Diuretics - Effects on the Body
Effects on the Body
There are three main classes of diuretics: loop diuretics, potassium-sparing diuretics, and thiazide diuretics. The main function of diuretics is to increase the amount of sodium and fluids excreted by the kidneys.
Kidneys and Electrolytes
The kidneys are the urine-producing organs of the body. They act as filters for body fluids, sifting out waste products and keeping important body chemicals called electrolytesCharged atoms such as sodium, potassium, chloride, calcium, and magnesium that conduct electrical impulses in the body, and therefore are essential in nerve, muscle, and heart function. at steady levels. As the Kidney Learning System Web site points out, another key function of these "powerful chemical factories" is to "remove drugs from the body."
Sodium, potassium, chloride, calcium, and magnesium are all examples of electrolytes. These chemicals are present in the body's fluids and help move nutrients into cells and wastes out of them. Nerve, muscle, and heart functions depend on proper levels of electrolytes in the body. The use of diuretics, however, can trigger electrolyte imbalances. This occurs because diuretics increase the amount of urine the body releases. Sodium, potassium, and other electrolytes can be removed from the body along with the urine.
The kidneys work to keep electrolyte concentrations in the blood at an even level. However, swings in body fluid chemicals do occur. Improper levels of electrolytes can cause a variety of symptoms, including confusion, fainting, dizziness, and headache.
Reducing Fluid Levels
In general, diuretics work by encouraging the loss of sodium and fluid from the body. This is the key to their effectiveness in treating high blood pressure and congestive heart failure.
People who suffer from long-term high blood pressure are said to have hypertension. Hypertension occurs when the force of blood against the blood vessel walls increases. This condition may be treated with diuretics from all three classes. Those used most often include thiazides such as chlorothiazide and hydrochlorothiazide; the potassium-sparing diuretic spironolactone; and the loop diuretic furosemide. Diuretics relieve hypertension by flushing excess water and sodium from the body. Lower fluid levels decrease the pressure on blood vessels and help improve blood circulation, resulting in lower blood pressure.
Congestive heart failure occurs when the pumping ability of the heart is impaired. Loop diuretics such as furosemide are most frequently prescribed to reduce the edema that results from congestive heart failure. Thiazide and potassium-sparing diuretics may also be prescribed.
Doctors also prescribe diuretics for other conditions that cause fluid retention, including certain types of diabetesA serious disorder that causes problems with the normal breakdown of sugars in the body. and various diseases of the kidneys and the liver. Water retention related to menstruation is usually relieved with over-the-counter diuretics containing Pamabrom (Pamprin).
Among the more common side effects of diuretic use are nausea, dizziness, skin rashes, sensitivity to sunlight, high blood sugar levels, and an inability to control urination. Less common side effects associated with diuretic use include hearing loss, lowered red blood cell or white blood cell levels, and inflammation of the pancreas, a gland vital to digestion.
The Loop Diuretics and Their Action on the Kidneys
Each kidney consists of about 1 million nephronsTiny working units of the kidney; each kidney has more than a million nephrons. held in place by supporting tissue. Nephrons are the tiny filtering units of the kidney. These structures are responsible for moving fluids and waste out of the bloodstream, resulting in urine formation. Loop diuretics take their name from the part of the kidney upon which they workâthe loop of Henle. The loop of Henle is a branch within each nephron where sodium and potassium are reabsorbed back into the bloodstream instead of being filtered into the urine. Loop diuretics inhibit this action and promote excretion of the sodium and potassium instead, along with calcium, magnesium, and, of course, water. Loop diuretics are considered the most powerful of all diuretics. Bumetanide (Bumex), furosemide (Lasix), and torsemide (Demadex) are all loop diuretics.
The Potassium Balancing Act and Other Things to Know about Diuretics
Two other classes of diuretics are the thiazides and the potassium-sparing diuretics. Thiazide diuretics such as chlorothiazide and hydrochlorothiazide work by blocking sodium reabsorption by the kidneys. They are "potassium-depleting" diuretics, meaning that they cause a loss of potassium from the body. This condition is known as hypokalemiaA loss of potassium in the body.. This loss may be reversed by eating potassium-rich foods, such as bananas, or by taking potassium supplements. Signs of hypokalemia include a rapid or irregular heartbeat, fatigue, weakness, mood swings, muscle cramps, nausea, vomiting, a dry mouth, and persistent thirst.
The diuretics amiloride, spironolactone, and triamterene are known as "potassiumsparing" diuretics. This type of diuretic is used commonly in the treatment of congestive heart failure. Their use may cause hyperkalemiaA dangerous build-up of excess potassium in the body., a condition where there is too much potassium in the body. Signs of hyperkalemia include an irregular heartbeat, tiredness, weakness, difficulty breathing, numbness, a tingling sensation in the hands or feet, anxiety, and difficulty concentrating.
Sometimes, potassium-sparing diuretics are used in conjunction with thiazide diuretics to keep potassium levels in the user's body stable. One drug known by the brand name Dyazide is a good example of a combination-type diuretic. It contains hydrochlorothiazide (a thiazide diuretic that causes a loss of potassium in the body) and triamterene (a diuretic that helps the body retain potassium).
Other Risks:
The use of diuretics can be especially risky among pregnant women, people with compromised immune systems, and individuals with certain drug allergies. Physicians must be made aware of a patient's complete medical history before they can prescribe diuretics safely. Individuals who take diuretics for more than six months at a time run the risk of developing chemical imbalances that can result in serious side effects.
Magnesium deficiency may occur with long-term use of the loop and thiazide diuretics. Symptoms include nausea and vomiting, muscle cramps, weakness (especially when exercising), insomniaDifficulty falling asleep or an inability to sleep., an irregular heartbeat, and difficulty sleeping. Calcium deficiency is a possible side effect of both loop and potassium-sparing diuretics. Signs of insufficient calcium in the body include a rapid heartbeat, muscle cramps, bone thinning, tooth decay, and difficulty sleeping.
Dehydration
Diuretic use in sports is usually prompted by the belief that a lower weight will improve athletic performance. However, the side effects experienced from long-term diuretic abuse typically offset any temporary gains in ability.
The main risk of diuretic abuse is severe dehydration. This is of special concern to athletes who might take the drug to "make weight" for sporting events or to improve performance. People exercising or participating in athletic competition are already at risk for dehydration because they are losing large amounts of fluids and electrolytes in their sweat. Diuretics can speed up this process.
Patients on doctor-prescribed diuretics must take extra precautions when exercising. These include: 1) drinking adequate amounts of water, sports drinks, or other non-caffeinated fluids; 2) wearing loose and comfortable clothing; 3) setting aside time for regular rest periods; and 4) watching for signs of heat exhaustionA condition that results from physical exertion in extreme heat; symptoms range from clammy and cool skin, tiredness, nausea, weakness, confusion, and vision problems to a possible loss of consciousness..
It is absolutely essential that a patient remain in regular touch with the prescribing doctor throughout the course of diuretic therapy.
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