TUBULAR AND GLOMERULAR PROTEINURIA IN DIAGNOSING CHRONIC ALLOGRAFT NEPHROPATHY WITH RELEVANCE TO THE DEGREE OF URINARY ALBUMIN EXCRETION

Abstract

P300 Aims: The diagnosis of chronic allograft nephropathy (CAN) is based on pathological examination according to Banff’97 schema. The aim of the study was to evaluate the usefulness of tubular and glomerular proteinuria in non-invasive recognition of CAN. Methods: 130 renal allograft recipients (at least 90 days after transplantation) who have undergone renal allograft biopsy due to either of following indications (proteinuria, increase of serum creatinine, protocol biopsy), without urinary tract infection or obstruction were included in the study. Beta2-microglobulin (b2-m), alpha1-microglobulin (a1-m), albumin (alb), immunoglobulin G (IgG), total protein (Tp) and creatinine (ucr) concentrations were obtained from the second morning urine specimen. Raw data and values calculated per 1 gram of creatinine excreted in urine along with time after transplantation, serum creatinine (scr), and its change over period of 2 months prior to biopsy were taken for analysis. Urine proteins (b2-m, a1-m, alb, IgG) were measured using nephelometric method. Statistical calculations were performed using MANOVA and Stepwise Discriminant Analysis (SDA). Results: Statistical diagnosis and staging of CAN matched pathological method in 67.7% in preliminary SDA. Therefore patients were divided into normo- [(n-alb) <30 mg/1g ucr], micro- [(mic-alb) 30-300 mg/1g ucr], and macroalbuminuric [(mac-alb) >300 mg/1g ucr] group. Diagnoses obtained using SDA were in 89%, 91%, and 92% identical with the results of pathological examinations, for n-alb, mic-alb, mac-alb group, respectively. N-alb group: statistical analysis allows to correctly identify 100% (7 of 7), 90.6 % (29 of 32) and 80% (8 of 10) patients with CAN stage 0, 1, 2, respectively. Mic-alb group: statistical analysis allows to correctly identify 50% (1 of 2), 93.9 % (31 of 33) and 90% (9 of 10) patients with CAN stage 0, 1, 2+3, respectively. Mac-alb group: statistical analysis allows to correctly identify 100% (18 of 18), 83.3 % (15 of 18) patients with CAN stage 0+1, 2+3 (), respectively. Combination of groups in mic-alb and mac-alb group was necessary for statistical purposes. Tp (026), b2-m/1 g cr ratio (0.62), b2-m/1 g ucr ratio (0.59), were the most indispensable parameters for n-alb, mic-alb, and mac-alb group, respectively. Conclusions: Tubular and glomerular proteinuria measurement may be useful in non-invasive CAN diagnosis and stage prediction only with regard to degree of urinary albumin excretion.