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Serum or Plasma Substance Concentration by Immunoassay (e.g., Anti-Drug Antibody)

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

This test measures the presence of antibodies that may indicate exposure to certain medications, toxins, or biological substances in your blood.

Quick summary

["Helps detect immune responses to drugs or foreign substances in your system."]

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

Key facts at a glance

LOINC
109036-4
Short code
S pneum Da 9V IgG Msmt Ser
Synonyms
S pneum Da 9V IgG Msmt Ser
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 recently started a new medication, received a biological treatment (like an antibody therapy), or if you have a condition that could affect how your body processes substances. It can also be used in monitoring for drug interactions or immune responses to toxins.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Wear comfortable clothing and plan to stay near the testing site for a short time.

How the Test Is Performed

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure is quick. The blood sample is then sent to a lab for testing using an immunoassay method to detect specific antibodies.

What the Results Mean

Results are qualitative (positive or negative) and indicate whether antibodies were found. A positive result suggests your immune system may have recognized and responded to the substance, while a negative result means no detectable antibodies were found.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Drug Antibody Screen (Serum/Plasma)

Frequently asked questions

What does a positive result mean?
A positive result means your immune system detected antibodies against the substance tested, which could indicate exposure, a reaction to treatment, or an underlying immune response. This may influence further medical decisions, such as adjusting medication or monitoring closely.
Can I eat or drink before this test?
If your blood is drawn in the morning, fasting for 8–12 hours is often recommended. Otherwise, you can eat and drink normally unless instructed otherwise by your provider.
How long will I need to wait for results?
Results are typically available within 1–3 business days, depending on lab processing times. Your healthcare provider will discuss them with you during your follow-up visit.
  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