SERUM CREATININE TO BODY WEIGHT RATIO-A SIMPLE MEAUSRE OF BODY COMPOSITION

Abstract

Body composition is not routinely measured in clinical practice in HD pts. Therefore, we examined whether serum creatinine (SCr) (a muscle mass marker in HD pts) to weight (wt) ratio is associated with measures of body composition and functional ability. 116 HD pts from an longitudinal study of nutritional status underwent at least one DEXA scan for measurement of body composition. Height, wt and 6-min walk distance were measured on a non-HD day. Intra-abdominal fat at the L4-L5 level and muscle area at mid thigh level were measured with MRI. Generalized estimating equations (GEE) were used to fit a pooled cross-sectional regression model relating outcomes to concurrently measured SCr/Wt across 4 study visits. SCr/wt 0.14 0.10-0.14 0.10 SCr, mg/dL 12.0±3.0 9.6 ± 1.7 6.9±1.9 Wt, kg 65±16 83 ± 15 89±8 Age,yr 43±16 51 ± 14 58±15 Men, %* 58 55 59 DM, % 11 55 62 BMI, kg/m 23.2±4.5 29.0±4.7 30.8±5.7 Intra-abdominal fat, cm 79±43 140±68 167±65 Muscle area, cm 109 29 108 28 104 26 DEXA fat mass/wt ,% 25±9 34±9 39±18 6-min walk distance, m 372±109 313±110 244±78 In a multivariable GEE regression, adjusted for age, gender, race and DM, compared to the highest tertile of Scr/Wt, the lowest tertile was associated with lower 6 min walk distance (β -61, 95% CI -94 to -29 m). Results were similar when these models were further adjusted for wt. SCr/Wt is associated with direct measures of body composition and correlates with physical function. The specific functional form of SCr/ Wt which scales optimally with body composition needs to be determined.