You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Cause of nephrocalcinosis in granulomatous ds - and explain in detail?
<p>In patients with sarcoidosis and other granulomatous diseases, such as tuberculosis and fungal infections, excess 1,25(OH) 2 D is synthesized in macrophages or other cells in the granulomas.Indeed, increased 1,25(OH) 2 D levels have been repoed in anephric patients with sarcoidosis and hypercalcemia. Macrophages obtained from granulomatous tissue conve 25(OH)D to 1,25(OH) 2 D at an increased rate. There is a positive correlation in patients with sarcoidosis between 25(OH)D levels (reflecting vitamin D intake) and the circulating concentrations of 1,25(OH) 2 D, whereas normally there is no increase in 1,25(OH) 2 D with increasing 25(OH) D levels due to multiple feedback controls on renal 1a-hydroxylase . The usual regulation of active metabolite production by calcium and phosphate or by PTH does not operate in these patients. Clearance of 1,25(OH) 2 D from blood may be decreased in sarcoidosis as well. PTH levels are usually low and 1,25(OH) 2 D levels are elevated, but primary hyperparathyroidism and sarcoidosis may coexist in some patients.(harrison 18 pg 3108)</p>