Background and objectives: For addressing the influence of muscle mass on serum and urinary creatinine and serum cystatin C, body composition was assessed by skinfold thickness measurement and bioelectrical impedance analyses.Design, setting, participants, & measurements: A total of 170 healthy individuals (92 women, 78 men) were classified as sedentary or with mild or moderate/intense physical activity. Blood, 24-h urine samples, and 24-h food recall were obtained from all individuals.Results: Serum and urinary creatinine correlated significantly with body weight, but the level of correlation with lean mass was even greater. There was no significant correlation between body weight and lean mass with cystatin C. Individuals with moderate/intense physical activity presented significantly lower mean body mass index (23.1 ؎ 2.5 versus 25.7 ؎ 3.9 kg/m 2 ) and higher lean mass (55. A multivariate analysis of covariance showed that lean mass was significantly related to serum and urinary creatinine but not with cystatin, even after adjustment for protein/meat intake and physical activity.3Conclusions: Cystatin C may represent a more adequate alternative to assess renal function in individuals with higher muscle mass when mild kidney impairment is suspected.Clin J Am Soc Nephrol 3: 348-354, 2008348-354, . doi: 10.2215 A ccurate renal function measurements are important in the diagnosis and treatment of kidney diseases, adjustment of drug dosages, and decision-making regarding when to initiate renal replacement therapy. Serum creatinine is the most commonly used indicator of renal function, but its measurement suffers from a variety of analytical interferences and significant standardization problems (1,2).Serum creatinine can be affected by age, gender, ethnicity, dietary protein intake, and lean mass and may remain within the reference range despite marked renal impairment in patients with low muscle mass. Consequently, the sensitivity of serum creatinine for the early detection of kidney disease is poor and not a good predictor when analyzing the elderly (3,4). Conversely, theoretically, serum creatinine may be falsely increased in individuals with higher muscle mass and normal renal function.The GFR represents the best overall assessment of kidney function, but the gold standard techniques for the measurement of GFR, such as inulin clearance, [125 I]iothalamate, 51 Cr-EDTA, 99m Tc-diethylenetriaminepentaacetic acid, and iohexol are too labor-intensive and costly for routine clinical use (5,6), so creatinine clearance is used instead.To rid the need of 24-h urine collections, several serum creatinine-based prediction formulas have been proposed to predict GFR (7-16). The equations of Cockcroft and Gault (7,8) and the one derived from the Modification of Diet in Renal Disease (MDRD) study (10) are the most widely accepted; however, the competence of such formulas to predict GFR in patients with normal values of serum creatinine is debated.Despite the important influence of muscle mass on serum creatinine, the differ...

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Background: Hypothyroidism is an important public health problem in Bangladesh. It is associated with increased risk for atherosclerosis and other complications. The frank development of hypothyroidism is associated with metabolic derangements including dyslipidemia- which is an etiopathologic factor for development of renal impairment. This study was to evaluate whether hypothyroidism is associated with impaired renal function. Methods: Using a cross sectional analytical study design, a total of 111 subjects attending Out Patient Department, Center for Nuclear Medicine and Ultrasound, Bogra Medical College during January 2007 to December 2007 were included purposively. Eighty newly diagnosed hypothyroid patients (Group I) and 31 healthy adults (Group II) were enrolled in this study. Serum thyroid stimulating hormone and serum free thyroxine were assayed by radioimmunoassay. Serum fasting lipid profile, serum creatinine and serum uric acid were estimated by enzymatic colorimetric method. Estimated GFR was calculated using MDRD equation. Results: The mean (±SD) age of in Group I and Group II were 35.59 (±6.91) and 37.35 (±2.78) years and were comparable. In Group I, there were 66 females and 14 males. In Group II, there were 16 females and 15 males. The mean BMI was 25.49 ±2.17 kg/m2 in Group I and 24.24 ±1.99 kg/m2 in Group II. The mean (±SD) Serum total-cholesterol, LDL- cholesterol and tryacylglycerol in Group I were significantly higher than that in Group II. Serum HDL cholesterol in Group I was significantly lower than that in Group II (p<0.001). The mean (±SD) serum creatinine was significantly higher in Group I than Group II (P<0.001). The estimated glomerular filtration rate (eGFR) was lower in Group I compared to Group II (p=0.011). In Group I (Hypothyroid), there were significant correlations of BMI, S Total-Cholesterol, S HDLCholesterol, S LDL-Cholesterol, S triglycerides and S creatinine with serum TSH level. In Group I (Hypothyroid), there were significant positive correlations of BMI and TSH with serum creatinine. Conclusions: Hypothyroidism is associated with dyslipidemia, hyperuricemia and impaired renal function. Therefore, patients presenting with these biochemical abnormalities are recommended to be investigated for hypothyroidism and vice versa. DOI: http://dx.doi.org/10.3329/bjmb.v6i1.13283 Bangladesh J Med Biochem 2013; 6(1): 19-25