Free Light Chains (Kappa & Lambda) test

Your doctor may order a free light chains test when he/she suspects a disorder related to plasma cells such as cancer, in particular, multiple myeloma. Multiple myeloma presents with multiple tumours, specifically in the bones. Tumour cells damage the bones and lead to an increase in calcium in the blood. They prevent the bone marrow from producing healthy red blood cells, resulting in anaemia. The tumours also lead to high levels of abnormal proteins in the blood that can damage the kidneys. 

Multiple myeloma may present with the following symptoms:

• Pain in the bones, especially in the back and ribs
• A tendency to get fractures
• Easy bleeding after a minor injury
• Weakness in arms and legs
• Tiredness
• Frequent infections or fever with no known cause
• Nausea
• Vomiting
• Constipation
• Increased frequency of urination
• Increased thirst
• Restlessness
• Confusion
• Kidney dysfunction
• Inflammation

In some cases, multiple myeloma leads to another condition called amyloidosis, which affects the nerves, skin, kidneys and heart. The free light chains test is also used to diagnose amyloidosis, which presents with symptoms such as:

• Tingling or numbness in the feet and legs
• Swelling in body
• Purple-coloured spots on the skin
• Swollen tongue
• Diarrhoea

This test may also be used to monitor conditions such as multiple myeloma and their response to treatment.

You don’t have to do any special preparation for this test. If you are taking any medicines or supplements, now is the time to inform your doctor.

A laboratory technician will draw a small amount of blood from a vein in your arm. He/she will collect the sample in a pink-top tube. The tube contains an anticoagulant called EDTA, which prevents the blood from clotting.

The procedure is simple with minimal risks. After the test, some individuals may feel dizzy or experience bleeding, infection or haematoma at the site of needle insertion in the arm. Please consult your doctor if you notice persistent bruising or pain at the site.

The free light chains test measures the amount of lambda and kappa light chains separately and calculates the ratio between kappa and lambda chains in blood. 

Normal results:

• Lambda quantitative free light chains: 5.7-26.3 mg/L (milligrams per litre)
• Kappa quantitative free light chains: 3.3-19.4 mg/L
• Kappa/lambda free light chain ratio: 0.26-1.65

People with multiple myeloma and normal levels of free lambda and kappa chains have a five-year survival rate of 80%. This means that out of the individuals who are diagnosed with multiple myeloma and have normal levels of free lambda and kappa chains, 80% survive for five years.

Abnormal results: 

High levels of free light chains indicate an abnormality related to plasma cells.

• High levels of kappa light chains and a raised kappa/lambda ratio are seen in plasma cell disorders that produce more kappa chains. On the other hand, high levels of lambda light chains and a low kappa/lambda ratio are seen in plasma cell disorders that cause excess lambda chains. In people diagnosed with these disorders, decreased levels of free light chains and a kappa/lambda ratio closer to normal indicate a good response to treatment.
• In individuals with multiple myeloma, high levels of lambda and kappa free light chains indicate a low survival rate. An abnormal kappa/lambda ratio indicates a shorter survival period in such individuals.
• In individuals with amyloidosis, high levels of lambda and kappa free light chains are indicative of an increased risk of death while decreased levels of lambda and kappa free light chains suggest an improvement and a longer period of survival. A kappa/lambda ratio below or beyond the normal range is indicative of amyloidosis.
• The ratio < 0.26 suggests plasma cell disorder is associated with large quantity of kappa chains. Whereas a ratio >1.65 indicates plasma cell disorder that produces high amount of lambda chains. 

Thus, levels of free kappa and lambda chains along with the kappa/lambda ratio are useful in understanding the prognosis of disease and the effect of medicines on the progress of the disease. The results of the test are sometimes correlated with the results of a protein electrophoresis test.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.