High Urinary Aspartate Aminotransferase in the Late Posttransplant Period Predicts Rapid, Progressive Decline in Kidney Allograft Function.

OBJECTIVES: Scant information is available on factors for predicting the rate of decline in kidney allograft function beyond 1 year posttransplant.We investigated whether urinary enzymes (alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, N-acetyl-ß-D-hexosaminidase, and ε-glutamyl transpeptidase) in the late postoperative period can predict the decline in estimated glomerular filtration rate. MATERIALS AND METHODS: In 79 kidney allograft recipients 1 to 17 years after kidney transplant, we assessed a value of urinary enzymes single measurement for predicting the slope of estimated glomerular filtration rate, rapid decline in estimated glomerular filtration rate (> 5 mL/min/1.73 m² /y), and significant decline in estimated glomerular filtration rate (≥ 25% from baseline) during a 2-year period. RESULTS: At baseline, patients with estimated glomerular filtration rate < 60 mL/min/1.73 m² (n = 54) differed from those with estimated glomerular filtration rate ≥ 60 mL/min/1.73 m² (n = 25) only in their lower median urinary alanine aminotransferase:creatinine ratio (expressed as U/L:mmol/L): 0.055 versus 0.222 (P = .011). Higher urinary activity of aspartate aminotransferase at baseline predicted the negative-slope value for estimated glomerular filtration rate (beta, -0.279; standard error, 0.131; P = .037) and decline in estimated glomerular filtration rate of > 5 mL/min/1.73 m ²/year (odds ratio, 2.06; 95% confidence interval, 1.10-3.83; P = .023) over 2 years. It also predicted the drop in estimated glomerular filtration rate ≥ 25% after 1 year (odds ratio, 2.62; 95% confidence interval, 1.07-6.37; P = .034) and 2 years (odds ratio, 2.75; 95% confidence interval, 1.12-6.73; P =.027). Combined with time after transplant, urinary aspartate aminotransferase had good power for predicting an estimated glomerular filtration rate decrease ≥ 25% after 2 years of follow-up. CONCLUSIONS: Higher urinary activity of aspartate aminotransferase in the late posttransplant period is useful for identifying transplant patients who are at risk for progressive loss of graft function.

High Serum Level of ß2-Microglobulin in Late Posttransplant Period Predicts Subsequent Decline in Kidney Allograft Function: A Preliminary Study.

BACKGROUND: Identification of patients at risk for kidney allograft (KAG) failure beyond the first posttransplant year is an unmet need. We aimed to determine whether serum beta-2-microglobulin (ß2MG) in the late posttransplant period could predict a decline in KAG function. METHODS: We assessed a value of single measurement of serum ß2MG at one to seventeen years after transplantation in predicting the estimated glomerular filtration rate (eGFR) and the decline in eGFR over a period of two years in 79 recipients of KAG. RESULTS: At baseline serum ß2MG concentration was higher (P = 0.011) in patients with allograft dysfunction: 8.67 ± 2.48 µg/mL versus those with satisfactory graft function: 6.67 ± 2.13 µg/mL. Higher ß2MG independently predicted the lower eGFR, the drop in eGFR by ≥25% after one and two years, and the value of negative eGFR slope. When combined with proteinuria and acute rejection, serum ß2MG had excellent power in predicting certain drop in eGFR after one year (AUC = 0.910). In conjunction with posttransplant time serum ß2MG had good accuracy in predicting certain eGFR drop after two years (AUC = 0.821). CONCLUSIONS: Elevated serum ß2MG in the late posttransplant period is useful in identifying patients at risk for rapid loss of graft function.