Bence Jones protein estimation: Introduction, principle, test procedure

Bence Jones (B-J) Protein Estimation: Introduction, Principle, Test Procedure and Confirmatory Test

Bence Jones protein estimation flowchart

Bence Jones (B-J) protein

Bence Jones protein is the light chain of immunoglobulins. It is observable in urine in the case of plasma cell cancer (multiple myeloma).

Introduction of Bence Jones Protein

Bence Jones protein consists of dimers of either kappa or lambda (K/λ) light chains from immunoglobulins (IgS). The molecular weight is very small about 44,000 Dalton, hence it is usually filtered through the normal glomerulus . It was first described by Henry Bence Jones in 1847.

Principle of Bence Jones Protein

Bence Jones protein has usually solubility properties. It precipitates when boiled to 40-60°C, but becomes soluble when boiled. It reappears after cooling . There is malignant proliferation of plasma cells in multiple myeloma ( a type of cancer) , usually in the bone marrow. This disease is associated with Bence Jones proteins. Nearly 50-80% patient with multiple myeloma will have Bence Jones proteins in their urine.

Requirements for Bence Jones Protein Estimation

Urine
24-hours ( a day) urine sample is useful for this test. For this sample, you must collect all of your urine for 24 hours. Empty your bladder completely first in the morning without collecting it. Note the time. Then collect your urine every time you go to the bathroom over the next 24 hours. Collect it in a container that you have provided from your laboratory.
Urine protein electrophoresis (UPEP): For this test, there is no need of a 24-hour sample. 30-50 ml of random sample is sufficient for testing. This test checks the levels of proteins in the urine, including Bence-Jones proteins.
Test tubes
Test tube holder
Sprit lamp
Acetic acid
Nirtic acid

Test procedure for Bence Jones Protein

Take 5 drops urine in a clean tube.
Heat up to 60°C and observe for cloudiness.
If cloudiness exists, it may be due to protein or carbonate or phosphate or nucleoprotein or mucin.
Add 2-3 drops acetic acid.
If cloudiness disappears, it may be due to either carbonate or phosphate.
When cloudiness does not disappear, add 2-3 drops nitric acid.
If cloudiness disappears, it may be due to nucleoprotein or mucin.
When cloudiness persists, protein present.
Now, boil up to 100°C.
If cloudiness disappears, cool to 60°C.
cloudiness reappears, which is Bence Jones protein.

Clinical Significance of the Bence Jones Protein

This test is useful when you have some of these symptoms like-

Bone pain or breaks, especially in the back, hips, or skull
High level of blood calcium
Low levels of red blood cells (anemia) or white blood cells (leucopenia) or platelets (thrombocytopenia)
Nervous system problems e.g. pain, numbness, or weakness
Stroke-like symptoms such as confusion and dizziness
Weakness and swelling of the legs
Variety of infections

Confirmatory test for Bence Jones Protein

Serum protein electrophoresis is the confirmatory test for Bence Jones protein.

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