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Immunoglobulin Heavy Chain Free Light Chain Ratio (Serum)

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

This test measures the ratio of free light chains from heavy and light chains of antibodies in your blood. It helps assess conditions affecting antibody production or breakdown, such as multiple myeloma or other plasma cell disorders.

Quick summary

["This ratio helps doctors diagnose and monitor blood disorders linked to abnormal antibody production."]

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

Key facts at a glance

LOINC
107200-8
Short code
IgH FR1 Spec
Synonyms
IgH FR1 Spec
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
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 have symptoms like unexplained fatigue, frequent infections, bone pain, or kidney issues. It’s also used to monitor conditions like multiple myeloma, lymphoma, or other plasma cell disorders where abnormal antibody production is suspected.

What to Expect Before the Test

No special preparation is needed. You’ll have a blood sample drawn from a vein, usually in your arm. The process is quick and typically painless.

How the Test Works

Blood is collected and analyzed to measure free light chains from antibodies. The test compares the amounts of free light chains from heavy and light chains to determine the ratio.

Possible Results and Interpretation

Results are compared to reference ranges for healthy individuals. Elevated ratios may indicate conditions like multiple myeloma, where too many abnormal light chains are produced. Your doctor will discuss findings in the context of your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Light Chain Ratio

Frequently asked questions

What causes abnormal light chain ratios?
Abnormal light chain ratios are often linked to conditions like multiple myeloma, where plasma cells produce too many abnormal light chains. Other causes may include certain lymphomas, amyloidosis, or chronic kidney disease. Your doctor will consider your full medical picture.
How often should this test be repeated?
If you have a condition like multiple myeloma, your doctor may order this test regularly to monitor disease activity. Frequency depends on your treatment plan and symptoms. Follow-up schedules are tailored to your needs.
Can diet or medications affect this test?
Dietary changes or certain medications (like some chemotherapy drugs) may indirectly influence antibody production or kidney function, potentially affecting light chain levels. Always inform your doctor about all medications or supplements you take before testing.
  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