Angiotensin II receptor blockers (ARBs) reduce proteinuria, however, with large inter-individual variability. The present study investigated whether urinary transforming growth factor-β1 (TGF-β1) might predict the antiproteinuric efficacy of ARB in non-diabetic chronic renal disease.

Non-diabetic patients with proteinuria (>1g/day) received 50mg of losartan daily followed by 100mg in two treatment periods, each lasting 12weeks. Clinical parameters and urinary TGF-β1 levels were measured at baseline and during the treatment period.

In the whole group of patients, losartan treatment effectively decreased proteinuria. However, considerable differences existed among individual antiproteinuric responses. Good (n=34) or low (n=15) responders showed average proteinuria reduction of 69% or 17% from baseline, respectively. Both groups showed similar baseline biochemical and renal parameters and comparable degree of mean arterial blood pressure (MAP) reduction. However, the low responders were older and showed significantly higher baseline urinary TGF-β1 levels. On multiple regression analysis, age, baseline urinary TGF-β1 and % reduction in urinary TGF-β1 and % reduction in MAP significantly predicted antiproteinuric response to losartan therapy.

The present data suggest that the determination of baseline urinary TGF-β1 could be an useful indicator of short-term antiproteinuric response to ARB treatment in non-diabetic nephropathy.