Ariceta G, Rodríguez-Soriano J, Vallo A
Department of Paediatrics, Hospital de Cruces, Bilbao, Spain.
Pediatr Nephrol. 1995 Aug;9(4):423-7. doi: 10.1007/BF00866716.
Renal handling of magnesium (Mg) has not been comprehensively studied in the newborn period due to the difficulty, until recently, of measuring the diffusible fraction of plasma Mg (UfMg). In the present study this methodology was used to assess Mg homeostasis in 84 newborn infants of different postconceptional age (26-42 weeks), weight (720-4,830 g) and postnatal age (1-72 days). Very premature infants (postconceptional age less than 35 weeks) had significantly higher values of plasma Mg than mature newborn infants. Plasma Mg related inversely to postconceptional age, weight, plasma total protein and plasma calcium, and directly to plasma potassium. Stepwise multiple regression analysis revealed that postconceptional age was the unique factor contributing to variations in plasma Mg. Plasma values of UfMg were the same in preterm as in term infants but, when expressed as a fraction of total plasma Mg (UfMg/Mg), they were significantly lower in very preterm infants. Fractional excretion of Mg and the ratio of urine Mg to urine creatinine did not vary as a function of postconceptional age. These results indicate that plasma UfMg is kept constant at different gestational ages despite variations in total plasma Mg; furthermore, no functional immaturity is present for renal tubular reabsorption of Mg, even in very low birth weight infants.
由于直到最近测量血浆镁的可扩散部分（超滤镁，UfMg）仍存在困难，新生儿期镁（Mg）的肾脏处理尚未得到全面研究。在本研究中，采用这种方法评估了84例不同孕龄（26 - 42周）、体重（720 - 4830克）和出生后年龄（1 - 72天）的新生儿的镁稳态。极早产儿（孕龄小于35周）的血浆镁值显著高于成熟新生儿。血浆镁与孕龄、体重、血浆总蛋白和血浆钙呈负相关，与血浆钾呈正相关。逐步多元回归分析显示，孕龄是导致血浆镁变化的唯一因素。早产儿和足月儿的超滤镁血浆值相同，但以总血浆镁的分数表示（UfMg/Mg）时，极早产儿的该值显著较低。镁的分数排泄以及尿镁与尿肌酐的比值并不随孕龄而变化。这些结果表明，尽管总血浆镁存在变化，但不同胎龄时血浆超滤镁保持恒定；此外，即使是极低出生体重儿，肾小管对镁的重吸收也不存在功能不成熟的情况。
