Patients with extrarenal production of 1,25(OH)D2 and primary hyperparathyroidism should have serial monitoring of 25-OH vitamin D and calcium during replacement to minimize the risk for hypercalcemia.
Vitamin D receptors are located in many tissues and many potential pleiotropic effects of vitamin D have been noted by researchers, but the data to date are insufficient for firm clinical conclusions about the magnitude of these effects. A number of other questions remain unanswered regarding vitamin D and its effects.
Reference
Evaluation, Treatment, and Prevention of Vitamin D Deficiency: An Endocrine Society Clinical Practice Guideline (J. Clin. Endocrinol. Metab. 2011;96:1911-30).