AIMS:Analyze urinary markers of proximal tubular dysfunction (PTD)(b2 microglobulin (b2m),N-acetyl-glucosaminidase (NAG) and Clara Cell Protein (CC16)) in kidney transplant (KT) patients, compared with a healthy control group. Analyze the value of these markers as prognostic factors for renal survival at 4 years of follow-up.

METHODS: Urinary levels of the 3 markers were measured, being expressed as a ratio with urinary creatinine. Clinical and biochemical features were collected.

RESULTS: 110 KT patients were studied, 68% male, mean age of 51,6±12,3 yr and a duration of KT of 7,8±5,8 yr. The etiology of CKD was diabetes in 25%, glomerulonephritis in 17%. 25% of patients had presented acute rejection, and 8% had chronic allograft dysfunction. 84% of patients were on triple therapy (78% FK and 20% CsA). Control group were 20 volunteers, mean age of 48,7±18,3 yr.

Mean levels of b2m, NAG and CC16 in KT patients were 8,1±16,6 g/g,4,4±3,7 U/g and 100,9±163,1 [micro]g/g respectively, significantly higher than controls 0,07±0,05(p<0,05), 2,3±1,2(p<0,05) and 3,6±2,8(p<0,05) respectively. We found high levels of b2m, NAG and CC16 in 81, 30 and 75% of patients. Classifying patients by quartiles of GFR, we observed significant higher levels of the 3 markers as GFR decreases. In patients with GFR>60ml/min, we still found high levels of b2m, NAG and CC16 in 70, 19,6 and 60,8% of patients, respectively. Diabetic patients had higher levels of the 3 markers compared with non-diabetic (b2m 13,9±209,6 vs 5,9±14,4 g/g, CC16 130±147 vs 91±169 [micro]g/g and NAG 6,1±3,9 vs 3,8±3,4 U/g,p<0,05). Both CC16 and b2m showed a negative correlation with GFR at 4 years after KT (r=-0,27, p<0,05 and r=-0,316,p<0,05), even with a better association than urinary albumin (r=-0,23, p<0,05). Patients that had initiated dialysis at the end of the study, had presented higher levels of b2m and CC16 (25,2±30,2 vs 5,5±12,1 g/g,p<0,05 and 275,5±642,9 vs 75,4±104,5 [micro]g/g, p<0,05). In patients with GFR>60 ml/min classified by levels of b2m, we found significant differences in calcium excretion, plasmatic levels of FK along the follow-up and with exposition time to cyclosporine. This is the 1st report of urinary CC16 in KT, with a good relation to b2m, serving as a new marker for PTD in KT.

CONCLUSIONS: PTD is highly prevalent in KT. Monitor urinary markers as b2m or CC16 can predict renal prognosis in KT. CC16 can be used as a new marker for PTD in KT.

CITATION INFORMATION: Garcia P, Garcia-Nieto V, Navarro J, Martin E, Rivero A, Jarque A, Gonzalez-Posadas J, Macia M. Urinary Markers of Proximal Tubular Dysfunction in Kidney Transplant as Predictors for CKD. Am J Transplant. 2016;16 (suppl 3).

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