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Serum Cycloserine Concentration (Quantitative)

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

This test measures the amount of cycloserine, a medication used to treat certain bacterial infections, in your blood. It helps your healthcare provider monitor your dose and ensure it’s working safely.

Quick summary

["Check your cycloserine levels to avoid overdose or side effects while treating your infection."]

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

Key facts at a glance

LOINC
25208-0
Short code
cycloSERINE Islt Slgr Mcbct AB 20.0
Synonyms
cycloSERINE Islt Slgr Mcbct AB 20.0
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-m
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 Is This Test Done?

Your doctor may order this test if you’re taking cycloserine to treat tuberculosis (TB) or other serious infections. It helps assess whether your medication levels are within the safe range and if the drug is effectively fighting the infection.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. The process is quick and typically painless. If you’re on blood thinners, let your doctor know before the test.

What the Test Results Mean

Results help determine if your cycloserine dose is appropriate. Too little may mean the infection isn’t fully treated, while too much can cause harmful side effects. Your doctor will discuss the results with you.

Common Side Effects to Watch For

Cycloserine can cause side effects like nausea, dizziness, or trouble sleeping. If you experience severe symptoms (e.g., seizures, confusion, or rash), seek medical attention immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Cycloserine is a second-line antibiotic used for hard-to-treat infections like TB. Monitoring levels ensures safe dosing and prevents resistance or toxicity. Low levels may indicate poor absorption, while high levels may require dose adjustments or alternative treatments.

Short name

Cycloserine Level

Frequently asked questions

Why was I asked to take this test?
Your doctor may have ordered this test to confirm your cycloserine dose is correct or to check if the medication is working as intended in your body.
What does a low or high cycloserine level mean?
A low level might mean your body isn’t absorbing enough medication, while a high level could signal overdose or poor kidney function. Your doctor will interpret results based on your medical history and symptoms.
Can I eat or drink before this test?
You can eat and drink normally unless instructed otherwise. Avoid caffeine or alcohol before the blood draw, as they may affect test results.
  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