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| Detailed Guide: Multiple Myeloma |
How is Multiple Myeloma Diagnosed? |
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If symptoms suggest that a person may have multiple myeloma, laboratory
tests on the blood and/or urine, x-rays of the bones, and a bone marrow
biopsy are usually done.
Laboratory Tests of Blood and Urine
The blood and/or urine can be examined for an abnormal immunoglobulin
(or antibody) that may build up to high levels in the blood. Often,
parts of this protein are excreted by the kidneys into the urine.
Finding the abnormal immunoglobulin in the blood and/or urine can help
determine whether a plasma cell tumor is present. These abnormal
proteins have several names, including monoclonal immunoglobulin,
M protein, M spike, and paraprotein. Any
amount of this protein is abnormal, but it usually it increases as the
disease progresses. The procedures used for finding a monoclonal
immunoglobulin are laboratory techniques known as serum protein electrophoresis
(SPEP) and urine
protein electrophoresis (UPEP). The presence of high
levels of another protein, beta-2-microglobulin, may also indicate that
myeloma is present, although this protein is elevated in the blood in
other diseases of immune cells such as lymphoma.
Bone Marrow Biopsy
A bone marrow biopsy
and aspiration
(removing a sample of the inside of the bone with a needle) can be done
to confirm a diagnosis of multiple myeloma. A doctor will use a
microscope to look at the bone marrow tissue to determine if there are
myeloma cells in the bone marrow and, if so, how many.
In this procedure, the back of the pelvic bone is numbed with local
anesthetic. Then a biopsy needle is placed into the bone and used to
remove a cylindrical piece of solid bone and some marrow that is about
1-inch long and 1/16-inch in diameter. After this some bone marrow is
sucked up into a syringe. The aspirate (material removed by suction)
contains a few drops of fluid and tiny fragments of marrow. If there is
a single tumor (plasmacytoma), a biopsy may be taken there.
Imaging Studies
Bone X-rays
Bone destruction caused by the myeloma cells can be detected with
x-rays. Often doctors will do x-rays of most of the bones, particularly
in the arms and legs where there is the possibility of fractures. A
more detailed imaging study, either a CT scan or an MRI scan (see
below), may locate bone destruction caused by the tumor before it is
seen by x-ray examination.
Computed tomography (CT):
The CT scan (also known as a CAT scan) is an x-ray procedure that
produces detailed cross-sectional images of your body. Instead of
taking one picture, like a conventional x-ray, a CT scanner takes many
pictures of the part of your body being studied as it rotates around
you. A computer then combines these pictures into an image of a slice
of your body. Sometimes, this test can help tell if your bones have
been damaged by the myeloma.
Often after the first set of pictures is taken you will receive an
intravenous injection of a radiocontrast
agent, or dye. This helps better outline structures in
your body. A second set of pictures is then taken. The injection can
cause some flushing (a feeling of warmth, especially in the face). Some
people are allergic and get hives, or rarely, more serious reactions
like trouble breathing and low blood pressure. Be sure to tell the
doctor if you have ever had a reaction to any contrast material used
for x-rays. If you are receiving contrast material, it is important you
tell the people injecting the material that you are diagnosed with
myeloma. Some of these contrast agents can damage the kidneys of people
with myeloma.
CT scans are more tedious than regular x-rays because they take longer
and you usually need to lie still on a table a while they are being
done. But just like other computerized devices, they are getting faster
and your stay might be pleasantly short. Some modern scanners can
complete the study in seconds. Also, you might feel a bit confined by
lying within the equipment while the pictures are being taken.
CT scans can also be used to guide a biopsy needle precisely into a
suspected bone tumor. For this procedure, called a CT-guided needle biopsy,
the patient remains on the CT scanning table while a radiologist
advances a biopsy needle toward the location of the tumor. CT scans are
repeated until the doctors are confident that the needle is within the
mass. A fine needle biopsy sample (tiny fragment of tissue) or a core
needle biopsy sample (a thin cylinder of tissue about ½-inch long and
less than 1/8 inch in diameter) is removed and examined under a
microscope.
Magnetic resonance
imaging (MRI): MRI scans use radio waves and strong
magnets instead of x-rays. The energy from the radio waves is absorbed
and then released in a pattern formed by the type of tissue and by
certain diseases. A computer translates the pattern of radio waves
given off by the tissues into a very detailed image of parts of the
body. Not only does this produce cross-sectional slices of the body
like a CT scanner, it can also produce slices that are parallel with
the length of your body. A dye (contrast material) might be injected
just as with CT scans but is used less often.
MRI scans are very helpful in looking at bones. MRI scans are a little
more uncomfortable than CT scans. First, they take longer -- often up
to an hour. Also, you have to be placed inside tunnel-like equipment,
which is confining and can upset people with claustrophobia. The
machine also makes a thumping noise that you may find disturbing. Some
places provide headphones with music to block this out.
Positron emission
tomography (PET): This is a type of radioactive scan. With
a PET scan, the patient is given an injection of radioactive sugar
(glucose). Cancer cells absorb high amounts of the radioactive sugar
because of their high rate of metabolism. A special camera can detect
the radioactivity. There have been few studies of PET scans in myeloma,
but some studies find this might be useful in certain situations,
mainly plasmacytomas, to look for other plasmacytomas or myeloma.
Blood tests:
Certain blood tests are important in assessing patients with myeloma,
even if they are not essential to the diagnosis.
- Hemoglobin
level: This is a measure of the red cell production by the
bone marrow. A low level is called anemia and can lead to symptoms such
as fatigue and shortness of breath with activity.
- Platelet
count: Platelets help seal damaged blood vessels. A low
platelet count may lead to excessive bruising and bleeding, although
this is uncommon. But, a low platelet count indicates that the myeloma
is spread widely through the bone marrow, the site of platelet
production.
- Beta-2
microglobulin: High levels indicate more advanced disease
and may indicate a worse prognosis.
- Serum albumin:
Another important test. Low levels indicate advanced disease.
- Serum calcium:
This can be elevated in people whose myeloma is advanced. It can cause
severe symptoms of fatigue and weakness. (See above).
- Serum BUN and
Creatinine: These are tests of kidney function, which can
be impaired in people with myeloma. If they are abnormal, that is
another signs of more advanced disease.
Interpretation of Test Results
Results of any single test are not enough to make a diagnosis of
multiple myeloma. Diagnosis is based on a combination of factors,
including the patient's description of symptoms, the doctor's physical
examination of the patient, and the results of blood tests and x-rays.
The diagnosis of multiple myeloma requires that a patient with symptoms
have at least 1 major criterion or at least 3 minor criteria from the
list below:
Major criteria:
- A biopsy result shows a plasma cell tumor.
- Over 30% of cells in the bone marrow sample are plasma
cells.
- The monoclonal immunoglobulin in the blood or urine exceeds
a certain amount.
Minor criteria:
- Between 10% and 30% of cells in the bone marrow sample are
plasma cells.
- A monoclonal immunoglobulin is found but not enough is
present to fulfill a major criterion.
- Holes in bones due to tumor growth are found on imaging
studies.
- The amount of normal antibody (not produced by the cancer
cells) in the blood is abnormally low.
Revised: 08/04/2006
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