Diuretics are medications that increase your urine output by altering the way your kidneys use the mineral sodium. Your doctor may prescribe a medication in this class if you have high blood pressure, heart failure or a type of swelling called edema. People who take diuretics typically need to avoid increasing their sodium consumption.
Sodium Basics
Your body needs a certain amount of sodium to maintain basic aspects of your health such as your blood pressure and nerve and muscle function. For this reason, when sodium in your bloodstream passes to your kidneys, a certain percentage of it is filtered out and reabsorbed by your body instead of getting excreted in your urine. Your body also needs to maintain a balance between your sodium levels and your water levels. If you have too little sodium in your body relative to your water levels, you can develop a potentially life-threatening condition called hyponatremia.
Effects of Diuretics
Most diuretics achieve their urine-increasing effects by directly altering the percentage of sodium that is filtered in your kidneys and reabsorbed by your body. Medications called thiazide diuretics produce relatively minor effects by inhibiting an area of your kidneys that normally filters out roughly 5 percent of the sodium in your blood. Medications called loop diuretics produce a more powerful effect by inhibiting an area of your kidneys that normally filters out roughly 25 percent of the sodium in your blood. Medications called potassium-sparing diuretics indirectly alter your sodium reabsorption by altering your body's use of a hormone called aldosterone. Weak diuretics called carbonic anhydrase inhibitors achieve their effects by altering your body's use of a substance called bicarbonate.
Sodium Intake
Ideally, diuretics achieve their beneficial effects with minimal disturbances in your normal sodium levels. For this reason, doctors most frequently prescribe thiazide diuretics, which increase your urine flow while triggering only small changes in sodium handling. In people with high blood pressure, the effectiveness of diuretics is typically enhanced by adoption of a low-sodium diet. In people with heart problems, diuretics help reduce edema by lowering the volume of blood inside blood vessels. Consumption of sodium can increase blood volume and offset this positive effect.
Considerations
If diuretics use triggers the onset of hyponatremia, your doctor may need to use an intravenous, or IV, sodium solution to raise your raise blood levels of the mineral back to normal. Other methods used to treat hyponatremia include restriction of your water intake and adjustment of your diuretic dosages. In addition to high blood pressure and heart failure, conditions associated with high sodium intake include kidney disease, stroke and other forms of heart disease. Consult your doctor for more information on diuretic use and the potential effects of increased sodium intake.
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