Those of you who have Lupus or those of you who know loved ones who have Lupus, know it can be very difficult to diagnose Lupus. It can take months or even up to years to diagnose Lupus.
It is difficult for a number of reasons:
- Systemic lupus is a multi-system disease, and before a multi-system disease can be diagnosed, there have to be symptoms in many parts of the body and lab work that supports the presence of a multi-system disease.
- Systemic lupus is also difficult to diagnose because it is a disease that does not typically develop rapidly, but rather develops slowly and evolves over time. Symptoms come and go and it generally takes time to gradually accumulate enough symptoms to indicate that a multi-system disease is present.
- Systemic lupus is known as a Great Imitator because it mimics so many other diseases and conditions. (which I'll talk about in my next blog)
- Systemic lupus is difficult to diagnose because there is no single diagnostic test for lupus. In fact, many people may have positive lupus tests-particularly the anti-nuclear antibody test-and yet NOT have the disease.
How is systemic lupus diagnosed?
Physicians have to gather information from a
variety of sources: past medical history, lab tests and current symptoms. They
use a list of 11 criteria to
help diagnose SLE. A person needs to satisfy at least 4 out of the 11 criteria
before the diagnosis can be pinpointed. Some criteria, such as a biopsy
diagnosis of kidney lupus, can carry more weight.
Of the 11 criteria, 7 relate to symptoms, and
4 have to do with lab tests. The ANA test is
used as a screening test for systemic lupus. We know that 95 % of people with
SLE have a positive ANA. Therefore, if a person has many symptoms of systemic
lupus and their ANA test is negative, that's generally regarded as pretty good
evidence against lupus being the explanation for the symptoms they are having.
If on the other hand, the ANA comes back
positive, that IS NOT proof of lupus. The positive ANA is only an indicator; it
is not diagnostic. A positive ANA can be found in a number of illnesses and
conditions including:
Autoimmune diseases including:
Rheumatoid arthritis
Sjogren's (show-grens) syndrome
Scleroderma (sklare-a-derm-a)
Infectious diseases such as:
Mononucleosis
Malaria
Subacute bacterial endocarditis (SBE)
Autoimmune diseases including:
Autoimmune thyroid disease
Autoimmune liver disease
Malaria
Subacute bacterial endocarditis (SBE)
Autoimmune diseases including:
Autoimmune thyroid disease
Autoimmune liver disease
Certain medications can also cause a positive
ANA. About 20% of the general population when tested will have a positive ANA
and not have any of the above mentioned illnesses. The ANA is only a test and
like a high cholesterol value, a positive ANA doesn't necessarily equate having
a disease.
So, a positive ANA, by itself, is not diagnostic of
any one particular disease and may be present in people who have no illness.
Although it is often referred to as "a lupus test," it is not like a
pregnancy test where a positive result can mean only one thing. The ANA is only
an indicator, which points in several possible directions. A positive ANA
satisfies only one criterion. A person would need to satisfy at least 3
additional criteria. See: Laboratory Tests Used in the Diagnosis of Lupus
Because many symptoms of systemic lupus erythematosus
(SLE) mimic those of other illnesses, lupus can be a difficult disease
to diagnose. Diagnosis is usually made by a careful review of three
factors:
- the individual's entire medical history
- an analysis of the results obtained in routine laboratory tests and
- some specialized tests related to immune status.
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