Ethambutol concentration in serum/plasma (quantitative measurement)
This test measures the amount of ethambutol, a medication used to treat tuberculosis, in your blood.
["Your blood ethambutol level helps doctors check if your dose is working properly."]
Key facts at a glance
- LOINC
- 55674-6
- Short code
- Ethambutol Islt Slgr Mcbct AB 2.0
- Synonyms
- Ethambutol Islt Slgr Mcbct AB 2.0
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- method-for-slow-growing-mycobacteria-antibiotic-concentration-at-ug-ml
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Doctors may order this test if you’re taking ethambutol to treat tuberculosis (TB). It helps ensure the medication is at an effective level in your blood without causing harmful side effects. This is especially important for long-term treatment to prevent resistance or toxicity.
What to Expect Before the Test
No special preparation is needed. A healthcare provider will draw blood from a vein, usually in your arm. You may feel a slight pinch, but the procedure is quick and usually painless. If you’re on other medications, let your provider know.
What the Results Mean
Results are used to adjust your dose if needed. Low levels may mean the medication isn’t working well, while very high levels could indicate side effects. Your doctor will interpret these results in the context of your treatment plan.
Possible Side Effects
Ethambutol can cause side effects like vision changes (blurred or reduced color vision), which is why monitoring blood levels is important. Other rare but serious side effects include kidney problems or allergic reactions. Report any unusual symptoms to your doctor.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Ethambutol Level
Frequently asked questions
What questions do patients often ask about this test?
Can I eat or drink before this test? You can eat and drink normally unless your doctor specifies otherwise. No fasting is required for this test.
Will my results affect my medication? Yes, your doctor may change your dose if levels are too low or too high to ensure effectiveness and safety.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy