General medical words
What Is a Poor Metabolizer? Gene Test Results Explained
Poor Metabolizer · say it: poor meh-TAB-uh-ly-zerAlso written: poor metaboliser, PM, slow metabolizer, poor metabolizer phenotype
Short answer
A poor metabolizer is a person whose genes make a particular drug-processing enzyme work very slowly, which can change how some medicines act.
What it means
Your genes affect how well certain liver enzymes, such as CYP2D6 and CYP2C19, work. A poor metabolizer has gene versions that make one of these enzymes work very slowly or hardly at all. Other categories include intermediate, normal (extensive), rapid and ultrarapid metabolizers. Being a poor metabolizer applies to one enzyme at a time, not to all medicines.
Labels mention poor metabolizers because the effect depends on the medicine. If the enzyme normally clears an active medicine, a poor metabolizer may build up higher levels and get more side effects. If the enzyme is needed to activate a prodrug, such as clopidogrel (CYP2C19) or codeine (CYP2D6), a poor metabolizer may get less benefit. The label may advise a different medicine or dose.
A poor metabolizer result is not a sign of poor health or a liver problem. It is an inherited trait that pharmacogenetic tests can report.
Where you may see it
- Clopidogrel, codeine and some antidepressant labels
- Pharmacogenetic test reports
- Pharmacist medication reviews
📄 How it looks on a report
In CYP2D6 poor metabolizers, plasma concentrations may be increased. Consider a lower starting dose.
🙅 What it does not mean
- It does not mean your liver is damaged.
- It applies to one enzyme, not to every medicine you take.
- A poor metabolizer status can mean more effect from some medicines and less from others.
🎯 Check yourself
Which of these is the right meaning of “Poor Metabolizer”?
🗒️ Questions to ask your doctor
🧾 Reports where you will see “Poor Metabolizer”
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💊 Medicines whose labels mention “Poor Metabolizer”
Plain-English explanations of each medicine, from its official FDA label.
- Clopidogrel
A platelet inhibitor of the P2Y12 type (a thienopyridine). It is a blood thinner that keeps platelets from sticking together.
🔗 Read more from trusted sources
- “Poor Metabolizer” on MedlinePlus ↗
US National Library of Medicine
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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.