Determining the concentration of this parameter is especially important in distinguishing tubular from glomerular nephropathy.
The level of serum beta 2 microglobulin also increases in all conditions of increased cell turnover, such as inflammation, autoimmune disorders and infectious diseases. In these contexts, the value is not diagnostic for specific pathologies, but it can direct the doctor to discriminate or investigate with other tests the causes that he suspects are at the base of the alteration or of the symptoms.
Beta 2 microglobulin is also used as a tumor marker, meaning that the increase in its plasma concentrations can be related to the presence of a neoplastic process.
Note. Beta 2 microglobulin is found predominantly in plasma, but is also present in small quantities in cerebrospinal fluid and urine.
of the immune system, as a constant subunit of class I histocompatibility antigens (note: more generally, the B2M protein is found - in variable quantities - on the surface of all nucleated cells). Beta 2 microglobulin is also found in blood and other biological fluids (urine and cerebrospinal fluid) as an expression of cell turnover (turnover).
B2M is filtered by the renal glomerulus and reabsorbed in the tubules. For this reason, its determination in the laboratory is important for establishing the state of health of the kidneys.
. Consequently, B2M values in blood and other biological fluids increase.The beta 2 microglobulin test can be used when it is necessary to distinguish between glomerular or tubular damage. The dosage of this parameter is also prescribed to monitor the course of previously diagnosed kidney diseases.
Sometimes, beta 2 microglobulin testing is indicated to monitor people exposed for occupational reasons to cadmium or other heavy metals.
To know
The activation of the immune system increases the release of beta 2 microglobulin by T and B lymphocytes. The concentrations of the protein also increase following pathologies that involve an overactive cell turnover. In such situations, however, the beta 2 microglobulin does not it is specific for no particular pathology.
When is the exam prescribed?
The doctor may instruct a blood and / or urine beta 2 microglobulin test to be performed when the patient has signs and symptoms of kidney dysfunction, such as:
- Swelling (edema), particularly around the eyes or face, wrists or ankles
- Foamy or bloody urine
- Protein in the urine;
- Fatigue;
- Nausea.
The beta 2 microglobulin test can be ordered when the doctor wants to distinguish between tubular and glomerular nephropathies:
- The increase of the parameter in the urine is of importance in the diagnosis of renal tubular pathologies.
- The dosage of beta 2 microglobulin in the blood is useful, however, as an index of glomerular filtration.
Evaluation of beta 2 microglobulin may also be recommended periodically to determine early renal dysfunction when a patient has been exposed, for occupational reasons, to high concentrations of cadmium and / or other heavy metals, such as mercury.
Related exams
The dosage of beta 2 microglobulin can be prescribed both in blood and in urine, in association with the evaluation of other parameters indicative of renal function, such as:
- Azotemia;
- Creatinine;
- Microalbuminuria.
In addition, the doctor may indicate the simultaneous execution of the following analyzes:
- Complete blood count;
- ESR (erythrocyte sedimentation rate);
- PCR (C-reactive protein);
- Ferritin;
- LDH (lactate dehydrogenase).
The combination of these tests is useful in establishing the presence of damage, determining the extent of organ dysfunction and distinguishing pathologies of the glomeruli from those of the renal tubules.
Other indications
- Dialysis-related amyloidosis: in long-term dialysis patients, high concentrations of beta 2 microglobulin can accumulate in various tissues and joint spaces; the examination of this parameter can therefore be used to monitor this condition, in association with the biopsy of the involved tissue.
- Kidney transplant: In some cases, a B2M urine test may be ordered to detect early signs of rejection.
- Renal insufficiency: the determination of the concentration of beta 2 microglobulin provides more information on the prognosis of the subject.
- Hematological tumors: the beta 2 microglobulin assay is used as a tumor marker for some neoplastic processes affecting blood cells (multiple myeloma and lymphoma). This parameter is not diagnostic for specific pathologies, but is associated with tumor extension and can provide the clinician with additional information on disease progression and treatment efficacy. It should also be noted that the beta 2 microglobulin assay intended as a tumor marker is not considered useful in general population screening.
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High concentrations of beta 2 microglobulin may indicate the presence of other conditions:
- Amyloidosis related to dialysis;
- Organ rejection in renal transplant patients;
- Cadmium poisoning.
An increase in blood and urine beta 2 microglobulin has been observed in certain hematological cancers, including:
- Multiple myeloma;
- Leukemia;
- Lymphoma.
The increase in beta 2 microglobulin can also be found in other diseases associated with an increase in the rate of cell production or destruction and in conditions characterized by the involvement of the immune system, as in the case of autoimmune diseases (eg lupus erythematosus, rheumatoid arthritis, etc. .) or chronic inflammatory diseases (e.g. Crohn's disease).
Therefore, an increase in beta 2 microglobulin concentrations can also be detected under the following conditions:
- Infectious diseases (e.g. cytomegalovirus or HIV infections);
- Hepatitis;
- Sarcoidosis;
- Collagenopathies;
- Cerebrovascular disorders (eg vasculitis);
- Central nervous system tumors (eg metastases secondary to lymphoma);
- Multiple sclerosis (demyelinating neurodegenerative disease).
Certain drugs that may also increase blood and urine concentrations of beta 2 microglobulin; these include:
- Lithium;
- Aminoglycoside antibiotics, cyclosporins and gentamicin;
- Cisplatin and carboplatin;
- Interferon-α;
- Radiographic contrast media.
