What is beta 2 microglobulin

Beta-2 microglobulin is a low-molecular-weight protein that forms the heavy chains component of class I histocompatibility (HLA: human leukocyte antigen) antigens. Beta-2 microglobulin is a protein that is found on the surface of almost all cells (nucleated cells) in your body and functions as part of the human immune system. Beta-2 microglobulin is routinely shed by cells, particularly by B lymphocytes and tumor cells, into the blood and is present in most body fluids, with highest levels in the blood, generally lower levels in cerebrospinal fluid (CSF), and trace levels in urine. Beta-2 microglobulin is present in most body fluids and its level rises with conditions that increase cell production and/or destruction, or that activate the immune system. Beta 2 microglobulin is frequently elevated in the blood with cancers such as multiple myeloma and lymphoma and with inflammatory disorders and infections (e.g., HIV, CMV). Because beta 2 microglobulin is increased with blood cell cancers, it may be useful as a tumor marker. The beta 2 microglobulin level can be increased in the cerebrospinal fluid (CSF) of individuals with blood cell cancers that have spread (metastasized) to the brain, such as lymphoma, but also with some chronic disorders such as multiple sclerosis and with viral infections such as HIV.

Beta 2 microglobulin can also be used to assess kidney function to distinguish between glomerular and tubular disorders of the kidney. In the kidneys, beta 2 microglobulin passes through blood-filtering units called the glomeruli and is then almost completely reabsorbed by the renal proximal tubules, structures that reclaim water, proteins, vitamins, minerals, and other vital substances. Normally, only small amounts of beta 2 microglobulin are present in the urine, but when the renal tubules become damaged or diseased, beta 2 microglobulin urine concentrations increase due to the decreased ability to reabsorb this protein. When the glomeruli in the kidneys are damaged, they are unable to filter out beta 2 microglobulin, so the level in the blood rises.

Increased levels of beta 2 microglobulin in the blood and/or urine indicate that there is a problem, but they are not diagnostic of a specific disease or condition. They do, however, reflect disease activity and the amount of cancer present. When someone has been diagnosed with multiple myeloma or lymphoma, that person is likely to have a poorer prognosis if the beta 2 microglobulin level is significantly elevated.

For monitoring treatment, decreasing levels over time in someone with multiple myeloma indicate that the person is responding to treatment. Stable or increasing levels indicate that the person is not responding.

Increases in the cerebrospinal fluid (CSF) in someone with a disease such as HIV/AIDS indicate likely central nervous system involvement.

Low levels of beta 2 microglobulin are considered normal. Beta 2 microglobulin may be undetectable in the urine and cerebrospinal fluid (CSF).

Beta 2 microglobulin test

Beta 2 microglobulin serum

Beta-2 microglobulin blood test is used as a tumor marker for some people with blood cell cancers. Beta-2 microglobulin serum test is not diagnostic for a specific disease, but it has been associated with the amount of cancer present (tumor burden) and can give a healthcare practitioner additional information about someone’s likely prognosis.

A blood beta 2 microglobulin test and sometimes a urine beta 2 microglobulin test may be ordered to help determine the severity and spread (stage) of multiple myeloma, to help evaluate the prognosis of cancers such as multiple myeloma and lymphoma, and may sometimes be ordered to evaluate disease activity and the effectiveness of treatment. Rarely, a cerebrospinal fluid (CSF) beta 2 microglobulin test may be used to determine whether there is central nervous system involvement. The utility of cerebrospinal fluid (CSF) beta 2 microglobulin in this circumstance remains unclear.

Elevated beta 2 microglobulin in the blood is correlated with a larger amount of tumor (tumor mass) and reduced kidney function in multiple myeloma patients. Recently, the International Myeloma Working Group published new guidelines called the International Staging System for Multiple Myeloma. The staging system is based mainly off of levels of both albumin and beta 2 microglobulin in the blood. Higher blood beta 2 microglobulin levels correspond with higher disease stages and therefore more advanced disease with worse prognosis.

What are tumor markers?

Tumor markers are substances, often proteins, that are produced by the cancer tissue itself or sometimes by the body in response to cancer growth. Because some of these substances can be detected in body samples such as blood, urine, and tissue, these markers may be used, along with other tests and procedures, to help detect and diagnose some types of cancer, predict and monitor a person’s response to certain treatments, and detect recurrence.

When is beta-2 microglobulin blood test ordered?

Beta-2 microglobulin serum test may be ordered during the initial workup of a person who has been diagnosed with multiple myeloma in order to stage the disease and periodically to evaluate disease activity and monitor the effectiveness of treatment. Beta-2 microglobulin serum test may sometimes be ordered when a person has myeloma or lymphoma to help determine their likely prognosis.

A cerebrospinal fluid (CSF) beta 2 microglobulin may rarely be ordered when a healthcare practitioner suspects that a disease such as lymphoma is affecting someone’s central nervous system.

Can I choose either a blood or a urine beta 2 microglobulin test?

In most cases, the sample tested will be dictated by the reason that the test is being performed. It may be necessary to do a blood test, a urine test, or both together. For staging of multiple myeloma, a blood test is preferred. Otherwise, it may be necessary to do a blood test, a urine test, or both together. In certain neurologic situations, cerebrospinal fluid (CSF) may also be tested. The results are not generally interchangeable.

Beta 2 microglobulin urine

The beta-2 microglobulin urine test may be used when known physical or suspected kidney damage occurs to distinguish between glomerular and tubular disorders of the kidney. Beta 2 microglobulin levels will also increase with disorders that involve overactive cell turnover and when the immune system is activated, thus is not diagnostic for a specific disease. With renal failure, it provides additional information about someone’s likely prognosis and the health of their kidneys. beta 2 microglobulin is measured in the following situations:

• In kidney disease, both blood and urine beta 2 microglobulin tests may be ordered along with other kidney function tests such as blood urea nitrogen (BUN), creatinine, and urine albumin (microalbumin) to evaluate kidney damage or disease and to distinguish between disorders that affect the glomeruli and the renal tubules.
• Used to monitor persons with end-stage renal disease (ESRD)
• Excess beta 2 microglobulin can accumulate in joint spaces (synovitis) in long-term dialysis patients; this is called dialysis-related amyloidosis. A beta 2 microglobulin test may be used to help evaluate a person for dialysis-related amyloidosis. People who have been on dialysis for five years or more may develop dialysis-related amyloidosis, a condition resulting from the accumulation of excess beta 2 microglobulin in the blood and eventually in the bone, joint, tendon (osteoarticular structure) and other body tissues such as heart, lung, and digestive tract. It is primarily diagnosed by tissue or bone biopsy. beta 2 microglobulin levels are performed as part of the work-up in addition to imaging studies.
• Beta 2 microglobulin tests may sometimes be ordered to monitor people who have had a kidney transplant to detect early signs of rejection.
• It may also be ordered to monitor people who are exposed to high levels of cadmium and/or other heavy metals like mercury, such as may occur with occupational exposure.

When is beta-2 microglobulin urine test ordered?

Both blood and urine beta 2 microglobulin tests may be ordered when a person has signs and symptoms associated with kidney dysfunction and a health practitioner wants to distinguish between disorders that affect the glomeruli and the renal tubules. Some signs and symptoms may include:

• Swelling or puffiness (edema), particularly around the eyes or in the face, wrists or ankles
• Urine that is foamy, bloody, pink or brownish
• Protein in the urine
• Fatigue, weakness
• Nausea

A beta-2 microglobulin urine test may also be ordered periodically to monitor a person who has had a kidney transplant or to monitor those exposed to high concentrations of cadmium or mercury to detect early kidney dysfunction.

If I have an elevated beta 2 microglobulin, does it mean that I have been exposed to cadmium or mercury?

Generally, no. It means that you may have some early kidney damage that affects your renal tubules. If you work with or suspect that you have been exposed to cadmium or mercury, then your doctor will order specific tests for cadmium or mercury in your blood and/or urine (see the article on Heavy Metals).

Beta 2 microglobulin normal range

• Beta 2 microglobulin in urine normal range: < or =300 mcg/L
• Beta 2 microglobulin in serum normal range: 1.21-2.70 mcg/mL
• Beta 2 microglobulin in cerebrospinal fluid (CSF) normal range: 0.70-1.80 mcg/mL

Recent nuclear medicine procedures and radiographic contrast media can affect test results.

Drugs such as lithium, cyclosporine, cisplatin, carboplatin, and aminoglycoside antibiotics can increase beta 2 microglobulin blood and/or urine concentrations.

Elevated beta 2 microglobulin

Levels of beta 2 microglobulin in the blood vary from low levels to four times the lower limit, and this is considered normal. Beta 2 microglobulin may be undetectable in the urine.

Increased levels of beta 2 microglobulin in the blood and urine indicate that there is a problem but are not diagnostic of a specific disease or condition.

Increases in blood and urine beta 2 microglobulin can be seen with certain cancers, including multiple myeloma, leukemia, and lymphoma. When there is central nervous system involvement, increased beta 2 microglobulin may also be found in the cerebrospinal fluid (CSF). Beta 2 microglobulin may also be present in infectious and cerebrovascular disorders. In cases of HIV, an inverse correlation between beta 2 microglobulin and CD4+ T-lymphocytes has been shown to mark disease progression.

Serum beta 2 microglobulin levels are elevated in diseases associated with increased cell turnover. Levels are also elevated in several benign conditions such as chronic inflammation, liver disease, renal dysfunction, some acute viral infections, and a number of malignancies, especially hematologic malignancies associated with the B-lymphocyte lineage. In multiple myeloma, beta 2 microglobulin is a powerful prognostic factor and serum beta-2-microglobulin values <4 mcg/mL are considered a good prognostic factor. In a study of pretreatment serum beta 2 microglobulin levels in 100 patients with myeloma it was reported that the median survival of patients with values >4 mcg/mL was 12 months, whereas median survival for patients with values <4 mcg/mL was 43 months.

In someone with signs of kidney disease, increased levels of beta 2 microglobulin in the blood and low levels in the urine indicate that the disorder is associated with glomeruli dysfunction. If beta 2 microglobulin is low in the blood and high in the urine, then it is likely that the person has proximal tubular renal damage or disease due to a variety of causes, including cadmium, mercury, lithium, or aminoglycoside toxicity; pyelonephritis; and Balkan nephropathy, a chronic interstitial nephritis of unknown cause. Increased beta 2 microglobulin urine excretion is consistent with renal tubular damage. Beta-2 microglobulin urine excretion is increased 100 to 1,000 times normal levels in cadmium-exposed workers. Increases in someone who is exposed to high levels of cadmium or mercury may indicate early kidney dysfunction. Although urine beta 2 microglobulin has been used to assess tubular dysfunction, it is not stable in urine below pH 5.5.

Also, beta 2 microglobulin levels correlate with risk of cardiovascular disease (CVD) and with cause of death in patients with kidney disease or on dialysis.

Beta 2 microglobulin is increased in patients with peripheral artery disease (PAD).

In people with kidney disease who are undergoing dialysis, beta 2 microglobulin can form long protein chains that can be deposited in joints and tissues, causing stiffness and pain. This condition is called beta 2 microglobulin dialysis-associated amyloidosis.

Increases in urine beta 2 microglobulin in a person with a kidney transplant may indicate early kidney rejection.

Increased beta 2 microglobulin levels in the cerebrospinal fluid (CSF) have been shown to be of diagnostic use in non-Hodgkin lymphoma with central nervous system involvement. Elevated CSF:serum ratios seen in patients with aseptic meningo-encephalitis suggest the possibility of neurologic processes including those associated with HIV infection and acute lymphoblastic leukemia. Beta 2 microglobulin measurement in multiple sclerosis seems to be of indeterminate usefulness.