Blood pressure is the force that your blood exerts on the walls of your arteries as it flows through them. Hypertension, or high blood pressure, is characterized by a blood pressure of 140/90 mm Hg or higher. The most commonly prescribed medication to lower blood pressure is a class of drugs called diuretics. While diuretics are often effective in treating hypertension, they are not without side effects.
Physiology
Many people have high blood pressure as a result of their body retaining too much water. When your body contains excess water, the volume of your blood increases. Increased blood volume results in an increase in the pressure that blood exerts on the walls of your arteries, often to leading to hypertension. Diuretics work by stimulating the body to release excess amounts of water through your urine. The release of water helps to lower your blood volume, which in turn can decrease your blood pressure.
Types of Diuretics
Different types of diuretics are available to help treat hypertension. Thiazide diuretics help reduce blood pressure by stimulating the body to eliminate sodium and water. Thiazide diuretics also dilate the blood vessels, which can also reduce blood pressure, according to the Texas Heart Institute. Potassium-sparing diuretics reduce the amount of water in your body but allow the body to retain potassium. Loop-acting diuretics work by triggering the kidneys to produce more urine, which can help you reduce the amount of water in your body.
Abnormal Potassium Levels
Because potassium is dissolved in water in your body, potassium is lost with water. When thiazide diuretics stimulate your body to release excess water, you lose potassium from your blood as well. This can lead to low potassium levels, called hypokalemia. Potassium-sparing diuretics stimulate your body to release sodium and water but retain potassium. Because of this, the electrolyte and water balance is disrupted, leading to high levels of potassium in your blood, a condition called hyperkalemia.
Complications
Abnormal blood potassium levels can disrupt the electrical system in your heart, leading to irregular heartbeat, or arrhythmia. Arrhythmias may be characterized by an unusually fast heartbeat, or tachycardia, or an unusually slow heartbeat, or bradycardia. Arrhythmias put stress on the heart, and if left untreated, severe arrhythmias can lead to heart failure or stroke. In addition to abnormal heart beat, hypokalemia can cause physical symptoms such as constipation, fatigue, muscle weakness and spasms. Hyperkalemia manifests causes nausea and a weak or absent pulse, according to Medline Plus.
Considerations
If you are taking diuretics, it may be beneficial to get regular blood screenings so that you can monitor your potassium levels. Monitoring your potassium levels help you take necessary steps to correct potassium levels should they fall too high or too low. If your potassium levels fall too low, it may be necessary to increase your dietary potassium intake or begin taking potassium supplements. If your potassium levels get too high as a result of a potassium-sparing diuretic, it may be necessary to switch to a different hypertension medication.
