Fluids and Electrolytes: Sodium. 
This week, we tackle sodium. Let us talk a little bit about sodium. Sodium is the primary extracellular electrolyte This means it is the primary electrolyte outside of cells. So that gives us a lot of range. For this sodium debate. It can be in the interstitial spaces and in the bloodstream. Sodium maintains our osmotic pressure. Osmotic pressure is what pulls fluid back and forth. Sodium also helps to maintain our acid-base balance and helps maintain nerve conduction impulses. If the sodium level decreases, that will stimulate aldosterone secretion. If the sodium level increases, it will suppress aldosterone secretion. aldosterone helps us to regulate water.