All issues > Volume 50(5); 2007

Review Article

Korean J Pediatr. 2007;50(5):430-435. Published online May 15, 2007.

Pathophysiology and management of disorders in water metabolism

Dong Un DU Kim¹

¹Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea

Correspondence Dong Un DU Kim ,Email: dukim@catholic.ac.kr

Abstract

Even though we drink and excrete water without recognition, the amount and the composition of body fluid remain constant everyday. Maintenance of a normal osmolality is under the control of water balance which is regulated by vasopressin despite sodium concentration is the dominant determinant of plasma osmolality. The increased plasma osmolality (hypernatremia) can be normalized by the concentration of urine, which is the other way of gaining free water than drinking water, while the low plasma osmolality (hyponatremia) can be normalized by the dilution of urine which is the only regulated way of free water excretion. On the other hand, volume status depends on the control of sodium balance which is regulated mainly by renin-angiotensin-aldosterone system, through which volume depletion can be restored by enhancing sodium retention and concomitant water reabsorption. This review focuses on the urine concentration and dilution mechanism mediated by vasopressin and the associated disorders; diabetes insipidus and syndrome of inappropriate antidiuretic hormone secretion.

Keywords :Osmolality, Volume, Urine concentration and dilution, Diabetes insipidus, Syndrome of inappropriate antidiuretic hormone secretion