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Ethambutol Concentration in Serum (Quantitative)

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

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

Quick summary

["Your blood ethambutol levels help doctors monitor your dose and ensure safe, effective treatment."]

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

Key facts at a glance

LOINC
56025-0
Short code
Ethambutol Islt Slgr Mcbct AB 8.0
Synonyms
Ethambutol Islt Slgr Mcbct AB 8.0
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 Matters

Ethambutol is an important medication for tuberculosis (TB) treatment, but high levels can cause vision problems. This test helps prevent toxicity by checking how much ethambutol is in your blood.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood. This is usually quick and painless, though you may feel a slight pinch.

What the Results Mean

Results help doctors adjust your dose if needed. They don’t provide a direct “safe” range, but they guide whether your levels are too high or too low for effective treatment.

Common Reasons for This Test

Doctors order this test to check if ethambutol is working, to avoid side effects like vision changes, or to adjust your dose during treatment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Monitoring for Safety and Effectiveness

Short name

Ethambutol Level

Frequently asked questions

How often should I get this test?
Your doctor will determine timing based on your treatment plan. Typically, it’s done during active therapy to ensure proper dosing and side effect monitoring.
What if my levels are too high?
High levels may cause vision issues or other side effects. Your doctor will adjust your dose or switch medications if needed to keep levels safe.
Does this test affect my TB treatment?
No, this test is just a monitoring tool. It helps ensure your TB treatment stays effective while avoiding harm from the drug.
  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