Hydroxyzine concentration in plasma
This test measures the amount of hydroxyzine, a medication used to treat anxiety, allergies, or itching, in your blood plasma. It helps assess drug levels for therapeutic monitoring.
["This test checks if your hydroxyzine dose is within safe and effective ranges."]
Key facts at a glance
- LOINC
- 73338-6
- Short code
- hydrOXYzine ind plt IgM SerPl Ql FC
- Synonyms
- hydrOXYzine ind plt IgM 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 hydroxyzine long-term, have unusual side effects, or if you’re experiencing symptoms that might be related to drug levels. It can also be used to confirm compliance with your medication regimen.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm to draw blood. The process usually takes a few minutes, and you’ll feel minor discomfort for a short time.
What the Test Results Mean
Results are compared to general reference ranges for hydroxyzine in plasma. Low levels may indicate insufficient medication, while very high levels could signal overdose or improper metabolism.
Common Side Effects to Watch For
Hydroxyzine can cause drowsiness, dry mouth, or dizziness. If you experience severe symptoms like confusion, slow breathing, or extreme fatigue, contact your doctor immediately.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Hydroxyzine levels help prevent toxicity or inadequate treatment. For example, high levels may require dose adjustments, while low levels could prompt a prescription review. This test is particularly useful in patients with liver or kidney issues, as these organs play a key role in metabolizing the drug.
Short name
Hydroxyzine Level
Frequently asked questions
Why might my doctor request this test?
What does a low or high hydroxyzine level mean?
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 16, 2026. · Read our editorial policy