Figure 87

Renal involvement in sarcoidosis. The principal manifestations of renal involvement in sarcoidosis are the functional abnormalities resulting from the altered metabolism of calcium as a result of the increased synthesis of 1,25-dihydroxy-vitamin D3 by the macrophages of the granulomatous lesions. The consequent increased calcium absorption from the gastrointestinal tract results in the hypercalciuria that can be detected in more than half of patients. The frequency of hypercalciuria depends on the extent of granulomatous lesions and on the time of the year, being more common in spring and summer when exposure to the sun is greatest. Hypercalcemia is less common and usually depends on coexistent deterioration of renal function when the capacity of the kidney to excrete calcium is compromised. In most patients, hypercalciuria is asymptomatic. Its principal manifestations are inability to concentrate the urine and polyuria. Nephrolithiasis occurs in about 10% of patients; another 10% develop nephrocalcinosis.

Abnormal calcium metabolism and pathophysiology of renal involvement in sarcoidosis

Abnormal calcium metabolism and pathophysiology of renal involvement in sarcoidosis

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