Serum cystatin C as a determinant of fasting total homocysteine levels in renal transplant recipients with a normal serum creatinine

Serum creatinine, a surrogate for both renal function and homocysteine gene ration, is an important determinant of fasting plasma total homocysteine le vers in stable renal transplant recipients. In this study, it is hypothesiz ed that among stable renal transplant recipients with normal creatinine lev els (i.e., less than or equal to 1.5 mg/dl), serum cystatin C, a more sensi tive indicator of GFR, would better predict fasting total homocysteine leve ls compared with serum creatinine. Fasting plasma total homocysteine, folat e, vitamin B-12, and pyridoxal 5'-phosphate levels, along with serum cystat in C, creatinine, and albumin levels, were determined in 28 consecutive ren al transplant recipients (mean age 47 +/- 14 yr; 60.7% men) with stable all ograft function, whose serum creatinine was less than or equal to 1.5 mg/dl . General linear modeling with analysis of covariance revealed that serum c ystatin C was independently predictive (partial R = 0.494; P = 0.023) of fa sting total homocysteine levels after adjustment for age, gender, vitamin s tatus, albumin, and creatinine levels. In contrast, creatinine levels were not predictive of fasting total homocysteine levels in this model (P 0.110) or an identical model that excluded cystatin C (P = 0.131). Serum cystatin C levels may reflect subtle decreases in renal function that independently predict fasting total homocysteine levels among stable renal transplant re cipients with a normal serum creatinine.