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 serum β2MG 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 β2MG 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 β2MG 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 β2MG had excellent power in predicting certain drop in eGFR after one year (AUC = 0.910). In conjunction with posttransplant time serum β2MG had good accuracy in predicting certain eGFR drop after two years (AUC = 0.821). Conclusions. Elevated serum β2MG in the late posttransplant period is useful in identifying patients at risk for rapid loss of graft function.

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The most investigations of the biomarkers of renal allograft dysfunction (RAD) are limited by early post-operational period and are aimed at diagnosis of acute rejection of renal transplant. This work has aimed to establish additional characteristics of chronic RAD by using non-invasive biomarkers of the blood serum and urine.Materials and methods. 79 patients aged 16 to 59 years (47 men and 32 women) took part in our retrospective study. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamil transferase (GGT), alkaline phosphatase (ALP), N-acetyl-β-D-glucosaminidase (NAG); interleukins (IL-2, IL-8, IL-10) and beta-2-microglobulin were evaluated.Results. Increased IL-10 and β2-MG serum concentration, and increased urinary concentration and activity of β2-MG, IL-2, IL-8, NAG, AP, AST, GGT were typical for chronic RAD. Only NAG was independently significantly associated with chronic RAD in multivariate regression. From the area under ROC-curves were derived, that β2-MG level in serum and urine, and the activity of NAG in urine had the excellent and good power to classify patients with satisfactory function and chronic RAD.Conclusions. The increase of β2-MG in serum and urine may indicate glomerular and tubular dysfunction, respectively. An increase of urinary NAG indicates the ongoing damage of the tubules. The increase of IL-2 and IL-8 in the urine and IL-10 in serum may indicate the etiology of chronic RAD.

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