Klein G L, Herndon D N
Department of Pediatrics, University of Texas Medical Branch, Galveston, USA.
Magnes Res. 1998 Jun;11(2):103-9.
Children and adults who are severely burned develop magnesium(Mg) depletion, hypocalcemia, hypoparathyroidism and renal resistance to the administration of exogenous parathyroid hormone(PTH). This same spectrum of findings is seen with both Mg depletion and hypermagnesemia. We reported that in a group of ten children burned at least 30 per cent of total body surface area that 70-80 per cent of serum levels of ionized calcium and Mg were low. In three of the patients studies when serum Mg returned to normal, retention of a standard Mg infusion was abnormally high in two of them, suggesting persistence of Mg depletion despite normal serum Mg levels. Mg intake in these children conforms to the recommended dietary intake for age suggesting that excessive Mg losses may contribute to the observed Mg depletion. These losses are through the burn wound and possibly through abnormal intestinal secretion. Increased metabolic rate seen in burn patients may also promote intracellular Mg uptake to support the increased energy requirements of cells. It is hypothesized that since Mg is an important cofactor in the production of cyclic AMP, Mg deficiency may block intracellular cyclic AMP generation in parathyroid cells to block the secretion of parathyroid hormone and in renal tubular cells to block the renal generation may improve PTH secretion and hypocalcemia in non-burned patients, preliminary data in burned children suggest that the cause of hypocalcemia and hypoparathyroidism is more complex.
严重烧伤的儿童和成人会出现镁（Mg）缺乏、低钙血症、甲状旁腺功能减退以及肾脏对外源性甲状旁腺激素（PTH）给药的抵抗。在镁缺乏和高镁血症中都能看到相同的一系列表现。我们报告称，在一组全身表面积至少烧伤30%的10名儿童中，70 - 80%的血清离子钙和镁水平较低。在其中3名接受研究的患者中，当血清镁恢复正常时，其中2人的标准镁输注保留率异常高，这表明尽管血清镁水平正常，但镁缺乏仍然持续存在。这些儿童的镁摄入量符合年龄推荐的饮食摄入量，这表明过量的镁流失可能导致了观察到的镁缺乏。这些流失是通过烧伤创面，也可能是通过异常的肠道分泌。烧伤患者中可见的代谢率增加也可能促进细胞内镁的摄取，以支持细胞增加的能量需求。据推测，由于镁是环磷酸腺苷（cAMP）产生中的重要辅助因子，镁缺乏可能会阻断甲状旁腺细胞内cAMP的生成，从而阻断甲状旁腺激素的分泌，在肾小管细胞中阻断肾脏生成可能会改善非烧伤患者的PTH分泌和低钙血症，但烧伤儿童的初步数据表明，低钙血症和甲状旁腺功能减退的原因更为复杂。
