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Family Medicine
Family Medicine, Doctor (MD)
Category: Health
Satisfied Customers: 710
Experience:  Board certified Family Medicine
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What if ANA positive, Sm/RNP positive, Sm negative and RNP

Customer Question

What if ANA positive, Sm/RNP positive, Sm negative and RNP negative?
Submitted: 8 years ago.
Category: Health
Expert:  Family Medicine replied 8 years ago.

Hello rosie

ANA (Anti Nuclear Antibodies) becomes + in autoimmune diseases like systemic lupus erythematosis or SLE,polymyositis and others.

Anti- sm/RNP positive means autoimmune disease including mixed connective tissue disorder, systemic sclerosis, scleroderma primary sjorgen,s syndrome etc.

It is positive in 90% of cases of mixed connective tissue disorders, 40% positive in SLE,and 30% cases of systemic sclerosis.

Now, if anti smith or Anti-sm antibodies are negative, it is almost certain that ANA positive is not because of SLE but because of other auto immune diseases.

Anti RNP is highly associated with mixed connective tissue disease and its absence almost excludes that option as well.

So it seems more like a case of either progressive systemic sclerosis, sjorgens syndrome, or scleroderma.

But you can not diagnose just on the basis of labortary tests. Clinical presentation and history is more important in order to know the underlying auto immune disorder.

Best wishes

Family Medicine and 4 other Health Specialists are ready to help you
Expert:  Family Medicine replied 8 years ago.

Rose are you clear about it ?

Please let me know if need more help.

Customer: replied 8 years ago.

Both SS-A and SS-B were negative so can I rule out Sjogren's? Have you ever hear of cases of autoimmune diseases being induced by cheomtherapy or radiation?


Expert:  Family Medicine replied 8 years ago.


Ionizing radiations can cause autoimmune disease by altering the immune system.

It depends on radiation dosage and duration of exposure.

Chemotherapy is used to treat autoimmune diseases as these works by altering immune system. Chemotherapy can cause induction or of autoimmune disease as well.

Fro sjorgen syndrome, Anti SS-A( called Ro) and Anti SS-B( called La) have high specificity but not 100 % sensitivity. These are positive in most of the cases of sjorgens but if ANA is positive, then negative SS-A and SS-B can not rule out sjorgen,s syndrome 100%.

As I mentioned earlier, clinical presentation of auto immune diseases is different but lab results may be overlapping. SO you always go with symptoms and clinical presentation and get support from lab results..