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Drug Induced Lupus
|How Is Lupus Diagnosed?
There is no single test for lupus. Lupus is a difficult disease to diagnose because it does not develop rapidly. Rather it develops slowly; symptoms come and go and it takes time for enough symptoms to cluster to indicate the presence of a disease. Things are further complicated by the fact that lupus is a great imitator. It mimics the symptoms of many other conditions such as fibromyalgia, rheumatoid arthritis, thyroid disease and Lyme disease. Given these challenges, a lupus diagnosis requires review of:
1. Your current symptoms, see common symptoms of lupus.
2. Your medical history.
3. The medical history of your family, do any close family members (parents, grandparents, brothers, sisters, aunts or uncles) have lupus, or any other autoimmune disease?
4. Your laboratory test results.
In essence, a diagnosis is more of an educated guess because laboratory tests alone cannot give a definite yes or no answer. For example, a positive blood test that suggests lupus may be due to some other illness, or can even be seen in healthy people.
What Tests Are Done?
Your doctor will perform different laboratory tests to detect changes in your body. Each test result will help build up a picture about your condition.
1. Blood Test
First a blood test will be done to perform a complete blood count (CBC). If you have lupus, you may have low numbers of red blood cells, white blood cells or platelets. Read more about the composition of blood.
2. Urine Test
You will need to provide a sample of urine. This will be used to check that your kidneys are working properly. Lupus can quietly attack the kidneys without causing any obvious symptoms. The lab will look for levels of proteinuria in your urine. These are proteins which spill into urine when the kidneys are not filtering waste properly.
3. Antibodies Test
Antibodies are a substance your body make, they attack your own tissues causing inflammation and lupus (read more about the causes of lupus). A panel, or group of blood tests will be ordered to test for specific antibodies. These include:
Antinuclear antibodies (ANA): These antibodies bind to the command center of cells in the body and destroy them. ANA are found in 95 percent of people with lupus. If three or more symptoms of lupus are present - such as skin rash, joint pain and kidney problems - a positive ANA test will result in a lupus diagnosis.
Antibodies to double-stranded DNA (anti-dsDNA): These antibodies attack the DNA of cells. They are found in about 50 percent of people with lupus. However, lupus can still be present even if anti-dsDNA is not present.
Antibodies to histone: This is a type of protein that surrounds DNA molecules in cells. It is sometimes found in people with systemic lupus, but more commonly in those with drug-induced lupus. Drug induced lupus is caused by taking certain medications and usually goes away after stopping the medication.
Antibodies to phospholipids (aPLs) or antiphospholipid antibodies: These antibodies cause blood vessels to narrow and can lead to strokes, heart attacks, blood clots in the legs or lungs and miscarriages. About 30 percent of people with lupus have aPLs.
Antibodies to Ro/SS-A and La/SS-B: Anti-Ro antibodies are likely to be found in people with skin lupus that causes a rash when exposed to the sun. If you are pregnant it is important to test for the presence of these antibodies because they can cross the placenta and cause neonatal lupus. Neonatal lupus is rare, but it can lead to serious heart complications.
Antibodies to Sm target Sm: The presence of this antibody almost always means you have lupus. Only 30 to 40 percent of people with lupus have it.
Antibodies to RNP target ribonucleoproteins (Anti-RNPs): Anti-RNPs are high in people with all types of autoimmune conditions, including lupus.
4. Additional Blood Tests
Complement: Complement is a group of proteins that help fight infections. Many of the proteins are used up when the body becomes inflamed due to lupus. Low levels may indicate lupus.
C-reactive protein (CRP): Raised levels of CRP in your blood can indicate inflammation in the body. See, c-reactive protein test.
Erythrocyte sedimentation rate (ESR or "sed" rate): Measures the amount of protein it takes for blood to clot. The rate is usually high in people with active lupus.
Blood clotting test: How fast your blood begins to clot is important. If it clots too quickly it raises your risk of fatal blood clots.
A tissue biopsy of the kidneys or other organs may be done to check for signs of damage due to inflammation. The skin and kidneys are the most common sites for biopsy.
A chest x-ray may be done to see if fluid has collected around the lungs in those complaining of chest pain.
What Kind Of Doctor Diagnoses Lupus?
Most patients start with their family doctor but are eventually referred to a rheumatologist for diagnosis.
Where Is The Best Place To Get Diagnosed?
There is no one center of excellence for the treatment and diagnosis of lupus in the United States. Instead the Lupus Foundation of America recommends finding a doctor that is affiliated with a medical school or university hospital. These facilities have staff that are involved in lupus research and will be up to date both on the diagnosis and treatment of lupus.