Theophylline Concentration (Serum or Plasma)
This test measures the amount of theophylline, a medication derived from tea leaves, in your blood. Theophylline is used to treat breathing problems like asthma or chronic obstructive pulmonary disease (COPD).
["Your doctor may order this test to check if your theophylline levels are within the safe range for your treatment."]
Key facts at a glance
- LOINC
- 46081-6
- Short code
- Theophylline Ur-sCnc
- Synonyms
- Theophylline Ur-sCnc
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 10
- Ref high
- 20
- Critical range
- — – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may recommend this test if you’re taking theophylline to manage breathing issues. They might also order it to monitor your response to the medication, check for side effects, or adjust your dose. This helps ensure the medication is effective and safe for you.
What to Expect Before the Test
No special preparation is needed for this test. You may have a small needle inserted into your arm or a blood sample drawn from a vein. If you’re taking theophylline, your provider may ask you to stop it temporarily before the test, depending on your situation.
What Happens During the Test?
A healthcare professional will collect a blood sample from a vein in your arm. The sample is then sent to a lab for analysis. The test measures the amount of theophylline in your blood, usually reported in micrograms per milliliter (mcg/mL).
What the Results Mean
Results will show your current theophylline level. High levels can cause side effects like nausea, rapid heartbeat, or trouble sleeping, while low levels may mean the medication isn’t working as intended. Your doctor will interpret the results in the context of your symptoms and treatment plan.
Reference range
Therapeutic: 10-20 mcg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Theophylline is a bronchodilator used to relieve symptoms of asthma and COPD. Monitoring levels helps prevent toxicity (too much) or insufficient effectiveness (too little). Abnormal results may prompt dose adjustments, medication changes, or further evaluation of your breathing condition.
Short name
Theophylline Level
Frequently asked questions
What causes theophylline levels to be checked?
How long does it take to get the results?
Can I eat or drink before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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 17, 2026. · Read our editorial policy