IBMS BoneKEy | Perspective
Mild primary hyperparathyroidism and metabolism of vitamin D
Jens Bollerslev
Lars Rolighed
Leif Mosekilde
DOI:10.1138/20110522
Abstract
Mild primary hyperparathyroidism (PHPT) is a common condition in Western societies, as is vitamin D insufficiency. The prevalence of mild PHPT is high, especially in pre- and postmenopausal women (2-5%), and the incidence seems to be relatively constant at a slightly higher level, compared to the period before automated calcium measurements. As many as 80% of patients with mild (without organ-specific symptoms) PHPT present with 25-hydroxy vitamin D (25OHD) levels below 50 nmol/l (vitamin insufficiency). The reason for the frequent co-existence of vitamin D insufficiency and PHPT is not fully understood and cannot be explained solely by increased PTH-driven conversion to the active vitamin D metabolite, 1,25-dihydroxyvitamin D (1,25(OH)2D). Only three small, prospective studies have been performed within the last ten years on vitamin D repletion in mild PHPT, with ambiguous results. Vitamin D repletion might increase serum calcium levels and in general it is recommended to vitamin D-deplete patients before decision-making for final therapy (surgery). In addition, vitamin D repletion might decrease PTH levels due to binding to the vitamin D receptor in the parathyroid gland, but the results have not been unequivocal. Furthermore, no clear results regarding biochemical markers of bone turnover or bone mineral density have been presented. An increase in renal calcium excretion during vitamin D repletion is a concern and should be carefully monitored. The recommendation of vitamin D repletion in mild PHPT seems logical and reasonable, however, thus far this conclusion is not based on large-scale, randomized controlled studies. Such investigations are highly warranted.
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