A method of treating and preventing secondary hyperparathyroidism in CKD by increasing or maintaining blood concentrations of both 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D in a patient by administering 25-hydroxyvitamin D3 with or without 25-hydroxyvitamin D2 and, as necessary, 1,25-dihydroxyvitamin D2 as a Vitamin D hormone replacement therapy.
