The patients will be examined clinically at baseline and at 6, and 12 months. Laboratory assessments will be performed at screening and 1, 2, 3, 6, 9 and 12 months after baseline. MRI will be performed (T1-weighted and T2-weighted) at randomization and 12 months thereafter. Sample size is 80 patients: two groups with 40 patients in each group. The primary statistical analyses will be based on the intent-to-treat (ITT) population which consist of all randomized patients who have started study medication. The primary efficacy variable MRI T2 BOD will be analyzed using ANCOVA with MRI T2 BOD at baseline as covariate. The incidence (with corresponding 95% confidence interval) of hypercalcaemia (mild, moderate and severe), laboratory abnormalities, dose adjustments, and significant adverse events will be calculated. The vitamin D status (proportion of patients with P-PTH \<20 ng/l and S-OH(D)2 \>85 nmol/l) at 6 and 12 months will be analyzed using logistic regression.
