Body and biology
What Is HMG-CoA Reductase? How Statins Work, Explained
HMG-CoA Reductase · say it: aych-em-jee koh-AY reh-DUK-tayzAlso written: HMG-CoA reductase inhibitor, HMG-CoA reductase inhibitors, statin enzyme
Short answer
HMG-CoA reductase is the liver enzyme that controls how much cholesterol the body makes; statins work by blocking it.
What it means
HMG-CoA reductase is an enzyme, mainly in the liver, that carries out a key step in the body's own production of cholesterol. Medicines that block it are called HMG-CoA reductase inhibitors, better known as statins. Examples include atorvastatin, simvastatin and rosuvastatin. By slowing this enzyme, the liver makes less cholesterol and removes more LDL ('bad') cholesterol from the blood.
Labels use the long name in the 'Mechanism of action' section and often in the drug-class description, such as 'an HMG-CoA reductase inhibitor (statin)'. The same labels warn about muscle problems (myopathy and the rare rhabdomyolysis), liver tests and interactions, especially with some CYP3A inhibitors for certain statins.
HMG-CoA reductase is a normal enzyme, not a test result. Seeing it on a label simply tells you the medicine is a statin.
Where you may see it
- Statin labels under 'Description' and 'Mechanism of action'
- Pharmacology sections of leaflets
- Pharmacist medication reviews
📄 How it looks on a report
Atorvastatin is a selective, competitive inhibitor of HMG-CoA reductase.
🙅 What it does not mean
- It is not a condition or an abnormal result.
- Blocking the enzyme does not stop cholesterol production completely; it lowers it.
- Muscle aches on a statin are not always caused by the statin, but they should be reported.
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “HMG-CoA Reductase”
Plain-English explanations of each medicine, from its official FDA label.
- Atorvastatin
a statin, a cholesterol-lowering medicine of the HMG-CoA reductase inhibitor type
- Simvastatin
a cholesterol-lowering medicine of the HMG-CoA reductase inhibitor type (often called a statin)
🔗 Read more from trusted sources
- “HMG-CoA Reductase” on MedlinePlus ↗
US National Library of Medicine
- NCI Dictionary definition ↗
US National Cancer Institute: “hmg coa reductase inhibitor”
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.