American Board of Internal Medicine (ABIM) Certification Practice Exam

What additional screening is recommended for MS patients treated with natalizumab to mitigate risks?

1. MRI of the brain

2. JC virus antibody screening

3. Thyroid function tests

4. Vitamin D levels

The correct answer is: JC virus antibody screening

Patients with multiple sclerosis (MS) who are treated with natalizumab should undergo JC virus antibody screening to mitigate risks associated with potential reactivation of the John Cunningham virus (JCV). Natalizumab is an immunomodulatory therapy that can increase the risk of progressive multifocal leukoencephalopathy (PML), a serious viral infection of the brain caused by the JCV. Identifying the presence of JC virus antibodies in the patient helps assess the risk of developing PML while on natalizumab treatment. If a patient is antibody-positive, it indicates past exposure to the virus, which has implications for monitoring and managing their treatment. Regular screening allows clinicians to make informed decisions regarding the continuation of natalizumab therapy, balancing the benefits against the risk of developing PML. Other screening options, while important in the overall management of patients with multiple sclerosis, do not directly address the specific risk associated with natalizumab treatment. For instance, performing an MRI of the brain helps assess disease activity but does not provide information regarding JC virus status. Thyroid function tests and vitamin D levels are relevant in general MS management but do not mitigate the specific risks related to natalizumab and PML. Thus, JC virus antibody screening is the most effective