[Vitamin D: clinical aspects and therapy].

This short review summarizes the metabolism and regulation of vitamin D3 with special emphasis on the regulation of renal 25-hydroxy-vitamin D3 1-alpha-hydroxylase. Vitamin D3 is of documented therapeutic utility in the following entities: Vitamin-D3 deficiency, involutional osteoporosis, glucocorticoid-induced osteoporosis and renal osteodystrophy. A therapeutic benefit of vitamin D3 is not yet established for hematological as well as for other neoplasias and for psoriasis. The introduction of noncalcemic vitamin-D3 analogs may lead to an increased use in these indications and will hopefully improve prevention and treatment of renal osteodystrophy.