ApprovedLFA Patient Education Committee
92-035
Research focusing on the nature of lupus (SLE) has accelerated sharply over the past twenty years. It is believed that the symptoms of lupus are the result of an abnormally functioning immune system. What causes the malfunction is not yet known. The normal immune system functions to protect the body against damage by viruses, bacteria and other foreign substances.
In lupus, this same immune system appears to react against the body's own healthy cells forming antibodies against them. This causes inflammation and the subsequent symptoms of the disease. Since the immune system functions throughout the body, the symptoms of lupus can vary widely in type and intensity, depending on the parts of the body being affected.
Why is it difficult?
Most people involved in lupus research and treatment would probably agree that lupus still remains a difficult disease to diagnose. Two reasons account for this difficulty:
There is no single set of symptoms that are uniformly specific to lupus.
There are no laboratory tests yet available that can prove conclusively that a person has or does not have lupus. Almost every symptom of lupus can also be easily attributed to other illnesses or disorders. In addition, the symptoms are sometimes vague or they may come and go spontaneously.
For instance, fever, weight loss, marked fatigue and weakness which are often experienced by someone with lupus, may also be symptoms of many others disorders, some more threatening, some less so.
Likewise if transient (temporary) joint or muscle pain is the initial problem, here again there are so many causes of such symptoms that it may be very difficult to link these to lupus. If pleurisy is a symptom and it spontaneously clears up rather quickly, the physician may assume that a virus was the cause and not necessarily lupus.
Approach to diagnosis
The diagnosis of lupus is usually made after a careful review of the patient's medical history, coupled with analysis of blood study results from both routine laboratory testing and some specialized tests related to immune system status. Since symptoms may present themselves slowly and may evolve over months or years, it is important that a physician follow the patient to see what happens.
Often it can take years for the diagnosis to be made. This can be a very difficult time for the person seeking relief from numerous symptoms. Only by a comprehensive examination can the probability of lupus be assessed and even then it is sometimes very difficult to be sure.
Evaluation of symptoms
The first principle in making a diagnosis of SLE is that the individual has clinical evidence of a multi-system disease (i.e. has shown abnormalities in several different organ systems). The following are typical manifestations (symptoms) which might lead to suspicion of SLE.
- Skin: butterfly rash; ulcers in the roof of the mouth; hair loss.
- Joints: pain; redness and swelling.
- Kidney: abnormal urinalysis suggesting kidney disease.
- Lining membranes: pleurisy; pericarditis and/or peritonitis (taken together this type of inflammation is known as polyserositis).
- Blood: hemolytic anemia (the red cells are destroyed by autoantibodies); leukopenia (low white blood cell count);thrombocytopenia (low platelets).
- Lungs: infiltrates that may be transient.
- Nervous system: convulsions (seizures); psychosis; nerve abnormalities that cause strange sensations or alter muscular ability.
Evaluation of immune status
The second diagnostic principle is to examine the status of the immune system in individuals having a suspicious clinical history. In general, physicians now look for evidence of autoantibodies.
At this time some commonly used tests of immune status in the diagnosis of SLE are:
The anti-nuclear antibody test (ANA): a test to determine if autoantibodies to cell nuclei are present in the blood.
The anti-DNA antibody test: to determine if the patient has antibodies to the genetic material in the cell. The anti-Sm antibody test: to determine if there are antibodies to this substance, a nuclear protein. A variety of tests for the presence of immune complexes in the blood.
Tests to examine the total level of serum complement - a group of proteins involved in the inflammation which can occur in immune reactions - and tests to assess the specific level of C3 and C4, two proteins of this group.
LE cell prep: An examination of the blood looking for a certain kind of cell which has ingested the swollen antibody-coated nucleus of another cell. A positive ANA may occur sometime during the course of the illness in about 90 percent of patients with SLE, but it also occurs in a variety of other illnesses and in as much as 5 percent of the normal population. It is a very sensitive test and is now more frequently performed than the LE prep.
Tissue biopsy
Sometimes examination of a tissue sample can be helpful in making the diagnosis. A kidney biopsy, for example, can show certain changes characteristic of SLE if the kidney disease is severe. Even in early kidney involvement, examination of biopsy tissue can show deposits of antibodies and immune complexes in the kidney's filtration unit.
A skin biopsy can be helpful in identifying deposits of antibodies and complement proteins found at the junction of the outer skin layer, called the epidermis, and the underlying part of the skin, the dermis. A "positive band test" is significant only when the tissue sample is taken from an area which is not involved by the rash. The results, like those of a kidney biopsy, should be interpreted in combination with the clinical history, as well as all the other tests performed.
Criteria
In 1982, the American Rheumatism Association published a revised set of criteria to aid physicians in making the diagnosis of Lupus. The criteria (see note) are:
- Malar Rash
- Discoid Rash
- Photosensitivity
- Oral Ulcers
- Arthritis
- Serositis
- Renal disorder
- Neurologic disorder
- Hematological disorder
- Immunologic disorder
Positive fluorescent antinuclear antibody (FANA) or ANA test result A physician observing a person to have at least 4 out of the 11 criteria, either serially or collectively, should be suspicious to the possibility of lupus being the underlying disorder. However, physicians must also be careful in utilizing criteria for an individual case, as other diseases could also conform to the criteria.
Presently, the diagnosis of lupus is usually based on these findings:
evidence of a multi-system disease (more than one organ involved):
the presence of autoantibodies; the exclusion of other diseases and disorders which can mimic the features of lupus. Despite advances in medical education and technology it is still not uncommon for lupus to be incorrectly diagnosed or require a lengthy period of time to be diagnosed mainly because the symptoms vary so widely, come and go frequently, and because the disease mimics so many other disorders.
An important fact to remember concerning the treatment for lupus is that the diagnosis does not indicate the particular therapy to be used. In the absence of a cure, present-day treatment of lupus is still primarily tailored to symptomatic relief and not to the diagnosis.
=========================================================== This information is for"informational purposes" and is not meant to be used for medical diagnosis. Alwaysconsult your physician on matters such as this.
