How do we diagnose systemic lupus (SLE)?
I see many patients in my practice who have a result in their blood test which is positive called ‘ANA”. This is known to be a blood marker for what is generically referred to as ‘lupus’.
People come to see me questioning whether they have lupus because their blood test is positive and also thinking that they have lupus and having been diagnosed as having lupus because their blood marker for lupus is positive.
However, making a diagnosis of lupus is more than one blood test result. It is a difficult disease to diagnose and a clinical diagnosis is more important than isolated blood test results.
Its also important to be precise when we are using the term ‘lupus’ as there are two different types of Lupus. One is systemic lupus, referred to as SLE because it stands for Systemic Lupus Erythematosus, and the other one is cutaneous lupus.
SLE, systemic lupus, is a disease where many organ systems are affected and this can adversely affect the length and quality of life. Whereas instead, cutaneous lupus is disease limited only to the skin, with different treatment requirements and a more mild condition than SLE. Both of them can have a positive ANA.
Thus it is really important to confirm the correct diagnosis.
Seeing a Rheumatologist is vital to make the diagnosis of systemic lupus. It can be a disease that is in evolution taking time for more symptoms to evolve. And there can be many other conditions that cause similar symptoms that need to be ruled out first.
When I see people with a possibility of systemic lupus I make sure to do a complete and thorough evaluation. If the immune marker ANA is positive, that is one thing I look at.
The next thing to look at is the pattern of the immune marker as some patterns of the immune marker ANA are NOT associated with systemic lupus or any other autoimmune connective tissue disease.
The really important thing that I do is speak to the person seeing me to get a full understanding of what is going on in their body and what they are concerned about. It is a full system review to see if for example there are any rashes, if there is fatigue, are there any symptoms of any other organ dysfunction such as breathing issues, joint pains or joint swellings and if so where, as the pattern of joint involvement is really important.
Many people see me who have fatigue and a positive ANA. This does not mean that systemic lupus is the cause of the fatigue as fatigue can be caused by many factors.
To make a diagnosis of systemic lupus there need to be at least FOUR features of the disease that have been recognised by rheumatologists. This can include blood markers but also clinical features.
It is a disease with wide and varied features and it can masquerade as so many other conditions that need to be excluded before a diagnosis of Systemic Lupus can be confirmed.
Symptoms that we look for are:
· Raynauds disease – where the circulation shuts down in hands and or feet, giving white or red/blue tips of digits,
· mouth or nasal ulcers, usually painless,
· rash – usually sensitive to light or sun,
· alopecia where there are bald patches, or diffuse thinning with fragile broken hairs
· arthritis – where there is swelling in the joints, usually symmetrical
· pain on breathing or chest pain suggesting inflammation of the lining of the lungs or heart
· have there been any seizures or is there any type of psychosis – this can suggest brain involvement. Is there numbness/altered sensation or weakness – suggesting potential nerve involvement
These symptoms don’t just occur in systemic lupus.
This is why its important to be seen by an experienced Rheumatologist when you are considering a possible diagnosis of SLE to make sure that nothing else has been missed. You do not want to be on treatment for the wrong condition.
Making a diagnosis means talking to understand your symptoms in full, being examined to see if you have signs of the disease and then investigations.
The investigations done depend on what your symptoms are and what the possible other diagnoses are. Once preliminary investigations have been done, more tests may be ordered if there are abnormalities, again depending on where your symptoms are and what the tests are showing.
Initially blood tests are done, looking for inflammation markers and tests looking for markers of active systemic lupus such as ds DNA and C3 and C4. Looking for evidence of kidney involvement with urine testing looking for blood and protein, Other bloods are done to check general organ function such as the bone marrow, kidneys and liver, and other immune markers as indicated.
X-rays and other radiological imaging will be done, depending on what your symptoms are, and what other diseases are being eliminated.
· This may include a chest Xray or a CT of your chest, abdomen and pelvis.
· Joints that are affected may be x-rayed or imaged by MRI looking for evidence of bone and joint damage.
· You may have an ECG or ultrasound of the heart (known as an echocardiogram) if your symptoms suggest inflammation of the lining of the heart, which is known as ‘Pericarditis.
If there is evidence of other organ dysfunction, you may even need to have an organ biopsy such as a kidney biopsy or a bone marrow biopsy depending on what your initial test results show.
Systemic lupus is usually managed and diagnosed by a Rheumatologist. However, you may also be referred to other specialists for assessment depending on your symptoms and results of preliminary tests. For example, if the kidneys appear to be involved a kidney specialist – Nephrologist, will be involved with your diagnosis and then your care if there are signs of involvement.
If you are concerned that you may have lupus its important to see a Rheumatologist for a full and thorough evaluation.