Temporally associated with the improvement in
vitamin D nutrition in many Western countries in the mid-20th century, there was a change in many characteristics of
primary hyperparathyroidism.
Osteitis fibrosa cystica became a rare manifestation of what is now frequently an
asymptomatic disease. At the same time, in patients with the disease, levels of PTH and
parathyroid adenoma weights have fallen dramatically. In view of these observations and others, an association between
vitamin D deficiency and severity of
primary hyperparathyroidism has been proposed. Data support an association on two distinct levels. First, regardless of the clinical severity of
primary hyperparathyroidism, the disease seems to be more severe in those with concomitant
vitamin D deficiency. Second,
vitamin D deficiency and insufficiency seem to be more prevalent in patients with
primary hyperparathyroidism than in geographically matched populations. The association between
vitamin D deficiency and
primary hyperparathyroidism has clear implications. Co-existing
vitamin D deficiency may cause the serum
calcium level to fall into the normal range, which can lead to diagnostic uncertainty. With regard to management, preliminary data on
vitamin D repletion in patients with mild
primary hyperparathyroidism suggest that, in some cases, correction of
vitamin D deficiency may be accomplished without worsening the underlying
hypercalcemia.
Vitamin D-deficient patients undergoing
parathyroidectomy are also at increased risk of postoperative
hypocalcemia and "hungry bone syndrome," which underscores the importance of preoperative assessment of
vitamin D status in all patients with
primary hyperparathyroidism.