Skip to content

Rifampin Drug Concentration in Plasma (Quantitative)

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

This test measures the amount of the antibiotic rifampin in your blood plasma. It helps doctors check how well your body is responding to the medication and whether it’s at a safe level.

Quick summary

["Rifampin levels help ensure your treatment is effective and avoid potential side effects."]

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

Key facts at a glance

LOINC
73166-1
Short code
rifAMPin ind plt IgG SerPl Ql FC
Synonyms
rifAMPin ind plt IgG SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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 rifampin for a bacterial infection, such as tuberculosis or certain skin infections. It’s often done during treatment to monitor drug levels, especially if you’re taking other medications that could interact with rifampin.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast before the test, but this depends on your doctor’s instructions. A blood sample will be taken from a vein in your arm, similar to other routine blood tests.

What the Test Results Mean

Results are used to guide your treatment plan. Low levels might mean your dose needs adjustment, while very high levels could signal potential toxicity. Your doctor will interpret the results in the context of your overall health and medication regimen.

Common Reasons for Testing

Doctors may test rifampin levels to ensure proper dosing, especially if you’re taking other medications that rifampin can affect (like birth control pills, HIV medications, or warfarin). It’s also important for monitoring in patients with kidney or liver issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Rifampin Level

Frequently asked questions

How long does it take to get the results of this test?
Results are typically available within 1 to 3 business days, depending on your lab and healthcare provider. Your doctor will contact you once they have the results to discuss them further.
Can I eat or drink anything before this test?
Check with your doctor or lab technician about fasting requirements. Some labs may ask for fasting, while others may not. Follow their specific instructions to ensure accurate results.
Will I feel any pain or discomfort during the blood draw?
You may feel a slight pinch or sting when the needle is inserted, but it usually goes away quickly. Most people experience minimal discomfort afterward. If you’re nervous, let your healthcare provider know—they may offer options like numbing cream.
  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