If you have high cholesterol that can't be managed with lifestyle modifications like a low-fat diet and increased exercise, your doctor may prescribe a statin drug. These drugs reduce LDL, or "bad" cholesterol, while increasing HDL, or "good" cholesterol. Because they are metabolized by the liver, statins can be associated with liver damage. This manifests as an elevation in certain liver enzymes, a sign that liver cells have died and released their contents. Because liver damage can occur without any symptoms, your doctor routinely checks the levels of these enzymes to watch for early signs of damage.
Statins
Statins, also known as HMG-CoA reductase inhibitors, are a class of drugs that includes rosuvastatin, or Crestor, and atorvastatin, or Lipitor. Other members include simvastatin, also known as Zocor, fluvastatoin and pravastatin. These drugs inhibit the production of cholesterol by the liver. The result is a reduction in LDL cholesterol, a modest decrease in triglyceride levels and a small increase in HDL, the good cholesterol. Statins are a first-line therapy in the management of elevated cholesterol. Doctors also use them in patients who have suffered a heart attack, even if cholesterol levels are normal.
Liver Effects
Once the drug is absorbed by your gastrointestinal tract, it passes to the liver, which converts it to an active substance. It is here, in the liver, where statins exert their effect. The liver enzyme HMG-CoA is involved in the synthesis of cholesterol. By inhibiting this enzyme, statins are able to block the production of cholesterol, greatly reducing the amount that your body produces. This helps lower the cholesterol levels in your blood. Statins are also able to increase your liver's removal of LDL cholesterol from your blood, which further helps lower cholesterol.
Liver Enzymes
Your liver produces many enzymes involved in metabolism. Among these is the class of enzymes known as aminotransferases. These enzymes include alanine transaminase, or ALT, and aspartate aminotransferase, or AST. ALT and AST help convert the proteins in your food to substances your body uses for growth and repair. The normal range for these enzymes is between 10 and 40 U/L.
Elevated Enzymes
Elevations in these enzymes occur in some patients taking statins. This is often brief and is usually not associated with liver damage. If the elevation is monitored and stable, your doctor may choose to continue therapy with the medication. However, levels exceeding three times normal, equivalent to 120 U/L or higher, may indicate liver toxicity. Symptoms such as loss of appetite and fatigue may occur and warrant immediate discontinuation of treatment. For further information, talk to your doctor.
Considerations
Elevated liver enzymes in conjunction with statin use is more common in patients with pre-existing liver disease or a history of alcohol abuse. Also, certain classes of individuals, including Asians and the elderly, are known to be more sensitive to the effects of statins, and reduced dosage may be indicated. If your doctor prescribes a statin for you, liver enzymes are usually checked before administering the drug, again after one or two months, and then every six to 12 months if enzymes are normal. This protocol may vary depending on the treatment center.
References
- "Basic and Clinical Pharmacology, 10th Edition; Bertram G. Katzung; M.D., Ph.D.; 2009
- "Maxwell Quick Medical Reference"; Robert W. Maxwell; 2006
