摘要: Hyponatremia is a common electrolyte disorder in children. It generally defined as plasma sodium of less than 135 mmol/L. Sodium homeostasis essential for maintaining intravascular volume and tightly linked to water balance. Plasma regulated mainly by the secretion an antidiuretic hormone (ADH) thirst mechanism. ADH synthesized hypothalamus stored posterior hypophysis. binds V2 receptors distal nephron induces translocation aquaporin channels membrane retain water. There are two main types involved control body balance- osmoreceptors baroreceptors. Osmoreceptors reside respond changes extracellular fluid osmolality. Baroreceptors mechanoreceptors that sense blood pressure vessel wall. Response reflexes from baroreceptors influence sympathetic outflow, tonus, cardiac output. An increase 1% osmolality may cause levels, while threshold higher. However, significant hypotension more potent stimulus increased The pediatric hyponatremia abundance free This occur hypovolemic children with low ECF volume, normovolemic patients inappropriately secretion, also hypervolemic individuals decreased effective circulating appropriately levels. Proper understanding pathophysiology hyponatremic states establishing correct diagnosis appropriate therapy.