Skip to content

Serum or plasma concentration of immunoglobulin G (IgG) by nephelometry

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections and is important for long-term immunity.

Quick summary

["IgG levels help assess immune function and identify potential deficiencies or excesses."]

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

Key facts at a glance

LOINC
96255-5
Short code
SLEV IgG+IgM Pnl Ser
Synonyms
SLEV IgG+IgM Pnl Ser
Category
chemistry
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 Might Be Ordered

Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or if you’re being evaluated for conditions like HIV, autoimmune diseases, or certain genetic disorders. It may also be checked during pregnancy to monitor fetal development or in people with chronic illnesses like cancer or kidney disease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours if the test involves drawing blood. Wear a comfortable shirt with an easy armhole for the blood draw. If you’re taking medications that affect blood clotting, let your provider know.

What Happens During the Test

A healthcare professional will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch or discomfort, but it usually lasts only a few seconds. The blood sample is then sent to a lab for analysis using a nephelometry method, which measures how much light is scattered by the IgG particles in your serum or plasma.

What the Results Mean

Results are compared to a general reference range, which can vary by lab. Low IgG levels may suggest immune deficiencies, while very high levels could indicate conditions like multiple myeloma or chronic infections. Your provider will discuss the results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What causes IgG levels to be low?
Low IgG levels can result from primary immune deficiencies, such as selective IgA deficiency or common variable immunodeficiency, or secondary causes like malnutrition, chronic liver disease, or certain medications. It may also occur in people with HIV/AIDS or those undergoing chemotherapy.
What are the symptoms of abnormal IgG levels?
Symptoms of low IgG may include frequent or severe infections (especially respiratory or sinus infections), slow wound healing, frequent ear infections, or recurrent pneumonia. Symptoms of high IgG may include chronic fatigue, joint pain, or signs of autoimmune activity like rash or swelling.
How often should IgG levels be checked?
The frequency of IgG testing depends on your health condition. People with known immune deficiencies or chronic illnesses may need regular monitoring. Pregnant individuals or those with specific risk factors may also have periodic checks. Always follow your healthcare provider’s recommendations.
  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