Lab Tests for Rheumatoid Arthritis: What Do My Labs Mean?

Lab Tests for Rheumatoid Arthritis: What Do My Labs Mean?

Monitoring with blood tests (commonly referred to as “lab work”) is recommended to make sure the treatment that you and your doctor select is both safe and effective. Your doctor may recommend frequent lab work while taking medications for RA, especially when you first start a new medication.

This information is part of CreakyJoints’ comprehensive guide for patients living with rheumatoid arthritis. Learn more or download Raising the Voice of Patients: A Patient’s Guide to Living with Rheumatoid Arthritis.

What do my labs mean?

Your lab tests are used to monitor your health during your treatment plan. The most common tests will monitor your liver, your kidney function, and your blood counts.

Liver toxicity is measured with transaminase (AST/ALT) levels. A transaminase is a type of liver enzyme. Your liver can make and release transaminases when it’s injured or weakened in some way. Higher transaminase levels may indicate liver damage.

Creatinine and BUN (blood urea nitrogen) levels are used to assess your kidney function. Even if the RA medication you are taking does not impact the kidney, it is important to keep track of its function because a change in kidney function can affect the level of your RA medicine in your blood. Creatinine is a waste product that your kidneys filter after muscle breakdown and remove through your urine. Your kidneys also remove and flush out urea, a waste product of protein breakdown. If your creatinine or BUN levels are high, it means your kidneys are not able to filter these waste products effectively. They could build up and cause problems.

Complete Blood Count (CBC) testing is done to ensure that you have the right amount of red blood cells, white blood cells, and platelets in your blood. Many medications used to treat RA can affect the bone marrow that makes these blood cells. Active disease may also impact the levels of these cells. It’s important to keep these different types of blood cells in balance for good overall health. If your CBC is abnormal, your doctor may change the dose or type of drug you are taking.

Sometimes it might be necessary to measure levels of a medication in your blood to check for toxicity or to make sure you are taking enough of the medication. This test will ensure the drug level in your blood is both effective and safe.

Vectra DA is another type of blood test that can help determine the level of activity of your RA.  It is a combination of 12 measurements of different markers in your blood that can point to low, moderate, or high disease activity. High disease activity levels may predict more joint damage in the future. Vectra DA is a new blood test that is not available in all health systems or reimbursement programs.

There are various imaging techniques that can monitor the effect of RA on your bones and joints. The most common and widely used technique is the X-ray. More recently, MRI (magnetic resonance imaging) and US (ultrasound) have been used as they can detect smaller changes in the joints earlier than X-ray.