Vitamin D deficiency is considered as an inciting factor which is associated with further increases in parathormone serum levels. Moreover, vitamin D deficiency is associated with more severe expression of the disease manifestations. In countries where symptomatic primary hyperparathyroidism is common, severe vit D deficiency is also common among the general population.
Vit D deficiency should be treated using modest amounts of supplementation over several months. It has been shown that restoration of vit D to normal was associated with lower serum parathormone levels and improved lumbar spine bone mineral density.
Interestingly, vit D supplementation in primary hyperapathyroidism was not associated with any changes in serum or urinary calcium.