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Serum or Plasma Substance Concentration by Immunoassay (General Protein or Antibody Screening)

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

This test measures certain proteins or antibodies in your blood, often used to check for infections, immune responses, or other conditions affecting protein levels.

Quick summary

["Helps identify potential health issues by detecting abnormal protein or antibody presence."]

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

Key facts at a glance

LOINC
98363-5
Short code
XR SIJ-L AP+Obl
Synonyms
XR SIJ-L AP+Obl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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

What This Test Measures

This test uses an immunoassay method to detect specific proteins or antibodies in your serum or plasma. It may screen for a wide range of substances, including but not limited to immunoglobulins (antibodies), acute-phase reactants, or other proteins that could indicate inflammation, infection, or autoimmune conditions.

Common Uses

Such tests are commonly used in initial screening for conditions like infections (e.g., viral or bacterial), autoimmune diseases, or monitoring protein levels in chronic diseases.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate serum (liquid part after clotting) or plasma (liquid part without clotting), depending on the test requirements.

Test Process

The sample is analyzed using an immunoassay technique, which detects and quantifies specific proteins or antibodies. Results are compared to reference ranges to determine if levels are within normal limits or elevated/decreased.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated or abnormal protein/antibody levels can signal infections, immune disorders, liver disease, kidney problems, or other systemic conditions. Low levels may indicate malnutrition, protein loss, or certain genetic disorders. Always discuss results with your healthcare provider for accurate interpretation.

Short name

Protein/antibody screening test

Frequently asked questions

Why might I need this test?
Your doctor may recommend this test if you have symptoms like fever, unexplained weight loss, fatigue, or if they suspect an infection, autoimmune disease, or another condition affecting protein levels in your blood.
What does a normal result mean?
A normal result means the protein or antibody levels detected are within the expected range for healthy individuals. However, this does not rule out all possible conditions—your doctor will consider your overall health and symptoms when interpreting results.
Can lifestyle changes affect this test?
Yes, certain lifestyle factors like diet (e.g., protein intake), hydration, or medications can influence protein levels. Your doctor may advise you to avoid certain foods or medications before the test if instructed.
  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