersb/ek-N ielsen et al [5] ( fig.…”

Section: Discussionmentioning

confidence: 99%

Prediction of Creatinine Clearance from Serum Creatinine

Cockcroft

Gault²

1976

Nephron

13,670

7,941

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A formula has been developed to predict creatinine clearance (C_cr) from serum creatinine (S_cr) in adult males: Ccr = (140 – age) (wt kg)/72 × S_cr(mg/100ml) (15% less in females). Derivation included the relationship found between age and 24-hour creatinine excretion/kg in 249 patients aged 18–92. Values for C_cr were predicted by this formula and four other methods and the results compared with the means of two 24-hour C_cr’s measured in 236 patients. The above formula gave a correlation coefficient between predicted and mean measured Ccr·s of 0.83; on average, the difference between predicted and mean measured values was no greater than that between paired clearances. Factors for age and body weight must be included for reasonable prediction.

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Section: Discussionmentioning

confidence: 99%

Prediction of Creatinine Clearance from Serum Creatinine

Cockcroft

Gault²

1976

Nephron

13,670

7,941

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“…On the other hand the concentrations of the major pharmacologically active metabolite, H119/66, which is excreted by the kidney, were higher in the older subjects. This presumably results from the deteriorating renal function which occurs with advancing age (Friedman, Raizner, Rosen, Soloman & Sy, 1972 The urinary excretion of unchanged metoprolol over 24 h was less in the elderly. After repeated administration the amount excreted was somewhat greater and this was due to an increase over the first 4 h in the young group and over the first 12 h of the older group.…”

Section: Discussionmentioning

confidence: 98%

The effect of age on the pharmacokinetics of metoprolol and its metabolites.

Quarterman¹,

Kendall²,

DeRuiter³

1981

Brit J Clinical Pharma

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1Plasma concentrations of metoprolol and a pharmacologically active metabolite, H119/66, have been measured in young and elderly volunteers after a single dose of 100 mg metoprolol tartrate and after repeated administration over a period of 1 week. Whilst concentrations of metoprolol are similar in each group, concentrations of H119/66 are approximately twice as high in the elderly. 2 Concentrations of unchanged metoprolol and of the major, but pharmacologically inactive, metabolite, H117/04, together with the two active metabolites of metoprolol have been determined in urine. Only the excretion of metoprolol was diminished in the elderly. 3 Areas under the plasma concentration curve for metoprolol after repeated administration are greater than would be predicted from single dose data, and possible explanations for this are discussed. Concentrations of the pharmacologically active metabolite, H119/66, remain unaltered during chronic dosing of metoprolol. 4 This study has shown that the effect of age on the pharmacokinetics of metoprolol and its metabolites is less pronounced than that observed for other drugs.

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“…Alternatively, the forces favoring filtration may be opposed by elevation of the intratubular hydrostatic pressure as a consequence of tubular obstruction (10). 16 Tubular Reabsorption and Secretion Each minute the kidneys produce 100 to 140 ml of glomerular filtrate with an osmolality of 280 to 290 mOsm/l. On a 24-hr basis this amounts to 150 to 200 liters of filtrate and over 400,000 mOsm of solute.…”

Section: Glomerular Filtrationmentioning

confidence: 99%

“…These anatomical abnormalities have functional correlates (16). Glomerular filtration rate and renal plasma flow decrease after age 40 years and are approximately 50% of normal by age 90 years.…”

Section: Effects Of Agingmentioning

confidence: 99%

Renal response to environmental toxics

Finn¹

1977

Environ Health Perspect

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Several characteristics of normal renal function increase the risk to the kidney of damage by environmental toxins. Due to the magnitude of renal blood flow the total amount of noxious substance delivered may be disproportionately high. Furthermore, the capacity to concentrate substances within the kidney by processes of filtration, reabsorption and secretion has the potential to increase the toxicity of agents which would otherwise not lead to tissue injury. Unfortunately, there are few tests of renal function which are able to detect early functional abnormalities and which, at the same time, are suited for screening purposes by virtue of their simplicity, cost and safety. Furthermore, interpretation of the tests is complicated by adaptive changes in renal function which occur with aging and in response to other disease processes. Environmental agents produce a wide spectrum of renal dysfunction. Acute renal damage follows exposure to glycols, organic solvents, heavy metals, diagnostic and therapeutic agents and a variety of miscellaneous substances. Chronic renal disease may take the form of isolated tubular defects as seen with cadmium, interstitial nephritis due to the ingestion of lead, or vascular damage induced by external radiation. Some forms of glomerulonephritis may also be related to environmental toxins as are certain tumors of the urinary tract. In a somewhat different fashion, patients whose renal function is limited by the presence of pre-existing disease may manifest toxicity from substances ordinarily excreted in the urine. Particular problems exist with the patients on dialysis, as they are at considerable risk to alterations in the environment.

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Functional Defects in the Aging Kidney

Cited by 116 publications

References 8 publications

Prediction of Creatinine Clearance from Serum Creatinine

Prediction of Creatinine Clearance from Serum Creatinine

The effect of age on the pharmacokinetics of metoprolol and its metabolites.

Renal response to environmental toxics

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