Trauma & Others(구연) (E-234) Skeletal muscle mass effects on estimated-GFR decremant after donor nephrectomy Urology, Yongin Severance Hospital, Internal Medicine, Endocrinology, Severance Hospital, Urology, Severance Hospital, Internal Medicine, Endocrinology, Severance Hospital, Urology, Severance Hospital Joon Chae Na, Namki Hong, Min-Gee Yoon, Yumie Rhee, Woong Kyu Han Background: Estimated glomerular filtration rate(eGFR) based on serum creatinine is commonly used to follow the renal function of patients after nephrectomy. Although it is well known that skeletal muscle mass influences the level of serum creatinine, the effect of skeletal muscle mass on decreased renal function after acute nephron loss is not known.  / Objectives: In this study we aimed to evaluate the effect of skeletal muscle mass on eGFR calculated by serum creatinine and cystatin C. / Materials and Methods: From our kidney donor database, 601 donors were randomly selected in even distribution across age and sex. Skeletal muscle area(SMA), skeletal muscle density(SMD) was extracted from the L3 level slice on predonation CT scan. Skeletal muscle index(SMI) was calculated by correcting SMA for height: SMA/height2. The association between the skeletal parameters and predonation eGFR derived from multiple methods, and with decreased eGFR ratio – calculated from serum creatinine and cystatin C - at 6 month postdonation compared to predonation were analyzed by linear regression analysis. / Results and Conclusion: Among the selected donors skeletal muscle parameters were extracted from 592 donors. The skeletal muscle parameters were significantly different according to sex: SMA cm2 168.0±23.1 vs 109.4±13.8, SMD(Hounsfield Units, HU) 45.2±5.2 vs 39.5±6.0, and SMI cm2/m2 57.0±7.2 vs 43.1±5.1 (all p<0.001). All skeletal parameters were significantly associated with age, sex and BMI. There was a significant correlation between predonation creatinine based eGFR and SMA and also SMI. No correlation was seen between skeletal muscle parameters and cystatin based eGFR or DTPA measured GFR (Table1). SMA and SMI had negative correlation with the %change of creatinine based eGFR at 6month post donation in male donors but not in female donors (Table2). The association of %change of cystatin C based eGFR with all skeletal muscle parameters were not significant. (Figure1) CONCLUSION: Male kidney donors with high SMA or SMI are more likely to have decreased creatinine based eGFR after donation. However as this is not seen in cystatin C based eGFR this phenomenon is more likely associated with skeletal muscle mass rather than a reflection of true decrease in GFR. Cystatin C based eGFR may reflect postdonation GFR more accurately in muscular male donors.