High Serum Level ofβ2-Microglobulin in Late Posttransplant Period Predicts Subsequent Decline in Kidney Allograft Function: A Preliminary Study

Abstract

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 (β2MG) in the late posttransplant period could predict a decline in KAG function.Methods.We assessed a value of single measurement of serumβ2MG 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 serumβ2MG 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. Higherβ2MG 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, serumβ2MG had excellent power in predicting certain drop in eGFR after one year (AUC = 0.910). In conjunction with posttransplant time serumβ2MG had good accuracy in predicting certain eGFR drop after two years (AUC = 0.821).Conclusions.Elevated serumβ2MG in the late posttransplant period is useful in identifying patients at risk for rapid loss of graft function.