Creatine is a dietary supplement that is often used to improve athletic performance. Excessive use of creatine can strain the kidneys and cause kidney damage. Individuals should follow proper dosing recommendations for creatine and consult a physician prior to taking supplements. Individuals who currently take creatine and have kidney problems should discontinue use of creatine to prevent further kidney damage.

Creatine
Creatine is an amino acid that is synthesized in the kidneys and liver and supports muscle growth and contraction, according to Peace Health. Creatine is naturally available in fish and meat and is also marketed to athletes as a performance-enhancing supplement. According to the Mayo Clinic, the most popular creatine supplement is creatine monohydrate. Prolonged use or high doses of creatine may contribute to kidney damage.

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Kidneys and Creatinine
Kidneys remove waste from the body, help form red blood cells and help regulate blood pressure. Creatinine is a chemical waste product of creatine. It is usually filtered out through the kidneys and excreted in the urine. High levels of creatinine in the blood can be caused by high doses of creatine and may be a sign of kidney damage and the inability of the kidneys to filter out creatinine.

MedlinePlus says kidney problems that are associated with high creatinine levels include acute tubular necrosis, diabetic nephropathy, glomerulonephritis or pyelonephritis, all of which can lead to chronic kidney disease (CKD) or kidney failure. CKD and kidney failure can result in seizures, coma and, ultimately, death. Individuals with either condition may need dialysis, a regular treatment that cleans the blood, or a kidney transplant.

Lab Values
According to the Mayo Clinic, normal blood creatinine is 0.6 to 1.2 mg/dL. Men usually have higher creatinine levels than women because creatinine increases with muscle mass. High creatinine can be caused by dehydration, certain medications and creatine supplements.

Dosing
The University of Maryland Medical Center says the risk of kidney damage is greater when high doses of creatine supplements are taken. The Mayo Clinic does not advise taking more creatine than is recommended by manufacturers. A normal loading dose for an athlete prior to an athletic event is 5g, four times a day for a week. A maintenance dose for athletes is 2 to 5g per day.

Warnings and Considerations
According to MedlinePlus, possible side effects of creatine supplements include upset stomach, loss of appetite, diarrhea, nausea, muscle cramps, heat intolerance, fever, dehydration, reduced blood volume, electrolyte imbalances, increased thirst, headache, anxiety, irritability, aggression, nervousness, sleepiness, depression, abnormal heart rhythm, fainting or dizziness, blood clots in the legs, seizure and swollen limbs.

Creatine supplements are not regulated by the Food and Drug Administration. Many of the health and performance claims for creatine have not been scientifically substantiated. Peace Health advises that creatine should only be taken after consultation with a doctor or pharmacist. Creatine may not be appropriate for pregnant or breastfeeding women and children. It should not be taken by people with kidney or liver disease due to the risk of further kidney damage and altered liver function.

Creatine and Growth Hormone

Creatine, a naturally occurring protein, plays an essential role in muscle development, conversion of fat to energy and possibly brain function and maintenance of the immune system. Importantly for athletes, creatine is reported to enhance physical performance by stimulating the production of human growth hormone (HGH).
The pituitary gland, a small organ at the base of the brain, produces HGH along with other hormones. HGH regulates muscle development, organ growth and bone length, or height. The pituitary gland continues to produce HGH throughout life, but it releases HGH at slower rates as we age.
Almost all creatine in the body is concentrated in the muscles, and the remaining 5 percent is found largely in organs with high-energy needs such as the heart, brain and testes. Reduced HGH levels gradually result in typical signs of aging: muscle loss, higher fat-to-muscle ratio and bone loss. Skin sags as it loses elasticity and tone. Illnesses increase as the immune system loses potency.
HGH supplementation can reverse these signs of aging. However, expense and tight regulation make HGH treatments impractical. Anaerobic exercise, such as weightlifting, or intense, sustained aerobic exercise, such as long-distance running, can boost HGH production. Creatine, obtained either naturally in the diet or through supplements, can also increase HGH.

Creatine supplementation stimulates release of HGH from the pituitary, mimicking HGH replacement therapy. Effects of continued creatine supplementation include improved mood, regeneration of bone and muscle mass, reduced body fat and enhanced stamina.
Because it improves muscle mass and endurance, creatine supplementation is popular among athletes. Other uses of creatine are being explored, such as a treatment for heart disease, muscular dystrophy, Alzheimer's disease and Lou Gehrig's disease.
Meat, poultry and fish are natural sources of creatine. The liver and kidneys also manufacture creatine using specific amino acids. Additionally, creatine supplements are available in powder or tablet form. Most people receive an average of 2 g of creatine per day in their diet.

Although creatine is a naturally occurring protein, supplementation is associated with side effects. Creatine supplements are associated with water retention, weight gain, diarrhea, nausea, vomiting, cramping, gastrointestinal problems, muscle pain and high blood pressure.
Creatine is considered a dietary supplement, not a drug, and is not regulated by the Food and Drug Administration. Quality varies among products, and harmful additives or contaminants are not monitored or controlled.
Consistent improvement in physical performance has not been proven in scientific research. Some studies have shown creatine supplements slightly boost performance in sports such as weightlifting and sprinting that require short energy bursts. Results vary, however, and not everyone experiences the same level of benefit. Some people don't respond to creatine at all.
As an untested treatment, creatine supplementation has no standard dose and the long-term risks are unknown. Creatine supplements are not recommended for people with diabetes or kidney or liver disease.