I'm not sure I'll be able fully answer your question for you, but I
think I can give you the main points. Here goes...
1. Lab test results should only be interpreted by somebody with the
training to do so, i.e. a physician. The test mentioned above suggest
a workup for a connective tissue disease (lupus, rheumatoid arthritis,
sjogren syndrome, etc) and these diseases are generally diagnosed
clinically. The lab testing is meant to be interpreted within the
context of the patient's clinical picture.
2. All labs are different. Granted, there are some generally accepted
'normal ranges' but that normal range depends on how the test is
performed in the lab. Therefore, the only reliable way to know what
the normal values are for your test is to contact the lab that did it
and ask for their range of normal values. Your physician may already
have this data, and it is often printed on the lab paperwork next to
your data. If necessary, call the lab and ask to speak to somebody
who works with the antibody/immunology testing.
3. The 1:40 number refers to a dilution of a sample. The 'one'
represents the patient's sample. The second number (forty in this
case) refers to the relative amount of neutral fluid the sample was
mixed with. So, for the ANA test, the lab took one part patient
sample and 40 parts diluting fluid and mixed them together. The fluid
(which is now 2.5% original sample, 97.5% 'other') is then tested, in
this case for anti-nuclear antibodies. In most labs, the normal is
for the test to be negative at a 1:40 dilution. If it's positive,
then the dilute it further (1:80, 1:160, etc) until the test becomes
negative for ANA's. So the larger the second number, the more they
had to dilute it to make the test negative, and therefore the larger
the amount of ANA that was present in the initial sample.
4. Each of the other tests has its own (lengthy) answer as to how it
is performed. The tests all represent autoantibodies (antibodies made
against our own body), and the pattern of which tests are positive and
which are negative, in the clinical context of an individual patient,
may suggest a particular disease or syndrome.
Most of the resources I used are pretty technical. You're definitely
encouraged to take a look at them, though. Try this article
http://jcp.bmjjournals.com/cgi/content/full/53/6/424
which explains the utility of these (and other) immunology test in the
context of lupus. However, some of the information (like the fact
that 1 in 3 healthy people have a positive ANA at 1:40 dilution, and
1/20 are still positive at 1:160) is applicable to anyone having these
test done.
Also, if you have a local health sciences library (like at a medical
school) or a large university library, you may want to check out a
textbook on laboratory medicine (I looked at Henry: Clinical Diagnosis
and Management by Laboratory Methods, 20th ed, but there are many
others).
Here's a more layman-friendly article on ANA:
http://patients.uptodate.com/topic.asp?file=arth_rhe/8855#11
-This site also has similar information on other connective
tissue/rheumatic diseases that you may be interested in.
I hope this gets you started. You're right, this is a confusing area
of medicine, and that's why Rheumatologists tend to be pretty smart
people. The best advise you can get on these tests is from your
physician. |
