More than 90% of people with ankylosing spondylitis have a particular genetic marker called HLA-B27, which can be found on their white blood cells. This marker does not appear to be the only cause, however, as 80% of people with this genetic marker never develop an inflammatory disease.
There are no specific lab tests to identify ankylosing spondylitis. Certain blood tests can check for markers of inflammation, but many different health problems can cause inflammation. Blood can be tested for the HLA-B27 gene.
HLA-B27 contributes to approximately thirty percent of the heritability of ankylosing spondylitis. [2] The incidence of acute anterior uveitis in HLA-B27 positive patients has shown on meta-analysis to vary from 40 to 82.5%.
Acute phase reactants such as erythrocyte sedimentation rate (ESR) and C-reactive protein are useful markers of inflammation but are elevated in only 50–70% of AS patients.
Ankylosing spondylitis (AS) is a chronic, inflammatory disease of the axial spine. Chronic back pain and progressive spinal stiffness are the most common features of this disease. Involvement of the spine, sacroiliac joints, peripheral joints, digits, and entheses are characteristic.
Ochronosis frequently involves the spine and can mimic ankylosing spondylitis radiographically and clinically but spares the sacroiliac joint.
Early symptoms of ankylosing spondylitis might include back pain and stiffness in the lower back and hips, especially in the morning and after periods of inactivity. Neck pain and fatigue also are common. Over time, symptoms might worsen, improve or stop at irregular intervals.
Background. A hospitalized-based cohort study suggested that elevated C-reactive protein (CRP) levels are associated with radiographic sacroiliitis progression in ankylosing spondylitis (AS) patients.
Age of disease onset usually peaks in the second and third decades of life. Approximately 80% of patients with AS experience symptoms at ≤ 30 years of age, while only 5% will present with symptoms at ≥ 45 years of age.
Magnetic resonance imaging (MRI) uses energy from a powerful magnet to produce signals that create a series of cross-sectional images. These images or “slices” are analyzed by a computer to produce an image of the joint. MRI can help diagnose ankylosing spondylitis in the early stages of the disease.
Human leukocyte antigen B27 (HLA-B27) is strongly associated with ankylosing spondylitis (AS). However, the association between clinical findings and HLA-B27 vary in terms of geographic area.
A positive result means HLA-B27 was found in your blood. You may have a higher-than-average risk of certain autoimmune diseases, such as ankylosing spondylitis and reactive arthritis.
Evaluation of SIJ on pelvic X-rays according to the modified New York (mNY) criteria served for decades as the gold standard to ascertain a diagnosis of ankylosing spondylitis (AS) at a given time point.
X-rays and MRIs are the two most common imaging tests used to help diagnose ankylosing spondylitis, but they each have their limitations and challenges. European medical guidelines call for conventional X-rays of the sacroiliac joints as the first imaging method to help diagnose AS.
CRP level ranged from 0 to 195 mg/l at baseline. Mean CRP was 14.0 (18.6) (median 7.2) mg/l; an increase in CRP over 5, 10, 15 and 20 mg/l was observed in 522 (61%), 328 (39%), 249 (29%) and 181 (21%) patients, respectively.
HLA-B27 and Ankylosing Spondylitis
One gene, HLA-B27, is strongly associated with a big family of rheumatic diseases called spondyloarthropathies. It includes: Axial spondyloarthritis.
Ankylosing Spondylitis (AS) is a type of progressive arthritis that leads to chronic inflammation of the spine and sacroiliac joints. It can also affect other joints and organs in the body, such as the eyes, lungs, kidneys, shoulders, knees, hips, heart, and ankles.
This is yet another marker of inflammation and is raised in several inflammatory conditions. However, only 50–70% of patients with active disease will have an increased level of C reactive protein and a raised ESR.
This progression can take 10 years or more to happen. And not everyone with nr-axSpA will progress to AS. Another method of measuring progression is looking at inflammatory blood markers. Many people with active inflammatory axSpA have more signs of inflammation in their blood.
The three most commonly used inflammatory markers are called C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and plasma viscosity (PV).
This is the first phase of ankylosing spondylitis. It happens when nr-axSpA gradually gets worse and affects the sacroiliac joints and the bones of the spine. Your doctor will be able to see noticeable changes in these joints on an X-ray.
The most common symptom of ankylosing spondylitis is lower back and/or hip pain and stiffness. Over time, the symptoms may progress to other areas of the spine.