Agrawal V, Agarwal M, Joshi Shashank R, Ghosh A K
Department of Internal Medicine, William Beaumont Hospital, Royal Oak, MI, USA.
J Assoc Physicians India. 2008 Dec;56:956-64.
Total body water and tonicity is tightly regulated by renal action of antidiuretic hormone (ADH), reninangiotensin-aldosterone system, norepinephrine and by the thirst mechanism. Abnormalities in water balance are manifested as sodium disturbances--hyponatremia and hypernatremia. Hyponatremia ([Na+ < 136 meq/ l]) is a common abnormality in hospitalized patients and is associated with increased morbidity and mortality. A common cause of hyponatremia is impaired renal water excretion either due to low extracellular fluid volume or inappropriate secretion of ADH. Clinical assessment of total body water and urine studies help in determining cause and guiding treatment of hyponatremia. Acute and severe hyponatremia cause neurological symptoms necessitating rapid correction with hypertonic saline. Careful administration and monitoring of serum [Na+] is required to avoid overcorrection and complication of osmotic demyelination. Vasopressin receptor antagonists are being evaluated in management of euvolemic and hypervolemic hyponatremia. Hypematremia ([Na+] > 145 meq/l) is caused by primary water deficit (with or without Na+ loss) and commonly occurs from inadequate access to water or impaired thirst mechanism. Assessment of the clinical circumstances and urine studies help determine the etiology, while management of hypernatremia involves fluid resuscitation and avoiding neurological complications from hypernatremia or its correction. Frequent monitoring of [Na+] is of paramount importance in the treatment of sodium disorders that overcomes the limitations of prediction equations.
总体水和张力受抗利尿激素（ADH）、肾素 - 血管紧张素 - 醛固酮系统、去甲肾上腺素的肾脏作用以及口渴机制的严格调节。水平衡异常表现为钠紊乱——低钠血症和高钠血症。低钠血症（[Na⁺]<136毫当量/升）是住院患者常见的异常情况，与发病率和死亡率增加相关。低钠血症的常见原因是由于细胞外液量低或ADH分泌不当导致肾排水受损。对总体水的临床评估和尿液检查有助于确定低钠血症的病因并指导治疗。急性和严重低钠血症会引起神经症状，需要用高渗盐水迅速纠正。需要仔细给予和监测血清[Na⁺]，以避免过度纠正和渗透性脱髓鞘并发症。血管加压素受体拮抗剂正在用于等容性和高容性低钠血症的治疗评估。高钠血症（[Na⁺]>145毫当量/升）由原发性水缺乏（伴有或不伴有Na⁺丢失）引起，通常因饮水不足或口渴机制受损而发生。对临床情况和尿液检查的评估有助于确定病因，而高钠血症的治疗包括液体复苏并避免高钠血症或其纠正引起的神经并发症。在治疗钠紊乱时，频繁监测[Na⁺]至关重要，这克服了预测方程的局限性。
