The reported incidence of hypercalcemia associated with sarcoidosis varies from 2% to 63%.1 Hypercalcemia tends to be transient in subacute sarcoidosis, but in chronic sarcoidosis, depending on the activity of the disease, the serum level of calcium may fluctuate.
What causes hypercalcemia in sarcoidosis? The available evidence indicates that it is due to increased intestinal absorption of calcium. The calcium balance studies by Henneman et al2 clearly demonstrate the association of hypercalcemia with increased urinary calcium and decreased fecal calcium excretion. They also noted that an explanation of hypercalcemia could not be based on an increased release of calcium from bone lesions. Most patients with bone lesions do not have hypercalcemia, whereas increased serum and urine calcium levels are observed in patients with no demonstrable osseous lesions. Neither abnormal serum proteins nor parathyroid hyperplasia play a role in producing hypercalcemia in sarcoidosis, according to Henneman et al3
Sharma OP. Hypercalcemia in SarcoidosisThe Puzzle Finally Solved. Arch Intern Med. 1985;145(4):626–627. doi:10.1001/archinte.1985.00360040044007