Chin Med J (Taipei) 1998;61:S178.

Clinical Practice on Electrolyte Disorders: Sodium Disorders

Wu-Chang Yang, M.D.

Division of Nephrology, Department of Medicine, Veterans General Hospital-Taipei, and National Yang-Ming University

Abstract

Abnormal plasma sodium concentration results from abnormal water intake or water output. Treatment is guided by determing the pathogenic mechanism. The incidence and prevalence of hyponatremia among hospitalized patients were ~1.0% and ~2.5%, respectively. In most instances, hyponatremia is caused by inappropriate concentration of urine because of either appropriate or inappropriate antidiuretic hormone (ADH) secretion. The determination of appropriateness of ADH secretion requires the assessment of effective arterial volume. The clinical importance of hyponatremia is because: (1) acute severe hyponatremia can cause substantial morbidity and mortality; (2) mild hyponatremia can progress to more dangerous levels during management of other disorders; and (3) overly rapid correction of chronic hyponatremia can produce severe neurological deficits and death.

The prevalence of hypernatremia in hospitalized patients is ~0.5 ~2.0%. The key aspect in the approach to hypernatremia is determination of the mechanism responsible for impaired water intake. Various mechanisms of abnormal water loss can be determined from measurement of urine osmolality. Hospital-acquired hypernatremia was primarily iatrogenic, resulting from inadequate and inappropriate prescription of fluids to patients with predictably increased water losses and impaired thirst or restricted free water intake or both. Mortality was 41% for hypernatremic patients, but hypernatremia per se has contributed to mortality in only 16% of the patients.

In conclusion, treatment of sodium disorder should be guided by determining the pathogenic mechanisms of water imbalance. Case presentation will be provided to explain its pathophysiologic approach.

[Chin Med J (Taipei) 1998;61:S178.]