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 .
Light chains can be bound or free:
- When light chains link up with heavy chains, they are known as bound light chains.
- Normally, your plasma cells will make a small amount of extra light chains that don't bind with heavy chains. Instead, they are put into your bloodstream. These unlinked chains are known as free light chains.
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.
Other names: free kappa/lambda ratio, kappa/lambda quantitative free light, freelite, kappa and lambda free light chains, immunoglobulin free light chains, free light chain assay test