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Serum or plasma concentration of substance measured by immunoassay (e.g., protein or antibody)

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

This test measures the amount of a specific protein or antibody in your blood, often used to detect or monitor certain conditions.

Quick summary

["Helps diagnose or track conditions like infections, autoimmune diseases, or protein-related disorders."]

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

Key facts at a glance

LOINC
81823-7
Short code
SACS Mut Anl Bld/T
Synonyms
SACS Mut Anl Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What This Test Measures

This test identifies the presence and quantity of a particular protein or antibody in your blood. The method used is an immunoassay, which detects specific substances by binding to them. The specimen collected is either serum (blood after clotting) or plasma (blood after centrifugation).

Why It’s Ordered

Doctors may order this test to diagnose or monitor conditions such as infections (e.g., viruses or bacteria), autoimmune diseases (e.g., rheumatoid arthritis), or to check for abnormal protein levels in the blood.

Common Uses

Common reasons include identifying immune responses, detecting hidden infections, or evaluating conditions affecting protein production or function.

Sample Collection

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum or plasma for testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Protein/antibody level (serum/plasma)

Frequently asked questions

How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on lab processing times and any follow-up testing required.
What are the normal ranges?
Normal ranges vary by protein/antibody tested and may be provided by your healthcare provider. They are not applicable to all tests in this category.
Can I eat or drink before this test?
For most blood tests, you can eat normally, but some tests (like glucose) may require fasting. Follow your doctor’s instructions for your specific test.
  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