Calcium metabolism in sarcoidosis and its clinical implications

Objective. To examine the clinical implications of disturbed calcium metabo lism in sarcoidosis and how the pathophysiology affects management strategi es. Methods. The literature concerning calcium metabolism in sarcoidosis was re viewed. Results. Dysregulated calcium metabolism is a well-recognized complication of sarcoidosis, resulting in hypercalcaemia (prevalence 5-10%), hypercalcur ia (40-62%) and reduced bone density (40-55%). Extrarenal synthesis of calc itriol [1,25(OH)(2)D-3] is central to the pathogenesis of abnormal calcium homeostasis, but alterations in parathyroid hormone (PTH) activity and the expression of PTH-related peptide have also been demonstrated. The immunosu ppressive properties of calcitriol suggest that the raised levels seen in s arcoidosis could represent an adaptive response to the undefined antigen th at causes sarcoidosis. Conclusions. The mechanisms of abnormal calcium metabolism in sarcoidosis n eed to be understood when treating hypercalcaemia, hypercalcuria and cortic osteroid-induced osteoporosis. Studies are required to determine if the cur rently available therapies for osteoporosis are safe and effective in sarco idosis.