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Diuretics are a large group of medications used to treat various conditions, such as hypertension, chronic heart failure, severe lung edema, and others. 

In essence, the primary function of all diuretics is to eliminate excess fluid from the body by increasing urine volume. However, different diuretics have very different potential dosages, contraindications, and side effects. Here are some of the most important facts regarding types of diuretics, their properties, and possible side effects.

Diuretics: Mechanism Of Action

Sodium is the most troubling electrolyte for patients with hypertension, as one atom of sodium binds four molecules of water. Therefore, the more sodium is in the organism, the more water is in the patient's body, and this leads to increased blood volume and consequently high blood pressure. The mechanism by which almost all diuretics manage to eliminate excess sodium is a bit complex, but it is enough to say that they lower the reabsorption of sodium in the kidneys. This gives sodium (and water) the chance to exit through the urine.

Blockage of sodium reabsorption is commonly joined with the excess elimination of another electrolyte — potassium, which can contribute to some side effects. Not all diuretics eliminate potassium, as we will see further in the text.

Thiazide Diuretics

Doctors widely prescribe Thiazide diuretics for the treatment of hypertension. They are considered medium strength diuretics because they eliminate a moderate amount of sodium from the organism. Additionally, the potassium elimination is not very pronounced with these diuretics, although it is possible if Thiazide diuretics are used in high dosages for a prolonged time. One of the most commonly used diuretics from this group is hydrochlorothiazide.

Loop Diuretics

Loop diuretics act on a different part of the renal tubules and have a slightly different mechanism of action than thiazide diuretics, but the result is the same — elimination of excess water. Loop diuretics are very potent and fast acting, and they are commonly used intravenously to lower the blood pressure quickly when it reaches extreme levels. Doctors also prescribe them to eliminate fluid during lung edema and in patients with heart failure. Long-term use of these diuretics requires taking potassium supplements, as these diuretics eliminate potassium very intensively.

Potassium-Sparing Diuretics

These diuretics are very popular because they do not eliminate potassium from the body, but are still effective in lowering blood pressure. They are the weakest diuretics, but in mild forms of hypertension, they can be the best option.

Side Effects Of Diuretics

Diuretics are actually considered very safe, if used in recommended dosages. They do not affect receptors in the body, other than those in the kidneys. The most common side effect is a potassium deficiency, which happens only with certain types of diuretics. However, this can be a very serious side effect. Potassium is one of the most important electrolytes in the body, and its blood concentration must be kept very precise. A potassium deficiency can produce severe arrhythmias and heart palpitations.

Some persons have noticed weight fluctuations while using diuretics. Weight loss is more common, because of the water elimination, but some persons also report weight gain. There is not much scientific data about this phenomenon, but changes in potassium metabolism may be involved in this process. Namely, the changes in potassium levels affect glucose metabolism, which can contribute to unexpected fluctuations in body weight.

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