Bence-Jones Proteinuria (B.J. proteinuria) and Multiple Myeloma
July 11, 2022Chemical pathologyLab Tests
- This test is done on the urine of the patient.
- First-morning sample around 50 mL, uncontaminated urine in the container.
- For to know the amount of Bence-jones protein, 24 hours urine samples may be collected.
- A morning sample may be advised.
- If there is a delay, then refrigerate the sample.
Precautions for Bence-Jones Proteinuria
- Avoid dilute urine.
- If there is a delay in the test, then refrigerate the sample.
- Avoid heat because heat-coagulable protein can decompose, which will cause a positive result.
Indications for Bence-Jones Proteinuria
- This will help in the diagnosis of Multiple Myeloma.
- It may be used to monitor the treatment of multiple myelomas.
- This may be seen in Waldenstrom’s Macroglobulinemia.
History of Bence-Jones Proteinuria
- Bence-Jone proteins by heat test were described by Bence-Jones and were used to detect the light chain in the urine. Since then called Bence-Jones proteins.
- Monoclonal immunoglobulin, which is also called paraprotein or myeloma components, maybe:
- Or a fragment of immunoglobulin molecule.
- If these are fragments, these are usually light chains called Bence-Jones protein in the urine.
Definition of Bence Jones protein:
- This is an abnormal plasma or urine protein, consisting of monoclonal immunoglobulins light chains, excreted in neoplastic diseases and characterized by its unusual solubility properties as it precipitates at 50 °C to 60 °C and it redissolves at 90 °C to 100 °C. When cooled, then again reappears.
- There is the excretion of an abnormal light chain of immunoglobulins (kappa κ or lambda λ) in the urine of Multiple Myeloma patients, which is called Bence-Jones protein.
- In about 10% of the myeloma cases, B.J. protein is positive.
- B.J. protein is a single peptide chain with a molecular weight of 20,000.
- Serum exists in two forms κ and λ.
- These are abnormal light chain Immunoglobulin secreted from the clonal proliferation of B lymphocytes.
- B.J. proteins are presented in two forms:
- Monoclonal gammopathy.
- In free light chain disease.
- B.J. proteins are presented in two forms:
Pathophysiology of BJ proteins:
- These may be seen in tumor metastasis to bone, chronic lymphocytic leukemia, lymphoma, macroglobulinemia, and amyloidosis.
- B.J. proteins are very small in size, so easily filtered from the kidney glomeruli and can be detected in urine, and are difficult to find in the blood. So urine sample is used. Normally BJ proteins are not found in the urine.
- B.J. protein present in serum or urine or both depends upon the kidney function like:
- Bence Jones protein excreted in the urine:
- Around 70% (54% to 84%) of the multiple myeloma cases.
- 30% (0% to 78%) in Waldenstrom’s macroglobulinemia.
- Monoclonal gammopathy associated with lymphoproliferative malignancy show positive result in 20% (15% to 62%).
- In the case of benign secondary/idiopathic monoclonal gammopathy shows 10% (0% to 24%).
- This is the malignancy of plasma cells. These plasma cells involve the bone marrow and frequently produce multisystem diseases.
Signs and symptoms:
- Mostly the patients are over 50 years of age. The peak age is 60 to 65 years.
- About two-thirds of the cases are male., which may be seen in 70% of the cases.
- The most important symptom is bone pain.
- These patients may have signs and symptoms of:
- Weight loss, weakness, and GI symptoms are found in 35% to 65% of the cases.
- Neurological signs are seen in 30% to 50% of the cases.
- Liver enlargement is seen in 20% of the cases, while splenomegaly in 10%.
- Bone pain.
- Hypercalcemia. It is seen in 30% of the cases.
- Infections are seen in 10% to 50% of the cases. The common bacteria are encapsulated, like pneumococci. Other H.influenzae may also be seen.
- Pathological fractures are common.
- Markedly raised ESR.
- There is anemia.
- Frequent infections.
- Renal failure. Acute or chronic renal failure is seen in >50% of the cases.
Criteria for the diagnosis of multiple myeloma:
|Clinical criteria for the diagnosis||Signs/symptoms|
Diagnosis of multiple myeloma:
- Anemia is seen in 60% to 80% of the cases. This is normocytic-normochromic anemia.
- There is increased rouleaux formation of the RBCs due to the presence of abnormal proteins. This picture can be seen in 60% to 85% of the cases and gives clues to the possibility of multiple myeloma.
- TLC shows leucopenia in 15% to 20% of the cases.
- In 1% to 2% of cases, plasma cells (>5%) may be seen in the peripheral blood smear.
- Some people say it is plasma cell leukemia, but some say this number should be >20% plasma cells.
- Thrombocytopenia has been in around 10% of the cases.
- ESR is markedly raised in 90% of cases.
- Proteinuria is seen in 60% to 90% of the cases.
- Hypercalcemia is seen in about 30%.
- Serum albumin is decreased in about 50% of the patients.
- Hyperglobulinemia is seen in 60% (50% to 80%) of the patients.
- LDH level is raised in 20% to 40% of the cases.
- Radiological evidence has been in 80% to 85% of the patients.
- The most typical lesion is a punched-out, osteolytic lesion.
- The common site is a skull, vertebra, spines, and pelvis.
- There are increased chances for a pathological fracture.
- Bone marrow aspirate shows >20% of the plasma cells.
- Sometimes may see 5% to 30% of the plasma cells and the presence of a pathological fracture.
- If the plasma cells are <20%, then most plasma cells will show signs of immaturity.
- Bone marrow aspiration is diagnostic by the time S/S appears.
- Abnormal proteins show monoclonal immunoglobulins, about 75% to 80%of the myeloma patients, with 160,000 daltons or 7S.
- These are usually present in the gamma-globulin area, occasionally in the beta-globulin, and rarely in alpha-2-globulin.
- Myeloma patients show monoclonal gammopathy where IgG is 70%, IgA is 25%, and <2% are IgD or IgE.
- Some of the patients secret incomplete and low-weight proteins called Bence-Jones protein.
- Bence-Jones protein consists of light chains (κ or λ) and has a molecular weight of 40,000 daltons or 3.5 S.
- Multiple myeloma shows:
- IgG = 60% (50% to 71%).
- IgA = 25% (22% to28%).
- Bence-jones light chain = 20% (10% to 26%).
Urine tests for light chains:
- To perform the heat test:
- The urine must first be acidified by adding I ml of 2 molar acetate buffer to 4 ml of filtered urine.
- Urine is concentrated 5 to 100 times to find the small amount of Bence Jones protein.
- These proteins (light chains immunoglobulins) are soluble at room temperature.
- Precipitate at 60°C.
- Again disappear (redissolve) at boiling temperature or 80°C.
- These will reappear if the urine is cooled.
- Protein precipitation test: The sulphosalicylic acid positive test quantifies protein excreted in 24 hours of urine.
- Urine immunoelectrophoresis is the definitive test that allows differentiation between Kappa and Lambda chains in the urine.
- This test may be negative with the urine routine test strips.
NORMAL BJ protein
- Serum = Normally negative, B.J. protein is also negative in the urine.
- Qualitative urine = 0 in 50 x concentrated specimen.
- Quantitative urine :
- Kappa (κ) = <2.5 mg/dL.
- Lambda (λ) = <5.0 mg/dL.
B.J Protein may be found in:
- These are present in 75% of Multiple Myeloma patients.
- Chronic lymphocytic leukemia.
- In Lymphoma.
- Waldenstrom macroglobulinemia.
- Monoclonal gammopathy of unknown significance.
- Tumor metastasis to the bone.
Bence-Jones proteinuria is seen in:
It indicates the various types of gammopathies. 80% of tests are positive in:
- Multiple myeloma (70% positivity).
- Waldenstrom macroglobulinemia.
- Primary amyloidosis.
- Benign monoclonal gammopathy.
- Adult Fanconi syndrome.
Roughly 20% show false-positive results in:
- Connective tissue diseases like rheumatoid arthritis, SLE, scleroderma, Wegner granulomatosis, and polymyositis.
- Chronic renal insufficiency.
- Lymphoma and leukemia.
- Metastatic carcinoma of the GI tract and the lungs.
- Presence of radiographic contrast material.
- High doses of penicillin and aminosalicylic acid.
- Dilute urine may give a false-negative result.
- In case of positive BJ proteinuria by heat, it should always be confirmed by the electrophoresis and immunoelectrophoresis/immunofiltration of concentrated urine.
- A heat test is not reliable, and should not be used to confirm the diagnosis.
- The reagent strips for the urine protein do not detect BJ protein.