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William B. Evans

Bio: William B. Evans is an academic researcher. The author has contributed to research in topics: Excretion & Phosphocreatine. The author has an hindex of 1, co-authored 2 publications receiving 15 citations.

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TL;DR: It is generally accepted that creatinine produced by endogenous metabolism is derived from muscle creatine and phosphocreatine, and this excretion rate is apparently independent of protein ingestion and is considered an index of muscle metabolism.
Abstract: It is generally accepted that creatinine produced by endogenous metabolism is derived from muscle creatine and phosphocreatine. The conversion is apparently the result of an irreversible process of normal metabolism which takes place at a constant rate, proportional to muscle mass and independent of muscular exercise.* The daily urinary excretion of creatinine is constant for the individual, ranging from 1.5 to 2.0 gm. for men and from 0.8 to 1.5 gm. for women. This corresponds to approximately 2% of the total body creatine, from which it is derived. This excretion rate is apparently independent of protein ingestion and is considered an index of muscle metabolism. It is not influenced by exercise or urine volume. Decreased creatinine excretion, with concurrent elevation in plasma level, is generally indicative of impaired renal function, since creatinine is freely filterable at the glomerulus. Decreased excretion in the absence of elevated plasma concentration is usually due

15 citations


Cited by
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TL;DR: The fundamental principles of physiology, metabolism, and analytical chemistry that are necessary to correctly interpret the serum creatinine concentration are reviewed and applied to important clinical circumstances, including aging, pregnancy, diabetes mellitus, drug administration, and acute and chronic renal failure.
Abstract: The serum creatinine concentration is widely interpreted as a measure of the glomerular filtration rate (GFR) and is used as an index of renal function in clinical practice. Glomerular filtration of creatinine, however, is only one of the variables that determines its concentration in serum. Alterations in renal handling and metabolism of creatinine and methodological interferences in its measurement may have a profound impact on the serum concentration of creatinine. We review the fundamental principles of physiology, metabolism, and analytical chemistry that are necessary to correctly interpret the serum creatinine concentration. These principles are then applied to important clinical circumstances, including aging, pregnancy, diabetes mellitus, drug administration, and acute and chronic renal failure. Despite numerous limitations, serum creatinine remains a useful clinical tool, but more accurate measures of renal function are frequently necessary.

1,550 citations

Journal ArticleDOI
TL;DR: While creatinine excretion may serve as a useful approximation of muscle mass in carefully selected subjects, there remains a need for accurate and practical indices of Muscle mass for use in the individuals in whom the method cannot be reliably applied.

812 citations

Journal ArticleDOI
TL;DR: Lower creatinine excretion rate is strongly associated with mortality in outpatients with coronary arteries disease, independently of conventional measures of body composition, kidney function, and traditional coronary artery disease risk factors.
Abstract: Background— In persons with coronary artery disease, low body mass index is associated with greater mortality; however, it is uncertain whether low muscle mass is a risk factor for mortality in this setting. Methods and Results— In this study, 903 individuals with coronary artery disease provided 24-hour urine collections. We measured urine creatinine and volume and calculated creatinine excretion rate, a marker of muscle mass. Cox proportional-hazards models evaluated the association of creatinine excretion rate with mortality risk. Over a median follow-up of 6.0 years, 232 participants (26%) died. Compared with the highest sex-specific creatinine excretion rate tertile, the lowest tertile ( 2-fold risk of mortality (hazard ratio, 2.30; 95% confidence interval, 1.51 to 3.51) in models adjusted for age, sex, race, cystatin C–based estimated glomerular filtration rate, body mass index, traditional cardiovascular disease risk factors, and C-reactive...

109 citations

Journal ArticleDOI
N. Thomas Ryan1
TL;DR: A review is presented which focuses on the major metabolic consequences of trauma and sepsis, examines the control mechanisms which are disrupted, and suggests possible biochemical explanations for certain components of the response.

97 citations