Hypercalcemia in two patients with sarcoidosis and Mycobacterium avium intracellulare not mediated by elevated vitamin D metabolites.

INTRODUCTION: To describe 2 unusual cases of hypercalcemia due to granulomatous diseases with normal vitamin D metabolites and no other ready explanation for the hypercalcemia.
METHODS: We present the clinical, laboratory and pathologic findings of 2 patients with hypercalcemia and review previous reports of hypercalcemia in granulomatous diseases without elevated vitamin D metabolites.
RESULTS: Hypercalcemia was described in various granulomatous diseases including sarcoidosis, tuberculosis, berylliosis, leprosy and, rarely, in fungal infections. Elevated serum level of vitamin D or its metabolites was linked to the pathogenesis of hypercalcemia in these disorders. The authors present the clinical, laboratory and pathologic findings in 2 patients who presented with hypercalcemia and normal vitamin D metabolites with no other ready explanation for the hypercalcemia. The first patient was diagnosed with Mycobacterium avium, whereas the second patient was found to have sarcoidosis.
CONCLUSION: Although hypercalcemia in granulomatous diseases has been attributed to be mediated by elevated vitamin D metabolites, there have been several case reports that documented normal values of active vitamin D metabolites. This report illustrates the regulatory feedback mechanisms of vitamin D synthesis and introduces the term "inappropriately normal" vitamin D metabolites levels in light of low levels of parathyroid hormone.