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Ethambutol Serum Concentration (Quantitative)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of the drug ethambutol in your serum. Ethambutol is used to treat tuberculosis and may be prescribed as part of a multi-drug regimen.

Quick summary

["Your doctor may check this level to ensure you’re taking the right dose and to avoid potential side effects."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
25194-2
Short code
Ethambutol Islt Slgr Mcbct AB 5.0
Synonyms
Ethambutol Islt Slgr Mcbct AB 5.0
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

Your healthcare provider may order this test if you’re taking ethambutol to treat tuberculosis. They may also check it during treatment to monitor your response and adjust your dose if needed. This helps prevent side effects like vision changes or nerve damage.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, typically drawn from a vein in your arm. The process is quick and usually painless.

What the Results Mean

Results are used to guide your treatment plan. Too much or too little ethambutol can affect how well your body responds to the medication. Your doctor will discuss these findings with you.

Common Side Effects to Watch For

While rare, ethambutol can cause side effects like vision changes (e.g., blurred or reduced color vision) or nerve-related issues. If you notice these symptoms, contact your doctor immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Ethambutol Level

Frequently asked questions

What causes this test to be ordered?
This test is ordered primarily to monitor ethambutol levels in patients taking the medication for tuberculosis. It helps ensure therapeutic drug levels are maintained while minimizing risks of toxicity.
How often should this test be done?
The frequency depends on your treatment plan. Your doctor may check it weekly or monthly during active treatment, then less often as you complete your course.
Can lifestyle or diet affect this test result?
Generally, diet or lifestyle changes don’t directly impact ethambutol levels in serum. However, always follow your doctor’s instructions regarding medications and supplements to avoid interactions.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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