Because symptoms of sarcoidosis
can mimic those of other diseases, in some cases sarcoidosis may be
diagnosed by excluding these other similar diseases. Frequently,
sarcoidosis is diagnosed because a routine chest x-ray shows an
abnormality. To make a diagnosis, most doctors will take a medical
history and perform a physical examination. The doctor also may need to
perform various tests and procedures to help diagnose sarcoidosis.
Some of the key tests to help monitor the disease during
and after treatment include:
Physical Examination: The doctor will
look for symptoms of the disease, such as red bumps on the skin, swollen
lymph nodes or redness in the eyes. The doctor also will check for
other possible causes of any symptoms.
Chest X-Ray: A chest x-ray, which poses
little risk to health, can detect sarcoidosis. X-ray beams cannot pass
as easily through granulomatous or scarred tissue as through normal
tissue. The x-ray may show granulomas, which appear as a shadow, or
enlarged lymph glands in the chest. Frequently, sarcoidosis is diagnosed
because a chest x-ray, taken routinely or for some other reason, shows
an abnormality. A staging system is used to classify chest x-rays
taken
to detect sarcoidosis.
- Stage 0 is a normal chest x-ray.
- Stage 1 is a chest x-ray with enlarged lymph
nodes but otherwise clear lungs.
- Stage 2 is a chest x-ray with
enlarged lymph nodes plus
infiltrates (shadows) in the lungs.
- Stage 3 is a chest x-ray that shows the
infiltrates (shadows) are present but the lymph nodes are no longer
seen.
- Stage 4 shows scar tissue in the lung tissue.
X-ray stages do not tell the severity of the
disease. However, in general the higher the stage of the x-ray, the
worse the person’s symptoms and lung function (as measured by
breathing tests). But there is a lot of individual variation, and
persons at Stages 0 through 3 may or may not have symptoms.
Blood Tests: Blood analyses evaluate the number
and types of blood cells in the body. The tests also measure the blood
levels of various proteins, such as angiotensin converting enzyme (ACE),
which are known to be involved in immunological activities, as well as
increases in calcium levels. ACE is made by cells in the granulomas.
However, ACE levels are not always elevated in those with the disease.
Blood tests can also show liver, kidney and bone marrow abnormalities
that can occur with sarcoidosis.
Pulmonary Function Tests: Pulmonary function
tests are used to monitor the course of the disease in the lungs. These
tests are safe and easy to do, but are frequently expensive. The results are compared over time. One
pulmonary function test uses a "spirometer" or a device that measures
how much and how fast a person can blow air out of the lungs after
taking a deep breath. This amount will be less than normal if there is
significant inflammation and/or scarring (or fibrosis) in the lung.
Another test measures lung volume, which indicates how much air the
lungs can hold. In some patients, the lungs may shrink or contract due
to sarcoidosis, and the lung volumes will be smaller than normal. Other
tests check for diffusing capacity, or how well a gas moves into the
bloodstream from the lungs. Sarcoidosis makes it harder for oxygen to
move from the lungs into the bloodstream. In one test, a device called a
pulse oximeter is placed on the finger to give the doctor a rough idea
of the level (or saturation) of oxygen in the patient’s blood. An
arterial blood gas test is a more accurate way to check the level of
oxygen in the bloodstream. Blood from an artery (usually in the wrist)
is used because it has passed through the lungs and taken up oxygen. The
blood is then analyzed for its oxygen and carbon dioxide levels. The
better the lungs are working, the more oxygen there will be in the
arterial blood.
Fiberoptic Bronchoscopy: In this procedure,
a long, narrow, flexible tube with a light at the end is inserted into
an airway of the lung. This makes it possible for the doctor to look at
the tissue lining the air passageways of the lungs. It is also possible
to use the bronchoscope to obtain small samples of lung tissue and to
obtain lung washings (or lavage) that contain lung cells from various
parts of the lungs.
Fiberoptic Bronchoscopy Biopsy: In this procedure,
a tiny sample of lung tissue is removed. The procedure is usually done to
make the diagnosis when pulmonary function tests or chest x rays are
abnormal and characteristic of sarcoidosis. If performed, it is done at
the time of a fiberoptic bronchoscopy. The test is done while the
patient is awake but slightly sedated. The test is usually very safe and
done on an outpatient basis.
Bronchoalveolar Lavage: Often, a procedure
called a bronchoalveolar lavage (BAL) is done as part of a fiberoptic
bronchoscopy. BAL involves injecting saline (salt water) into a region
of the lung. The fiberoptic bronchoscope then uses suction to remove the
fluid, which has washed out cells and other materials from the tiny air
sacs (or alveoli) of the lung. The pulmonary inflammation associated
with sarcoidosis begins in the lung in these air sacs. The removed
sample is examined for signs of inflammation and tested for infections
that may mimic sarcoidosis.
CT Scan: A computed tomographic (CT) scan is
a complicated kind of x-ray that gives a better picture of the lungs
than the ordinary chest x-ray. A CT scan may be done to better assess
how much of the lung is affected by sarcoidosis. CT scans are not
done routinely because they are more costly. Instead, they are done when
specific factors call for their need. CT scan of the lungs is important
if the patient is coughing up blood.
MR Scan: Magnetic resonance (also called nuclear
magnetic resonance, NMR scanning, or magnetic resonance imaging, MRI) uses powerful magnets and radio waves to see inside the
body. A computer generates images of the heart, brain and other organs.
The test is not invasive and has no known hazards. It can show if
features typical of sarcoidosis are present in organs, particularly the
brain and spinal cord.
Thallium and Gallium Scans: These scans are
used to help diagnose sarcoidosis and are often done to see if it is in
the heart. Thallium and gallium are radioactive elements. The doctor
injects one of these into a vein to help determine if the heart has been affected by sarcoidosis or another inflammatory
condition. At a specified time after the injection, the body is scanned
for radioactivity. Since any inflammation will cause an abnormal uptake of the
radioactive element, the test does not give a definitive diagnosis of
sarcoidosis.
PET Scans: Positron emission
tomography (PET) scanning detects changes in the body’s chemical
activities. As with nuclear imaging tests, you are injected with a
radioactive tracer, usually a kind of fluoride, before the test. It then
travels through the bloodstream, accumulating in areas that show
increased chemical activity. Since the parts of an organ that are not
functioning properly often show increased chemical activity, PET
scanning can help doctors determine whether an organ is healthy or
inflamed. It is often used to help diagnose cardiac sarcoidosis or to
find a good spot to biopsy.
Heart Tests: In addition
to the imaging techniques described above a number of other tests are
sometimes used to help diagnose cardiac sarcoidosis. Electrocardiography
and Holter monitoring are probably the simplest and most widely
available tools for initial evaluations of your heart rhythm. Heart
biopsies are invasive. They are rarely used today to diagnose cardiac
sarcoidosis.
Eye Tests: All persons diagnosed with sarcoidosis
should have an eye test done by an ophthalmologist (eye doctor), even if
there are no symptoms of the disease in the eyes. If eye symptoms appear,
the test will be repeated during treatment. Certain drugs can sometimes
cause side effects related to vision. (Refer to
the 'Treatment' section of this site
for more information on drugs used with sarcoidosis.) For the eye examination, the
doctor looks into the eye for abnormalities.
MONITORING THE DISEASE
Someone who is thought to have sarcoidosis should see their doctor
about the disease. Not all patients need to be seen by a doctor who
specializes in treating sarcoidosis. Referral to a specialist may be
helpful in complicated situations or to help plan treatment. (For more information on doctors who
treat sarcoidosis, see the 'Find
a Specialist' section of this site.)
Follow-up examinations may include a review of symptoms,
physical exams, chest x-rays and blood tests. How often these
tests are performed depends on the specific needs and symptoms of each
patient.
The preceding information relating to diagnosing sarcoidosis is drawn in part from the Department of Health and Human
Services, the National Institutes of Health and the National Heart Lung
and Blood Institute publication on Sarcoidosis. For more
information on NHLBI resources, visit the Links section of this
site. |