Dusso A, Finch J, Delmez J, Rapp N, Lopez-Hilker S, Brown A, Slatopolsky E
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.
Kidney Int Suppl. 1990 Sep;29:S36-40.
Under normal circumstances extrarenal sources of calcitriol probably constitutes a microendocrine system involved in cell differentiation and local intercellular communication with no influence on systemic calcium homeostasis. Under pathological conditions such as chronic renal failure, extrarenal sources have the potential to normalize serum calcitriol after adequate stimulation (such as, 25(OH)D administration). Extrarenal 1,25-(OH)2D3 synthesis is controlled by physiological levels of calcitriol. However, in sarcoidosis and other granulomatous diseases, 1,25-(OH)2D3 production by macrophages is deregulated, causing severe alterations in systemic calcium homeostasis.
在正常情况下，维生素D3的肾外来源可能构成一个参与细胞分化和局部细胞间通讯的微内分泌系统，对全身钙稳态没有影响。在慢性肾衰竭等病理条件下，肾外来源在充分刺激（如给予25(OH)D）后有使血清维生素D3正常化的潜力。肾外1,25-(OH)2D3的合成受维生素D3生理水平的控制。然而，在结节病和其他肉芽肿性疾病中，巨噬细胞产生1,25-(OH)2D3的过程失调，导致全身钙稳态严重改变。
