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Diagnosis | Systemic Lupus Erythematosus | SLE
What is Lupus?
Lupus is also known as the “disease of 1000 faces” because it can be very different from one person to another. The most common features of lupus are feeling tired and pain. But many other symptoms can be involved as well.
Lupus is best treated early to get the inflammation under control and help you live a more comfortable life. Chronic or long-lasting inflammation can cause a number of problems including heart disease. That’s why it’s important to treat lupus early.
What causes lupus?
Lupus is an autoimmune disease. For some reason the body’s immune system is “turned on” and begins to attack itself. When the immune system is turned on it makes you feel tired and achy. The best way to think of it is like you have the flu 24 hours a day 7 days a week. Except with lupus, you’re not fighting the flu.
Lupus causes the immune system to attack its own tissues. This attack produces inflammation. The word inflammation comes from the Latin word “inflammare” which means to light on fire. The tissues in the body are essentially “on fire.” In people with lupus, inflammation is extremely variable and can occur in almost any tissue of the body. The “fire” doesn’t have to be that hot – it can be a smouldering fire that slowly causes damage.
Who gets lupus?
Lupus is a disease that affects mostly young women of childbearing age. Sometimes, older women can develop lupus. The disease is about nine times more common in women than men. So it is really rare for a man to get lupus. People (usually women) typically develop lupus between the ages of 18 and 45 years.
It is estimated that about 1 in 1,000 people gets lupus. So, if you live in a city with 100,000 people then you could expect about 100 people to have lupus. So you can see that lupus is really not that rare. Some famous people with lupus include American Idol finalist Leslie Hunt, soap opera actress Kelly Drury, and Kelly Stone, sister of actress Sharon Stone.
It’s a common misconception that most cases of lupus are passed down through families. This is just not true. Most people (but not all) who develop lupus do not have a family member with the disease. However, genetics do appear to play a role in who gets lupus. That said, there are a few families that lupus runs in.
Think of lupus like a fire. To make a fire you need wood and something to light it with. Let’s think of the wood like it’s your genes. You need the right type of wood (nice and dry) to light a fire. Researchers have found that you need the right type of genes to light the fire of lupus. But that’s not the end of the story. You also need something to light the fire with. We’re not entirely sure what lights the fire of lupus. It might be the chemicals from cigarette smoke or a virus in the environment. Several triggers might be needed to light the fire. We just don’t know and it’s like looking for a needle in a haystack.
How is lupus diagnosed?
To properly diagnose lupus you need to be seen by a rheumatologist or other specialist who knows about the disease. Lupus can be tricky to diagnose and having someone experienced is very useful.
The first thing that should happen is the specialist should take a very thorough history. They should ask you lots and lots of questions because lupus can have so many symptoms. Following this, a complete physical examination should be performed including your head and neck, lungs, heart, abdomen, joints, and skin.
Finally, special blood tests are ordered to see if your body is making antibodies to itself.
What tests are done to diagnose lupus?
Anti-Nuclear Antibody (ANA) Test
The most important blood test to do first if someone thinks you have lupus is the anti-nuclear antibody test (this is also known as the ANA). This test looks to see if your body is making antibodies to itself. Now, believe it or not, we all make antibodies to ourselves. It’s normal to do this but you don’t want to make too many antibodies or have them attacking in unusual places. The ANA test gives two results: (a) the titre and (b) the pattern.
(a) The Titre: The titre tells you how many antibodies you have. It starts out at 1:40 and then increases through the following levels 1:80, 1:160, 1:320, 1:640, 1:1280, 1:2560. In most labs the highest level is 1:2560. If your levels are 1:40-1:160 these are pretty low and might actually be normal. The level of 1:320 is the “cusp” which is more likely to mean something. Levels of 1:640, 1:1280, and 1:2560 are more concerning. Ask your doctor what your titre is. An important point: It isn’t that useful to keep measuring the titre as it does not go up and down as your disease gets better or worse.
(b) The Pattern: There are a number of patterns to the ANA including homogenous, speckled, nucleolar, centromere, rim enhancing. Homogenous is the most common and least concerning pattern.
It is fairly safe to say that if your ANA is negative then you don’t have lupus.
If the ANA is positive then other tests are done. Think of it like this – looking for ANA is like looking for fish in a lake. Lets say we take a trip down to the lake, jump in our boat, and grab our handy fish finder. Lets say we go all over the lake looking everywhere for fish. There are a few possibilities: (1) We only see a few fish or none at all or (2) we see loads of fish. Ok, if we don’t see any fish then chances are if we keep going down to the lake looking for fish every weekend we aren’t going to find tons of fish. So if the ANA is negative (we don’t see fish) it isn’t necessary to keep testing it. If it is only low positive 1:40, 1:80, 1:160 don’t keep testing it. In fact, you really don’t have to ever keep testing the level (titre) of the ANA (as said above)
On the other hand, lets say we see loads of fish. The first question to ask is what type of fish are they? Are they minnows or sharks or pirrhana? Same thing with the ANA – if we see loads of autoantibodies the next question to ask is what type of antibodies they are? So if the ANA is really positive (1:320, 1:640, 1:1280, 1:2560) then you need to look at what type of antibodies they are. The two tests we use include the anti-double stranded DNA (anti-dsDNA) and the ENA panel.
Anti-Double Stranded DNA (anti-dsDNA)
This test measures antibodies that attack DNA. DNA is the protein that makes up your genes. The thing to remember is that the anti-dsDNA is very specific test for lupus. What this means is if this test is very positive then it is very likely that this is lupus. However, if the test is negative it does not mean you have lupus.
Extractable Nuclear Antigen (ENA) Panel
This is a test that measures antibodies to 6 or 7 other proteins in the body. The antibodies in this panel may include: anti-Ro (also called anti-SSA), anti-La (also called anti-SSB), anti-Sm, anti-RNP, anti-Jo-1, anti-Scl70, and anti-centromere. Things get a bit more tricky here and its best to discuss this with your rheumatologist.
Read more – Symptoms of Systemic Lupus Erythematosus