Ethambutol concentration in serum/plasma (quantitative drug level)
This test measures the amount of the medication ethambutol in your blood. Ethambutol is used to treat tuberculosis and may be prescribed as part of a multi-drug regimen.
["Your ethambutol level helps doctors check if the drug is working properly and adjust your dose if needed."]
Key facts at a glance
- LOINC
- 25230-4
- Short code
- Ethambutol Islt Slgr Mcbct AB 2.5
- Synonyms
- Ethambutol Islt Slgr Mcbct AB 2.5
- 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
Your healthcare provider may order this test if you’re taking ethambutol to treat tuberculosis. It helps ensure the drug is at an effective level in your blood without causing too much of an effect, which could be harmful. This is especially important if you’re taking other medications or have certain health conditions.
How the Test Works
A small blood sample is taken from a vein in your arm. The sample is then analyzed to measure the concentration of ethambutol in your serum or plasma using a sensitive laboratory method.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to stop taking certain medications or supplements for a short time before the test if instructed by your doctor. Avoid eating or drinking anything for at least 8 hours before the test if directed.
What to Expect During the Test
The blood draw is quick and typically painless. You may feel a slight pinch or discomfort, but most people tolerate it well. You can usually return to your normal activities immediately afterward.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Ethambutol levels help monitor your treatment for tuberculosis. Too little drug may mean the infection isn’t fully controlled, while too much could increase the risk of side effects like vision changes or nerve damage. Regular testing ensures your dose is optimized for safety and effectiveness.
Short name
Ethambutol Level
Frequently asked questions
When might I need this test?
What do my results mean?
Can I eat or drink before this test?
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