Doctors most often find TAK on an angiogram, a test that shows how well blood flows in arteries. A doctor often orders an angiogram when a patient has symptoms and abnormal results of the physical exam. These include loss of pulse or low blood pressure in an arm, or abnormal sounds (“bruits”) heard over large arteries with a stethoscope.
There are various types of angiograms, including standard ones that involve injection of dye directly into an artery while X-ray test are taken. Less invasive types of angiography use another imaging technique such as computed tomography, and this is CT angiography or CTA. When MRI—magnetic resonance imaging— is used, it is called magnetic resonance angiography or MRA.
Angiograms may show narrowing of one or more large arteries. It is important for the doctor to try to distinguish between narrowing due to vasculitis (inflammation of arteries) and narrowing due to atherosclerosis (“hardening” of the arteries). At times, this can be challenging. There are other causes of arterial narrowing as well, including fibromuscular dysplasia, another rare disease that mainly affects women.
Large arteries can also become inflamed in a few other diseases. Examples include other types of vasculitis: giant cell arteritis (a disease of older adults), relapsing polychondritis, Cogan’s syndrome and Behçet’s disease. Some infections can also cause inflammation in large arteries.
Blood tests for inflammation include measurements of the erythrocyte sedimentation rate (sometimes referred to as the “sed rate” or ESR) and C-reactive protein (often called CRP). Results of these tests are often, but not always, high in patients with TAK However, these tests are also abnormal in a large number of other inflammatory diseases. Patients with TAK may also have anemia due to chronic (long-term) inflammation. Anemia is also tested for a blood test. None of these blood tests can tell you for sure if you have TA, and these blood tests may be abnormal in many other diseases.
Patients with TAK may have no symptoms, and the disease is so rare that doctors may not easily recognize it. Thus, there is often a delay in detecting it, sometimes several years.