Ankylosing Spondylitis and Lab Testing

Ankylosing spondylitis is an arthritis type that targets the spine. The derivation of the term is from two Greek words that mean “bent spine” and “inflammation.” In other words, ankylosing spondylitis is generally a chronic condition that brings about pain inflammation of the joints within the spine’s vertebrae, and between the pelvis and spine. In advanced situations, the vertebrae might fuse, which further limits movement and leads to a hunched over posture. Ankylosing spondylitis can occasionally involve other joints or, more seldom, organs in the body, including the lungs and heart.  

Ankylosing spondylitis mostly affects men compared to women and is often diagnosed in early childhood or late adolescence. There seems to be a genetic component linked with ankylosing spondylitis, and this has to do with an antigen known as HLA-B27. Most people who have the HLA-B27 antigen don’t develop ankylosing spondylitis, but it’s still considered a huge risk factor. Although around 7% of the US population is positive for HLA-B27, 90-95% of those who have ankylosing spondylitis are also HLA-B27 positive. Only approximately 5-6% of people who are HLA-B27 positive will ever acquire ankylosing spondylitis. The study into other risk factors and possible triggers that result in ankylosing spondylitis is ongoing. 

You’ll find several reasons when it comes to the exact cause of the inflammation related to ankylosing spondylitis. One potential cause is that foreign DNA, like from a virus, might trigger the body’s immune system. However, the immune system over-reacts and begins attacking its cells, resulting in chronic inflammation. As of now, it is not known the exact reason for the inflammation found in ankylosing spondylitis. An example of the effects of chronic inflammation of the bone’s surrounding ligaments, specifically in the spine, is initiating new bone growth, and this can result in individual vertebrae fusing. Furthermore, the fusion of the vertebrae can result in the spine’s permanent reduced mobility, and stiffening of the rib cage. Once the ribcage becomes less flexible, the chest can’t expand fully as normal, and this lowers the capacity to breathe in air, which, in turn, causes difficulty in breathing.  

What Are the Signs and Symptoms? 

Typically, ankylosing spondylitis’s early symptoms include stiffness and pain in the lower back and hips, which might fluctuate over time and pass on to other body parts. In around 40% of people with ankylosing spondylitis, their eyes usually develop an inflammation known as uveitis, and this can cause blurred vision, sensitivity to light, and eye pain. Other complications can involve issues with the lungs and heart. 

Laboratory Tests 

At this time, there’s no single test that could diagnose ankylosing spondylitis. Typically, diagnosis is based on both signs and symptoms and imaging studies. Different laboratory tests might be performed along with medical history and physical examinations to help in supporting the diagnosis. Testing might include: 

  • Erythrocyte sedimentation rate (ESR). To check for the presence of inflammation. 
  • C-reactive protein (CRP). Another test for inflammation. 
  • HLA-B27 antigen test. To figure out if a person has this human leukocyte antigen joined to their cells, and this correlates with an increased risk of acquiring ankylosing spondylitis. Although the test doesn’t diagnose ankylosing spondylitis, the results, together with other results and assessment of physical signs and symptoms, assist in supporting or ruling out a diagnosis of ankylosing spondylitis. 
  • Complete blood count (CBC). This is to examine for anemia (which is a count of low red blood cells and a complicated chronic inflammation related to ankylosing spondylitis). It also checks for increased quantities of white blood cells, and thus an indication of inflammation.  

Early diagnosis enables interventions that might assist in preventing or delaying complications of the condition.