Jo-1 (Anti-Jo-1) Antibodies Test

The Jo-1 (Anti-Jo-1) antibody test is a targeted blood test used to investigate autoimmune muscle and lung disease. It is most often requested when a patient has unexplained muscle weakness, muscle pain, or breathing difficulties, and it is particularly valuable in the assessment of idiopathic inflammatory myopathies such as polymyositis and dermatomyositis. It also helps identify people with antisynthetase syndrome, a condition that can combine muscle inflammation, lung inflammation, arthritis, and skin changes.

The test measures antibodies directed against histidyl-tRNA synthetase, an enzyme also known as Jo-1. These antibodies belong to a group called myositis-specific autoantibodies. Their presence supports a diagnosis of an autoimmune myositis and can indicate a higher chance of interstitial lung disease, which is why early detection matters. The analysis is typically performed using an immunoassay technique that detects and quantifies the specific antibody in a simple blood sample.

What is included

• Jo-1 (Anti-Jo-1) antibodies: the single marker measured in this test, used to support the diagnosis of autoimmune myositis and antisynthetase syndrome.

Why it matters

Identifying Jo-1 antibodies can shorten the path to the right diagnosis when muscle weakness or breathlessness has no obvious cause. A positive result helps your doctor distinguish autoimmune myositis from other muscle and lung conditions, guides appropriate specialist referral, and supports monitoring for lung involvement that may need early treatment. Because results are interpreted alongside your symptoms, examination findings, and other tests, your doctor will discuss what the result means for you.

• Jo-1 (Anti-Jo-1) antibodies

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.