Transient Reversal of Hyperabsorption of Calcium and of Abnormal Sensitivity to Vitamin D in a Patient with Sarcoidosis During Episode of Nephritis

Abstract

Ca and P balance studies were carried out in a 41-year old man with sarcoidosis, hypercalcemia, hypercalciuria and renal stones before and after he developed acute glomerulonephritis and nephrosis. Calcium absorption was also determined with Ca47. The effects of prednisone (50 mg a day for 12 or 20 days) and of vitamin D (10,000 units a day for 12 days) were studied. Initially, there was excessive intestinal absorption of Ca which could be decreased with prednisone and increased with vitamin D. With the onset of nephritis, Ca absorption fell, producing hypocalcemia and hypocalciuria, and was not increased with vitamin D. The nephritis and the defect in Ca absorption did not persist, and hyperabsorption of Ca recurred spontaneously. The results support the hypothesis that the abnormality in Ca absorption in sarcoidosis results from increased sensitivity to vitamin D. They also indicate that the defect in calcium absorption with renal insufficiency is associated with decreased sensitivity to vitamin D.