Proteinuria is the predominant risk factor for renal disease progression in Fabry disease
(FD). When urine protein excretion is controlled to <0.50 g/24 hr, the rate loss of
glomerular filtration rate (GFR) is not significantly different from 0. However, enzyme
replacement therapy (ERT) alone does not decrease proteinuria and it has been recommended
that patients receiving ERT also receive anti Renin-Angiotensin-System (RAS) therapy.
Emerging evidences show that paricalcitol (PCT) reduces proteinuria in presence of
intensified inhibition of RAS; however, there is no evidence in FD. The aim of this study is
to evaluate the antiproteinuric effect of PCT in FD patients with proteinuria >0.50 g/24 hr
persisting despite the ERT and anti-RAS therapy titrated to maximum tolerated dosage.