How Is Sarcoidosis Diagnosed?
Your doctor will find out if you have
sarcoidosis by taking a detailed medical history and conducting a physical exam
and several diagnostic tests. The purpose is to:
- Identify the presence of granulomas in any of
your organs
- Rule out other causes of your symptoms
- Determine the amount of damage to any of your
affected organs
- Determine whether you need treatment.
Medical History
Your doctor will ask you for a detailed
medical history. He or she will want to know about any family history of
sarcoidosis and what jobs you have had that may have increased your chances of
getting sarcoidosis.
Your doctor may also ask whether you
have ever been exposed to inhaled beryllium metal, which is used in aircraft
and weapons manufacture, or organic dust from birds or hay. These things can
produce granulomas in your lungs that look like the granulomas that are caused
by sarcoidosis but are actually signs of other conditions.
Physical Exam
Your doctor will look for symptoms of
sarcoidosis, such as red bumps on your skin; swollen lymph nodes; an enlarged
liver, spleen, or salivary gland(s); or redness in your eyes. He or she will
also listen for abnormal lung sounds or heart rhythm. Your doctor also will
check for other likely causes of your symptoms.
Diagnostic Tests
There is no one specific test for
diagnosing sarcoidosis. It is harder to diagnose sarcoidosis in some organs
(e.g., heart, nervous system) than in others. Your doctor will probably conduct
a variety of tests and procedures to help in the diagnosis.
These include:
- Chest X Ray. A chest x ray takes a picture
of your heart and lungs. It may show granulomas or enlarged lymph nodes in your
chest. About 95 out of every 100 people who have sarcoidosis have an abnormal
chest x ray.
- Doctors usually use a staging
system for chest x rays taken to detect sarcoidosis:
- Stage 0: Normal chest x ray
- Stage 1: Chest x ray showing enlarged lymph
nodes but otherwise clear lungs
- Stage 2: Chest x ray showing enlarged lymph
nodes and shadows in your lungs
- Stage 3: Chest x ray showing shadows in your
lungs, but the lymph nodes are not enlarged
- Stage 4: Chest x ray showing scars in the
lung tissue.
In general, the higher the stage of the x ray,
the worse your symptoms and lung function are. But there are a lot of
differences among people. If your x-ray results show Stages 0, 1, 2, or 3, you
may not have symptoms or need treatment, and you may get better and have normal
chest x rays again over time.
- Blood Tests. These tests can show the
number and type of cells in your blood. They also will show whether there are
increases in your calcium levels or changes in your liver, kidney, and bone
marrow that can occur with sarcoidosis.
- Lung Function Tests. One test uses a spirometer
(spi-rom'e-ter), a device that measures how much and how fast you can blow air
out of your lungs after taking a deep breath. If there is a lot of inflammation
and/or scarring in your lungs, you will not be able to move normal amounts of
air in and out.
- Another test measures how much
air your lungs can hold. Sarcoidosis can cause your lungs to shrink, and they
will not be able to hold as much air as healthy lungs.
- Electrocardiogram (EKG). This test will
help show if your heart is affected by sarcoidosis.
- Pulse Oximetry. A small clip attached to
your finger tip can show how well your heart and lungs are moving oxygen into
your blood.
- Arterial Blood Gas Test. This test is more
accurate than pulse oximetry for checking the level of oxygen in your
bloodstream. Blood is taken from an artery (usually in your wrist). It is then
analyzed for its oxygen and carbon dioxide levels.
- Fiberoptic Bronchoscopy. In this procedure, your doctor
inserts a long, narrow, flexible tube with a light on the end through your nose
or mouth into your lungs to look at your airways. This tube is called a
bronchoscope. You most likely would have this procedure as an outpatient in a
hospital under local anesthesia.
- Bronchoalveolar Lavage (brong"ko-al-ve'o-lar
lah-vaje') (BAL). During bronchoscopy, your doctor may inject a small
amount of salt water (saline) through the bronchoscope into your lungs. This
fluid washes the lungs and helps bring up cells and other material from the air
sacs deep in your lungs where the inflammation usually starts to develop. The
cells and fluid are then examined for signs of inflammation.
- Biopsy. Your doctor may take a small
sample of tissue from one of your affected organs. For example, when breathing
tests or chest x rays show signs of sarcoidosis in your lungs, your doctor may
do a fiberoptic bronchoscopy biopsy. This will help confirm the diagnosis. Your
doctor inserts a tiny forceps through the bronchoscope to collect tissue that
will be examined. Because the granulomas may be spread out in your lungs, the
bronchoscope may miss some of them.
- Biopsies of your skin and liver
are sometimes done to detect granulomas in these organs.
- You may have sarcoidosis in
other organs as well and multiple biopsies may be necessary. However, every
organ involved does not need to be biopsied for a diagnosis to be made.
- Computerized Tomography (CT) Scan. This
test provides a computer-generated image of your organs that has more detail
than a regular chest x ray. It can provide more information about how
sarcoidosis has affected an organ.
- Your doctor may do a CT scan to:
- Obtain more information about how much of
your lung is affected by sarcoidosis.
- Detect sarcoidosis in your liver. A CT scan
of your abdomen will show if your liver is enlarged and if there is a pattern
suggesting granulomas.
- Magnetic Resonance (MR) Scan. This test is
also called nuclear magnetic resonance (NMR) scanning or magnetic resonance
imaging (MRI). This scan uses powerful magnets and radio waves to make images
of some of your organs that your doctor doesn't want to risk doing a biopsy on.
For example, an MR scan can be used to diagnose sarcoidosis in your brain,
spinal cord, nerves, or heart.
- Thallium and Gallium Scans. These scans
are often done to see if sarcoidosis is affecting your heart. Thallium and
gallium are radioactive elements. Your doctor injects a small amount of one of
them into a vein in your arm. The elements collect at places in your body where
there is inflammation. After awhile, your body is scanned for radioactivity.
Increased radioactivity at any place may be a sign of inflammation.
- This test gives information on
the tissue in your body that has been affected by sarcoidosis and the amount of
damage to it. But since this test shows all inflammation in your body, even
inflammation caused by conditions other than sarcoidosis, it does not give a
definite diagnosis of sarcoidosis.
- Positron Emission Tomography (PET) Scan.
This test also uses radioactive injections. It may be more sensitive than
gallium in detecting areas of inflammation. Some doctors are using it instead
of gallium scans.
Your doctor may not need to find every
one of your organs affected by sarcoidosis, only those that cause symptoms.
Often the organs affected by the condition continue to function well and don't
need to be treated.
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