Diuretics

Diuretics are a group of medications typically used to treat high blood pressure or congestive heart disease, but they have also been abused by athletes to gain a competitive advantage or to cover up evidence of the use of other performance enhancers.

A diuretic is anything that causes a person to produce more urine from the kidneys. There are many different kinds of diuretics, and they act on the kidney in slightly different ways. Medications such as hydrochlorothiazide (HCTZ) or furosemide affect the small blood vessels in the kidney. This changes how blood flows through the kidney and causes more free water to be filtered from the blood. Osmotic diuretics such as mannitol work in a different way. Free water is drawn out of the blood by the kidneys by way of elaborate concentration gradients, producing very dilute urine very quickly.

As urine is produced, electrolytes and minerals are lost in the urine. In addition, toxins and chemicals are cleared from the body. The athlete also loses free water from the blood. Diuretics are commonly used in medicine to treat high blood pressure or congestive heart failure. During this treatment, electrolytes such as potassium and [Page 377]sodium are carefully monitored and sometimes have to be supplemented.

Diuretics are used for therapeutic purposes and can be abused for enhancing athletic performance. Athletes may surreptitiously use diuretics for several reasons. Wrestlers and boxers use them to rapidly lose weight so they can compete in a specific weight class. Bodybuilders use them before the competition to dehydrate themselves and enhance muscle definition. Diuretics are sometimes used by athletes who are trying to cover up the use of other performance-enhancing substances and beat a drug test. This is one of the reasons why drug testing in sports includes tests for the presence of diuretics. The presence of some of these diuretics in a drug test is considered as grounds for disqualification unless a documented medical reason for using the diuretic is presented to the competition committee prior to the event.

There is a process, however, to ensure that an athlete is able to use a substance that could be otherwise considered a doping agent, such as insulin or albuterol, in a medically responsible way to treat an illness or condition. A Therapeutic Use Exemption is not valid if an athlete's urine contains a diuretic in association with threshold or subthreshold levels of a prohibited substance.

There can be significant side effects from the use of diuretics. Rapid shifts in electrolytes can cause deadly heart arrhythmias or seizure. They can cause dehydration and symptoms such as dizziness, fatigue, confusion, headache, or syncope (passing out). In addition, electrolyte abnormalities and dehydration can contribute to muscle cramping and worsening of asthma symptoms. Dehydration and diuretic use can contribute to kidney damage and renal failure.