Diagnostic
Tests For Ankylosing Spondylitis
Blood
tests show a moderate elevation of the ESR (sedimentation rate), the C-reactive
protein and serum immunoglobulin levels. Tests for RF or ANA titers are negative.
As stated before, the HLA-B27 test is often positive. However, this test is more
reliable when it is negative as in this case it then helps to exclude ankylosing
spondylitis. X-rays of the sacroiliac joints show very specific changes. These
changes characteristic for ankylosing spondylitis occur even in the earlier disease
process and are made more reliable by employing CT scans or MRI scans where more
detail can be seen. Typical X-rays of the lumbar spine occur later in the disease
and the "bamboo spine" happens only in a few advanced cases of ankylosing
spondylitis after about 10 years of the disease (Ref. 2, p. 446). Psoriatic
arthritis Psoriatic arthritis and the other spondyloarthropathies
have other signs that go along with the disease. For instance, with psoriatic
arthritis signs such as psoriasis plaques on the skin and pitting of nails that
are typical for psoriasis will often also be present at the same time. With the
bowel diseases of Crohns
disease and ulcerative
colitis the other bowel signs are present that have been described
under these links. Reiter's
syndrome This is a multifaceted disease where arthritis develops
after a genitourinary or gastrointestinal infection. The typical constellation
of symptoms is a symptom constellation of urethritis (inflammation of the urethra)
or cervicitis (inflammation of the cervical canal), conjunctivitis, mucous membrane
and skin lesions as well as arthritis. In the past when it was difficult to detect
Chlamydia strains, it was thought that Reiter's syndrome would be non infectious.
However, now the thinking on this has changed. What is known is that patients
who develop Reiter's syndrome are genetically found to have a high incidence of
70% to 95% of the HLA-B27 tissue antigen. This may make them more susceptible
to the strains of bacteria from sexually transmitted diseases or gastrointestinal
infections that are found in these patients with more sensitive culture methods.
Two major groups of patients have been identified among the Reiter's syndrome
patients. One group are mostly men in the 20 to 40 age group who develop the symptoms
following genital infections with Chlamydia trachomatis. Another group where men
and women are equally affected is the dysenteric form. This occurs after diarrhea
from bacterial enteric infections, likely because of a weakened immune system
in association with the HLA-B27 tissue antigen (Ref. 2). Common bacteria associated
with the dysenteric form are Shigella, Yersinia, Salmonella, Campylobacter and
Chlamydia. Reactive arthritis This is the
name used to describe that certain infectious diseases develop a concomitant arthritis,
but no bacteria can be found in the affected joint. It seems to be like a sympathetic
reaction, likely due to immune complexes that react with the affected joints.
There is an overlap with the dysenteric form of Reiter's syndrome. Other serious
infections that are associated with reactive arthritis are meningitis, pneumonia
with Chlamydia pneumoniae, diarrhea with enterotoxigenic strains of E. coli and
AIDS infection (due to HIV virus), just to mention a few examples. Appropriate
blood tests and cultures have to be taken in these cases.
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