[Role of paracalcitol in the management of non-dialysis CKD: state of art and... Unmet needs].

Chronic kidney disease (CKD) is associated with a high risk of cardiovascular morbidity and mortality due to the high prevalence of traditional risk factors and the presence of factors specific to CKD. Vitamin D deficiency and secondary hyperparathyroidism are the earliest complications in CKD, and observational data show that low plasma vitamin D is an independent predictor of death in patients with CKD. Oral supplementation with active oral vitamin D appears to be associated with greater survival but a significant improvement in renal outcome has not been demonstrated, probably because of its unwanted side effects (increase in plasma calcium and phosphate levels). Oral paracalcitol, a new vitamin D receptor activator, is now available for CKD patients not yet on dialysis. It suppresses PTH with a low incidence of increased serum calcium and phosphate levels in patients treated with dialysis and when high doses are administered. Furthermore, recent data show that paracalcitol treatment in CKD patients also results in a significant reduction of albuminuria, which is a major risk factor for cardiorenal outcome. The antiproteinuric effect of paracalcitol appears to be the result of intrarenal suppression of the renin-angiotensin system (RAS). Therefore, paracalcitol may be mostly effective in reducing albuminuria in patients already treated with RAS inhibitors who show compensatory increments of RAS components. Studies in large patients series and with adequate follow-up are needed to evaluate the effects of long-term paracalcitol treatment in CKD and its potential role in improving renal outcome in comparison not only with placebo but also other vitamin D metabolites and analogues.