Metabolites and Analogues of Vitamin D: Which for What?

The discovery and chemical synthesis of several biologically active derivatives of vitamin D have increased the number of compounds available for the treatment of disorders of bone and mineral metabolism. Calcitriol is the most active natural metabolite of vitamin D, but analogues like dihydrotachysterol and calcifediol also are safe and effective therapeutic agents. These vitamin D congeners have been useful in the treatment of renal osteodystrophy, hypoparathyroidism, and other disorders refractory to vitamin D therapy. Certain analogues may offer distinct advantages over vitamin D, depending on the nature of the defect. All vitamin D derivatives should be used cautiously, with frequent monitoring of serum calcium levels to prevent toxic reactions.