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Clarithromycin Concentration in Serum (Quantitative)

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

This test measures the amount of clarithromycin, a medication used to treat bacterial infections, in your blood.

Quick summary

["Clarithromycin levels help ensure your dose is effective and safe."]

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

Key facts at a glance

LOINC
43991-9
Short code
Clarithro Islt Slgr Mcbct AB 6.0
Synonyms
Clarithro Islt Slgr Mcbct AB 6.0
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 clarithromycin to confirm your blood levels are within the recommended range. This helps prevent side effects or insufficient treatment of infections like pneumonia, ear infections, or skin infections caused by certain bacteria.

How the Test Works

A blood sample is taken from a vein in your arm. The sample is then analyzed using an immunoassay method to measure the precise concentration of clarithromycin in your serum.

What to Expect Before the Test

No special preparation is usually needed, but inform your provider if you’re taking other medications or have allergies. Avoid eating or drinking for 1 hour before the test if instructed.

What the Results Mean

Results are typically reported in micrograms per milliliter (µg/mL). Your provider will interpret the results in relation to your specific dose and medical condition. Abnormally high or low levels may indicate issues with how your body absorbs or processes the medication.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clarithromycin levels are critical for managing infections caused by bacteria resistant to other antibiotics. Optimal levels ensure effective treatment while minimizing risks of side effects like nausea, diarrhea, or rash. Monitoring helps adjust doses for patients with liver or kidney issues, ensuring safety and efficacy.

Short name

Clarithromycin Level

Frequently asked questions

What causes clarithromycin levels to be too high?
High levels may result from improper dosing, liver problems that slow drug metabolism, or taking other medications that interfere with clarithromycin’s absorption or breakdown.
How long does it take to get results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time.
Can I eat or drink before this test?
Typically, you should fast for 1 hour before the test if instructed by your provider, but always follow their specific instructions.
  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