Your first step is to go to your GP
You should be ready to explain:
- What symptoms you are experiencing
- How long these have been going on (weeks, months, years)
- How the symptoms started (suddenly or came on slowly over time)
- What impact your symptoms are having on your daily life / what are they stopping you from doing (be sure to highlight any issues around sleeping and work)
If another member of your family has AS please make sure that you highlight this to your GP. If you have ever suffered with any of the following problems please also highlight this.
- Inflammation in your eyes (uveitis/iritis)
- Inflammatory bowel disease (ulcerative colitis or Crohn's disease)
If your GP suspects AS you should be referred to a rheumatologist at a hospital
A rheumatologist is a doctor specialising in conditions such as AS. They will confirm if your condition is AS, decide the initial treatment and oversee the long term management of your condition.
Tests which might be used to help diagnosis your AS might include:
A physical examination by a nurse, physiotherapist or rheumatologist to assess your flexibility and joint tenderness.
A blood test to look at inflammatory markers. If you have inflammation in a part of your body then extra protein can be released from the site of inflammation and circulates in the bloodstream. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and plasma viscosity (PV) blood tests are commonly used to detect this increase in protein, and so are markers of inflammation.
We know that in around 50% of cases of AS, inflammatory markers will be within the normal range. Therefore just because your inflammatory markers are normal it does not mean you do not have a form of inflammatory arthritis.
A blood test which can identify if you have the HLA-B27 gene. We know there is a strong association between AS and the HLA -B27 gene. In white western Europeans about 8% carry this gene.
Although HLA B27 is present in over 95% of people with AS, only about 1 in 15 people who are HLA B27 positive go on to develop AS. Just carrying the HLA-B27 gene does not necessarily mean you have AS but if you do test positive it is a clue that your symptoms might point towards AS.
Do remember that 5% of people with AS are HLA-B27 negative so if you have lots of the symptoms of inflammatory arthritis but are HLA-B27 negative it's important to have further investigations.
X-rays will show if there has been any changes to your bones and joints. Your rheumatologist will be looking for signs of extra bone growth or fusion. It can take many years for AS to cause changes to your bones so it is likely that nothing will show on x-ray in early AS.
Magnetic resonance imaging (MRI) which will show if there is any inflammation around your joints.
A particular MRI sequence needs to be used to diagnose AS. It is called a STIR sequence (Short TI Inversion Recovery).
If your rheumatologist arranges your MRI they will know what to request. If your GP requests your MRI, check that they have requested that you be investigated for inflammatory arthritis or AS rather than simply requesting you be checked for back pain.