Yes, you’ll need to have blood tests done while you’re using Kesimpta. Before you start treatment, your doctor will order blood tests to check for infections, such as hepatitis B. They’ll also look at your immunoglobulin levels, which help show how well your immune system is working. (An immunoglobulin is a type of protein.)Your doctor will continue to monitor your immunoglobulin levels throughout your Kesimpta treatment. If your levels become too low, they may have you stop using the drug. Low immunoglobulin levels may cause you to develop infections easier than usual, which may be serious.Before you start using Kesimpta, talk with your doctor about blood tests that you need.