What is the first-line treatment for SIADH if sodium levels exceed 120 mEq/L?

Fluid restriction is considered the first-line treatment for Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH) when sodium levels exceed 120 mEq/L. This approach is effective because reducing fluid intake helps to decrease the total body water, which in turn can increase serum sodium levels. SIADH is characterized by an inappropriate retention of water due to excess ADH secretion, leading to dilutional hyponatremia.

By limiting fluid intake, the body can gradually achieve a more balanced ratio of electrolytes, allowing sodium levels to rise as excess body water is eliminated naturally. This strategy is particularly suitable for patients whose sodium levels are not critically low, as excessive sodium correction can have adverse neurological consequences, such as osmotic demyelination syndrome.

Other treatments, such as administering hypertonic saline or using diuretics, may be indicated in specific situations, particularly for patients with more severe hyponatremia or symptoms of cerebral edema. However, fluid restriction remains the primary and safest initial intervention when sodium levels are over 120 mEq/L.