Objectives:
To evaluate the degree of tubular involvement in INS at various stage of the disease.
Methods:
19 patients with INS were studied. 13 were steroid responders (group 1). 5 of them had biopsy which showed MCD. 6 patients were non responder to steroid or were steroid dependant with frequent relapses (group 2). Biopsies showed 3 FSGS and 3 MCD. They were treated with prednisone, ciclosporin and/ or mycofenolate mofetil. Protein, microalbumin (ALB), alpha-microglobulin (AMG), N-acetyl-beta-D-glucosaminidase (NAG) and creatinine (cr) were measured in each urine sample. Patients were considered in remission if prot/ cr ratio (g/mol) was < 20 (group 1a and 2a), and in relapse if the ratio was > 200 (group 1c and 2c). Some patients in group 1 had non nephrotic proteinuria (group 1b). Tubular dysfunction was defi ned by NAG/cr ratio (mg/mmol) > 0.86 or by AMG/cr ratio (mg/mmol) > 1.58.
Results:
Prot/cr ALB/cr NAG/cr AMG/cr
Group 1a 10.3 ± 4.1 1.1 ± 1.0 0.19 ± 0.12 1.40 ± 0.97
Group 1b 60.4 ± 63.4 42.8 ± 66.7 0.39 ± 0.21 1.20 ± 0.56
Group 1c 713.3 ± 276.8 799.8 ± 534.9 2.25 ± 1.86* 4.25 ± 2.09*
Group 2a 11.3 ± 6.1 4.7 ± 5.7 0.26 ± 0.19 1.18 ± 0.60
Group 2c 914.9 ± 718.6 682.9 ± 589.3 3.00 ± 2.72* 5.47 ± 4.30*
Results are mean ± SD, p < 0.001 compared to group 1a and 2a
No difference was observed between group 1 and group 2 neither in remission nor in relapse.
Conclusions:
These data indicate that tubular dysfunction occurs in INS but only in patients in relapse. In this population, tubular dysfunction was independent of the severity of the nephrotic syndrome, the treatment protocol and the histopathology.