Juvenile arthritis (JA), also called juvenile idiopathic arthritis (JIA) because its cause is unknown, is a disorder in which the immune system mistakenly attacks healthy tissues, causing inflammation and damage.
There is no single test to diagnose juvenile arthritis, as its symptoms are not unique and because JA has multiple subtypes that can progress in very different ways. Diagnosis, for this reason, often requires undergoing tests to rule out other diseases, and to determine the type of JA present so that proper treatment can begin.
A diagnosis of JA is generally given to people younger than 16 years of age who have had arthritis symptoms for six weeks or longer, and who have no evidence of other diseases or conditions that might be the cause of reported symptoms.
A child is slightly more at risk of developing JA if a family member is known to have an autoimmune disorder, such as rheumatoid arthritis or multiple sclerosis. For this reason, the child’s and its family’s medical history is likely to be examined.
Personal medical history also helps to rule out a previous condition that could have caused damage and contributed to the symptoms being reported, such as a previous physical injury, Lyme disease, inflammatory bowel disease, lupus, dermatomyositis, and some forms of cancer.
A medical history is coupled with a physical examination and symptom assessment to confirm if those symptoms are in line with JA. This is often carried out by a specialist in arthritis called a rheumatologist. An assessment may include tracking the symptoms over time to see if they improve, stay the same, or worsen.
Blood tests are done to check for factors that are commonly associated with JA. These include testing for the presence of certain proteins that may produced as part of the unusual immune response in JA, such as C-reactive protein (CRP), anti-nuclear antibodies (ANA), rheumatoid factor (RF), and cyclic citrullinated peptide (CCP).
A specific type of blood test, that is called erythrocyte sedimentation rate (ESR) and measures the time it takes for red blood cells to settle at the bottom of a tube, can help to predict the presence and severity of inflammation. This is because inflammation can lead abnormal proteins to appear in the blood, causing red blood cells to clump together and settle more quickly.
A positive result generally indicates that the patient has JA. It is important to note, however, that a negative result in this or any of these blood tests does not rule out a possible juvenile arthritis diagnosis.
Other laboratory tests
Samples other than blood may be taken to exclude other conditions. For example, a sample may be taken from the bone marrow to rule out some rare conditions. Fluid may be removed from a joint, through a process called aspiration, to test for infection at a symptomatic site. Genetic testing for certain markers that are thought to be associated with some types of JA, such as HLA-B27, may also be requested.
Imaging scans are initially done to exclude other conditions, and can also determine joint damage caused by JA if the symptoms have progressed. Scans can include X-rays, magnetic resonance imaging (MRI), CT scans, or an ultrasound.
Note: Juvenile Arthritis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.