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Serum Free Light Chains (Lambda)

Blood

Serum Free Light Chains (Lambda)

Also known as: Free Lambda, Lambda FLC

COMMON RANGE

6.7 – 34.6

mg/L

2.82

37.5

Mayo Clinic Laboratories

Adult

↗

See all sources ↓

Reference ranges across 10+ sources

Adult reference ranges from 2 entries across 2 named sources, shown in mg/L. Compare side-by-side.

SOURCE

SEX

AGE

RANGE

VISUAL

CITE

ARUP Laboratories

All

≥18y

5.71 – 26.3 mg/L

↗

Mayo Clinic Laboratories

All

≥18y

6.7 – 34.6 mg/L

↗

ARUP Laboratories

All · ≥18y

↗

5.71 – 26.3 mg/L

Mayo Clinic Laboratories

All · ≥18y

↗

6.7 – 34.6 mg/L

About Serum Free Light Chains (Lambda)

A free light chains test measures the level of free light chains in your blood. Light chains are proteins made by plasma cells, a type of white blood cell. Light chains usually link up with other proteins called heavy chains. Together, the light and heavy chains make immunoglobulins, also called antibodies. Antibodies are proteins that your immune system makes to fight germs such as viruses and bacteria.

There are two types of light chains: lambda and kappa light chains. You will usually have some of each in your blood. A free light chains test measures the amount of lambda and kappa free light chains in your blood.

If the amount of free light chains is higher or lower than normal, it may be a sign of a disorder of the plasma cells. These disorders include multiple myeloma, a cancer that begins in the plasma cells, and amyloidosis, a condition that occurs when abnormal proteins build up and collect in different organs and tissues.

Main source: MedlinePlus ↗

Useful for

Measure free lambda light chains in your blood, alongside kappa, and compare them as a kappa-to-lambda ratio.

Help find or follow plasma cell disorders that mainly produce lambda light chains, such as some types of multiple myeloma, AL amyloidosis, light-chain deposition disease, and non-secretory myeloma.

Help diagnose plasma cell disorders that don't show up on standard blood or urine protein tests.

Help follow how well treatment for these disorders is working over time, since changes in lambda free light chains can show whether the abnormal plasma cells are growing or shrinking.

Main source: MedlinePlus ↗

Interpretation

Your results will show the amounts of lambda and kappa free light chains in your blood. They will also provide a comparison between the two, called a ratio.

A high lambda free light chain level with a low kappa-to-lambda ratio suggests that one type of plasma cell is making too much lambda light chain, which can be a sign of a plasma cell disorder.

If both kappa and lambda are high but the ratio is normal, this often means the immune system is being broadly stimulated, such as in some chronic infections or autoimmune diseases.

Kidney problems can also raise free light chain levels because the kidneys normally clear them out. In this case, the kappa-to-lambda ratio is more useful than the lambda value alone.

To understand the results of a free light chains test, your provider will consider your symptoms, medical history, and the results of other blood tests, such as serum and urine protein electrophoresis.

For general wellness information only. Talk to a clinician about your specific results.

Main source: MedlinePlus ↗

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Related biomarkers

Often tested alongside serum free light chains (lambda) or part of the same panel.

White Blood Cells (WBC)

Blood

Red Blood Cells (RBC)

Blood

Hemoglobin (Hgb)

Blood

Hematocrit (Hct)

Blood

Platelets (PLT)

Blood

Mean Corpuscular Volume (MCV)

Blood

Sources

ARUP Laboratories

Mayo Clinic Laboratories

Last updated 2026-05-02

This page aggregates publicly available reference data and clinical information from Mayo Clinic Laboratories and other sources. For general wellness information only — not medical advice. For diagnosis or treatment of any condition, talk to a qualified clinician.

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