ABSTRACT
The kidneys are less frequently affected by sarcoidosis than
other organs. Nevertheless, physicians taking care of sarcoi-
dosis patients need to be aware of the possibility of renal
involvement in order to diagnose this potentially fatal
complication early and treat it effectively. The kidneys may
be affected primarily by sarcoid granulomas or secondarily
from hypercalcemia, hypercalciuria, and nephrocalcinosis.
Hypercalcemia, an important complication of sarcoidosis,
results from over-production of 1,25-dihydroxyvitamin D3
(calcitriol) by activated macrophages and sarcoidosis gran-
ulomas. Calcitriol, in turn, causes increased absorption of
calcium from the gut. Hypercalcemia is not specific to
sarcoidosis: it is found in other granulomatous disorders
including tuberculosis, coccidioidomycosis, histoplasmosis,
leprosy, and granulomatous necrotizing vasculitis. Hyper-
parathyroidism and malignancy are two common non-
granulomatous causes of hypercalcemia.
