Diuretics work with your kidneys to excrete sodium from your system via your urine. In turn, the sodium takes water from your blood, and the water is also excreted. This reduction in fluid puts less pressure on the walls of your blood vessels and helps reduce pressure in your arteries. Diuretics come in three types: loop diuretics, such as torsemide and furosemide; thiazides, such as hydrochlorothiazide and indapamide; and potassium-sparing, such as amiloride and spironolactone.

Uses of Diuretics

Three main reasons are given for using diuretics. The first is to rid the body of excess fluid, also called edema, that accumulates in interstitial places in the body and increases the extracellular spaces. The second is to lower increased arterial pressure, seen in hypertension 1. The third is to treat congestive heart failure, which is seen when one side of the heart fails to pump as strongly as the other -- creating pressure from a backup of blood. This blood is forced into the interstitial tissues, causing edema.

Sodium

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Sodium, sodium chloride or salt is crucial to the maintenance of life. Sodium is a mineral that experiences tight regulations within your body. Sodium and chloride are electrically charged ions that exist in the fluid outside the cells in the extracellular spaces. This fluid also contains blood plasma. The balance of fluid within your cells depends on the amount of sodium that is outside your cells. Any change in this balance, such as with diuretics, changes the amount of fluid that you hold in your body.

Potassium

Potassium is another mineral that acts as an electrolyte in your body. Potassium is an electrically charged ion that sits mainly inside the cell. Thirty times more potassium is inside the cell structure than outside in the extracellular spaces. The balance between potassium on the inside of the cell and sodium on the outside of the cell is referred to as the membrane potential and provides 30 to 40 percent of your resting energy.

Interaction of Diuretics

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The filtering of blood through your kidneys maintains the chemical balance of the blood, including the potassium and sodium levels. Any necessary fluids that do not need to be excreted in the urine are reabsorbed. Diuretics cause the kidneys to put more sodium into the blood, thus pulling more fluid out of the interstitial tissues and excreting more fluid into the urine. Alongside the sodium and fluid, potassium is also excreted into the urine, which may lead to low potassium levels in your body.