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.