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Updated on March 18, 2025
Primary immunodeficiency (PI) refers to a group of genetic defects and disorders that impact how the immune system functions. These conditions are also known as primary immunodeficiency disorders (PIDDs). In some cases, PI are called inborn errors of immunity (IEIs), though not all PI are inborn or inherited—many forms occur sporadically or are not fully understood. There are over 450 recognized types of PI, and new types of PI are being identified regularly due to advances in genetic testing.
When a person has PI, some part of the immune system does not function correctly. As a result, people with PI will be more susceptible to infections (including rare, severe, recurring, and difficult-to-treat infections) as well as other diseases, such as certain cancers.
Treatment for PI
Treatment for PI will depend somewhat on the specific PI that a person has, and the first step to successful treatment will be getting an accurate diagnosis. Treatment can include:
- Antibiotic, antiviral, and antifungal medications, which are used to treat or prevent infections.
- Immunoglobulin replacement therapy, which provides the body with infusions of antibodies that help the immune system function. These can be delivered with an intravenous infusion (IVIg) or a subcutaneous infusion (SCIg).
- Hematopoietic stem cell transplantation (HSCT), also known as a bone marrow transplant, a procedure that can potentially cure certain cases of PI. This procedure comes with a risk of serious side effects and is only used in certain cases.
- Gene therapy, which is a new and emerging therapy. Some gene therapies are available for certain types of PI, and others may be available in clinical trials.
In addition to medical therapies, treatment should also include strategies to prevent infections, such as staying up to date on vaccines, washing hands frequently, avoiding people who are sick, and following guidelines for safe food handling.
Questions when starting a new therapy
A person with PI may change therapies during treatment. For example, immunoglobulin infusions are a mainstay of treatment for many forms of PI. In some cases, a person may be given intravenous immunoglobulin (IVIg) during the initial phase of treatment (called a loading dose). Intravenous immunoglobulin is administered with a needle inserted into a vein, and this must be done by a healthcare provider.
After the loading phase, a person may switch to subcutaneous immunoglobulin (SCIg) infusions for long-term maintenance therapy. SCIg is administered into a layer of tissue immediately under the skin using a needle. This can often be done at home, and either self-administered or administered with the help of a caregiver.
It's important to know about all therapies and medications that you are taking. If you are discussing a new treatment option or a change in treatment with your healthcare provider, here are some questions to ask:
- What is the name of the therapy? What dosage is being recommended?
- How does this therapy work? What is the goal of using this therapy?
- How is the therapy administered and how often?
- How long will I be taking this therapy?
- What are the potential benefits of this therapy?
- What are the potential risks and side effects? Is there a risk of serious side effects?
- What will this therapy cost? What can I do if I have concerns about the cost of treatment?
- Are there things I should avoid doing while using this therapy? For example, eating certain foods or engaging in certain activities.
- Can this therapy interact with other medications? Bring a list of all medications you are taking, including medications for other conditions, over-the-counter medications, and supplements.
Remember, your healthcare provider is your best source of information. If you have a question, have a concern, or need an explanation, bring this up during your appointment.
