Simerjot K Jassal1, Christina L Wassel2, Gail A Laughlin3, Elizabeth Barrett-Connor3, Dena E Rifkin4, Joachim H Ix5. 1. Primary Care Service, VA San Diego Healthcare System, San Diego, California; Division of General Internal Medicine, Department of Medicine, University of California, San Diego, La Jolla, California. Electronic address: sjassal@ucsd.edu. 2. Division of Epidemiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania. 3. Division of Epidemiology, Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, California. 4. Division of Nephrology, Department of Medicine, University of California, San Diego, La Jolla, California; Section of Nephrology, Medicine Service, VA San Diego Healthcare System, San Diego, California. 5. Division of Epidemiology, Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, California; Division of Nephrology, Department of Medicine, University of California, San Diego, La Jolla, California; Section of Nephrology, Medicine Service, VA San Diego Healthcare System, San Diego, California.
Abstract
OBJECTIVES: To determine whether a previously developed and externally validated equation using common variables (demographics and weight) that are important determinants of muscle mass to estimate 24-hour urine creatinine excretion rate (eCER) is associated with muscle mass and whether spot urine creatinine (UCr) provides similar estimates of muscle mass. DESIGN: Observational cross-sectional cohort study. SETTING: The Rancho Bernardo Study, San Diego, California. SUBJECTS: A total of 1,371 Caucasian, middle class, community-dwelling older adults. INTERVENTION: Morning spot UCr and fat-free mass (FFM) by dual-energy x-ray absorptiometry were measured. eCER was calculated: eCER (mg/day) = 879.89 + 12.51 × weight (kilogram) - 6.19 × age + 34.51 if black - 379.42 if female. Pearson correlation coefficients and linear regression were used to determine strengths of association of eCER and spot UCr with FFM. RESULTS: Mean age was 70 years, and 58% were women. eCER was strongly correlated with FFM (r = 0.95, P < .001), a correlation that was superior to that of spot UCr (r = 0.40, P < .001). CONCLUSIONS: An equation incorporating age, weight, sex, and race to estimate eCER is highly correlated with FFM in community-dwelling older persons and provides a more precise estimate than spot UCr. A simple screening tool for sarcopenia in older persons may allow interventions to maintain or improve muscle mass. Future studies should evaluate whether eCER predicts sarcopenia-related frailty and mortality in older persons. Published by Elsevier Inc.
OBJECTIVES: To determine whether a previously developed and externally validated equation using common variables (demographics and weight) that are important determinants of muscle mass to estimate 24-hour urine creatinine excretion rate (eCER) is associated with muscle mass and whether spot urine creatinine (UCr) provides similar estimates of muscle mass. DESIGN: Observational cross-sectional cohort study. SETTING: The Rancho Bernardo Study, San Diego, California. SUBJECTS: A total of 1,371 Caucasian, middle class, community-dwelling older adults. INTERVENTION: Morning spot UCr and fat-free mass (FFM) by dual-energy x-ray absorptiometry were measured. eCER was calculated: eCER (mg/day) = 879.89 + 12.51 × weight (kilogram) - 6.19 × age + 34.51 if black - 379.42 if female. Pearson correlation coefficients and linear regression were used to determine strengths of association of eCER and spot UCr with FFM. RESULTS: Mean age was 70 years, and 58% were women. eCER was strongly correlated with FFM (r = 0.95, P < .001), a correlation that was superior to that of spot UCr (r = 0.40, P < .001). CONCLUSIONS: An equation incorporating age, weight, sex, and race to estimate eCER is highly correlated with FFM in community-dwelling older persons and provides a more precise estimate than spot UCr. A simple screening tool for sarcopenia in older persons may allow interventions to maintain or improve muscle mass. Future studies should evaluate whether eCER predicts sarcopenia-related frailty and mortality in older persons. Published by Elsevier Inc.
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