Causes of Rheumatoid Arthritis

The medical community hasn't pinpointed the exact cause of rheumatoid arthritis (RA), although they have some leads.

RA and the Immune System
RA is an immune disorder termed seropositive. This means in many patients with RA, higher levels of a special factor—the rheumatoid factor (M class)—can be identified in their blood (serum). The increased presence of that rheumatoid factor does not guarantee the presence of RA, though. In fact, not everyone who tests positive for the rheumatoid factor develops the disease.

Here's how the rheumatoid factor may lead to the development of rheumatoid arthritis:
We all should have the antibody known as the rheumatoid factor; it's a normal part of the body's immune system. If you have the right amount of rheumatoid factor, then your immune system functions as it should. If you have a higher level of the rheumatoid factor in your blood, though—if you're seropositive—then it's possible that your immune system may start malfunctioning. Increased levels of rheumatoid factor may cause your immune system (white blood cells are a part of that) to attack healthy tissues, leading to RA.

You must remember this: the rheumatoid factor level is not a fool-proof test for RA. It's possible to have increased levels of rheumatoid factor and not have RA; it's also possible to have a normal rheumatoid factor level and still have RA. However, there is a higher likelihood of RA if your rheumatoid factor level is off.

RA and Heredity
Researchers indicate the disease cannot be inherited. However, the susceptibility toward development could be, although this has not been proven.

The genetic marker HLA-DR4 is possibly involved in rheumatoid arthritis. Researchers have found that a majority of people with RA have this genetic marker—but not everyone does. Like the rheumatoid factor in blood, the presence of the marker does not necessarily mean that you'll have RA.

This connection to genetics and heredity indicates that genetic make-up is a part of what causes RA, but it's not the only factor.

RA and Women
It seems that women are more likely to develop RA than men, although again, researchers aren't entirely sure why that is. They have noticed a possible connection between women's hormones and RA.

For example, pregnancy can actually relieve some symptoms of RA, so it seems that the hormones present then alter the effects of rheumatoid arthritis. Some researchers think that some molecules in the immune system (specifically interleukin 12 [IL-12] and tumor necrosis factor-alpha [TNF-α]) are affected by pregnancy-related hormone changes.

Breastfeeding and contraceptives may also change the immune system and have something to do with rheumatoid arthritis.

RA and Infection / Bacteria / Viruses
Some researchers believe that something must happen to "set off" the development of rheumatoid arthritis. In other words, say that someone has the HLA-DR4 genetic marker. It's possible that something occurs to "turn on" the marker's effect on the immune system. It's thought that an infection—from a virus or from bacteria—could be that trigger.

Like other potential causes of RA, researchers aren't entirely certain which infection has the ability to "set off" RA.

Regardless of What Causes RA…
Even if researchers haven't figured out the precise cause of rheumatoid arthritis, the process of RA is fairly well-laid out.

The body's joints are lined in a membrane called the synovium. In rheumatoid arthritis, the white blood cells, whose normal duty is to provide immunity, turn against the synovial membrane, causing inflammation.

In turn, inflammation triggers the release of chemicals, causing the synovial membrane to thicken. Destructive enzymes in the synovial fluid create a granulated membrane (pannus) that covers the normal joint surface.

Over time, these chemicals and enzymes can destroy joint cartilage, bone, tendons, and ligaments. As these structures are compromised, the joint loses it shape, alignment, and function.