Ankylosing Spondylitis, Orthopedic Perspective (cont.)
Exams and Tests to Diagnose AS
A doctor begins with a complete medical history and physical exam. The medical history of the person and his or her family members provides possible clues to help determine a diagnosis of AS. It is common for patients with AS to have other family members with AS. Also, symptoms are typically worse in the morning and progressively improve throughout the day and with exercise.
- The physical exam measures range of motion in the hips and spine. Specific areas of pain or tenderness are examined. A thorough exam should identify any of the associated disorders, including involvement of the eyes, heart, and lungs.
- A blood test can determine if a person has the protein HLA-B27. A person with this protein has an increased risk of developing ankylosing spondylitis. If it is positive, it may be helpful in diagnosing the condition. However, this blood test may be negative in some people with AS. This test is not necessary to treat the condition and is not commonly ordered by a doctor. Other blood tests may be ordered by a doctor to help rule out other possible causes of the person's symptoms.
- Blood tests are not very helpful in diagnosing ankylosing spondylitis. A blood test can determine if a person has the protein HLA-B27. A person with this protein has an increased risk of developing ankylosing spondylitis. However, this blood test is not necessary to diagnose or treat the condition and is not commonly ordered by a doctor. Other blood tests may be ordered by a doctor to make sure the patient does not have other disorders that could be causing his or her symptoms.
- Imaging studies (X-ray films) of the pelvis and the spine are commonly obtained to look at the sacroiliac (SI) joints and hips. The sacroiliac joints must be affected for proper diagnosis of ankylosing spondylitis. X-ray findings in the spine include squaring of the vertebral bodies and formation of bridging bone connecting the vertebrae.
- X-ray films of other joints may show loss of the normal space between the bones or abnormal curves of the bones (deformities).
- In people with weakness, decreased feeling in the arms and legs or abnormal reflexes (neurologic findings), an MRI of the spine may be ordered to look at the nerves and spinal cord.
Medically Reviewed by a Doctor on 11/20/2017
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