Tubular damage and its relationship with effect of prednisone in patients with primary nephrotic syndrome in high altitude areas

Objective:To investigate tubular damage and its relationship with the treatment effect of prednisone in patients with primary nephrotic syndrome(PNS) in high altitude of 3 680 meters. Methods: The PNS patients were treated regularly with prednisone of 1 mg/(kg·d) for 8 weeks. They were divided into 2 groups according to the treatment effect. (1)Effective group( n =16): 24 h urinary protein excretion after treatment was ≤50% of that before treatment; (2)Ineffective group( n =12):24 h urinary protein excretion after treatment was 50% of that before treatment; (3)Normal control group( n =10). The urinary retinol binding protein(RBP) and N acetal D amino glucosidase(NAG)were measured by ELISA. The urinary osmosis, 24 h urinary protein excretion and serum creatinine (Cr) were measured. Results: (1) The urinary RBP[(0.54±0.19) mg/L], NAG[(112.84±42.82) U/L] and osmosis [(553.62±248.91) mmol/L] in PNS patients were significantly higher than normal control group ( P 0.01). (2) The urinary RBP [(0.33±0.16) vs (0.68±0.14 ) mg/L], NAG [(97.46±32.53) vs (158.65±12.98) U/L] and osmosis [(619.45±48.92 ) vs (337.81±26.56) mmol/L] showed significant difference( P 0.01) between effective and ineffective group before treatment while the 24 h urinary protein excretion, serum Cr demostrated no significant difference. (3) After 8 week treatment with prednisone, the urinary RBP, NAG and osmosis in effective group recovered to normal in contrast to no significant changes in ineffective group. Conclusion: Defect of renal tubular function exist in PNS patients in high altitude. Renal tubular function may be related with the prognosis of PNS patients in high altitude.