[Hypercalcemia caused by generalized sarcoidosis].

Abstract

HISTORY AND ADMISSION FINDINGS: A 70-year-old man with a 23-year history of recurrent nephrolithiasis was admitted for evaluation of hypercalcaemia (maximal calcium concentration 3.24 mmol/l). Physical examination on admission was unremarkable except for sensory neuropathy in the right foot. INVESTIGATIONS: Chest radiogram, subsequent transbronchial lung biopsy, gallium scintigraphy and magnetic resonance imaging (MRI) of the vertebrae indicated generalized sarcoidosis, predominantly affecting the mediastinum, lumbar vertebrae and nerves of the distal limbs. Parathormone level was reduced, while the levels of vitamin D metabolites were normal. TREATMENT AND COURSE: Serum calcium level became normal within 2 weeks of starting glucocorticoid treatment. CONCLUSION: Hypercalcaemia can occur in the course of sarcoidosis even in the absence of a elderly increased level of 1,25-dihydroxyvitamin D3. In this case the cause of the hypercalcaemia of a year's duration may have been due to lymphomacrophagocytic infiltration of the bone of several vertebrae as demonstrated by MRI of the vertebral columns but not by conventional radiography. In this case an increase in cytokine secretion by macrophages may have played an important role in addition to the level of 1,25-dihydroxyvitamin D3 at the upper limit of normal that, in view of the renal failure, could only have been caused by extrarenal production. Cytokines (e.g. interleukin-1 beta and tumour necrosis factor alpha) secreted by activated macrophages are among the most powerful stimulators of bone reabsorption.