A patient with a granulomatous disease may develop hypercalcemia due to endogenous conversion of vitamin D by cells in the granulomas.


Mechanism: conversion of vitamin 25-(OH)-D3 to vitamin 1,25-(OH)2-D3


Clinical features:

(1) underlying granulomatous disease (sarcoid, tuberculosis, coccidioidomycosis or other deep fungal infection, leprosy)

(2) hypercalcemia and hypercalcuria

(3) normal plasma parathyroid hormone concentrations

(4) elevated serum vitamin 1,25-(OH)2-D3

(5) normocalcemia the steroid suppression test


Steroid suppression test (page 2.237, Thakker): Administration of hydrocortisone 40 mg tid for 10-14 days will result in normocalcemia in granulomatous hypercalcemia. Persistent hypercalcemia suggests a second or alternative cause.


Differential diagnosis:

(1) hypercalcemia in malignant lymphoma with a similar endogenous conversion of vitamin D

(2) vitamin D intoxication in food


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