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Hydralazine-induced Plasma Titer (Antibody) Measurement

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

This test checks for antibodies in your blood that may develop after taking the medication hydralazine, often used to treat high blood pressure.

Quick summary

["Assesses immune response to hydralazine, potentially linked to drug-induced lupus or other autoimmune reactions."]

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

Key facts at a glance

LOINC
73355-0
Short code
hydrALAZINE ind plt IgG SerPl Ql FC
Synonyms
hydrALAZINE 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’ve been taking hydralazine for a long time or if you experience symptoms like joint pain, fatigue, or rash that could suggest an immune reaction to the medication. It helps monitor whether your body is producing antibodies against hydralazine.

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 test measures the presence of antibodies in your plasma, which is the liquid part of blood without blood cells.

What the Results Mean

Results are qualitative (positive or negative) and indicate whether antibodies were detected. A positive result suggests your body may be reacting to hydralazine, which could require adjustments in medication or monitoring.

Possible Side Effects or Risks

Blood tests are generally safe, but rare risks include bruising, slight pain at the needle site, or a mild allergic reaction to the process. Antibody development is not harmful but may signal a need for further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Hydralazine-induced antibody formation can be associated with drug-induced lupus or other autoimmune conditions. While not always clinically significant, it may prompt closer monitoring of symptoms, medication adjustments, or additional testing to rule out systemic reactions.

Short name

Hydralazine Antibody Test (Plasma)

Frequently asked questions

What does a positive result mean?
A positive result means your body detected antibodies against hydralazine, which may indicate an immune response. This doesn’t always mean you have a serious condition, but it may signal that your provider should assess your symptoms or adjust your treatment.
Can I stop taking hydralazine if my test is positive?
Not necessarily. A positive test alone doesn’t mean you must stop hydralazine. Your healthcare provider will evaluate your symptoms, overall health, and other factors before deciding whether to change your medication or monitor you more closely.
How often will I need this test?
The frequency depends on your medical history, symptoms, and provider’s recommendations. Some patients may need this test annually or more often if they’ve had prior positive results or related symptoms.
  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