How Common Variable Immunodeficiency Is Diagnosed

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Common variable immunodeficiency (CVID) is a condition in which the immune system has low levels of protective antibodies, leading to difficulty fighting off infections.

The diagnostic process involves a history of frequent infections, blood tests to assess immunoglobulin (antibody) levels, and certain lab tests to rule out other immune conditions.

Receiving a timely diagnosis of CVID is important because it can prevent complications and lead to better outcomes. Unfortunately, CVID can be difficult to diagnose.

There is not one single test that can diagnose CVID, and there is disagreement among experts on diagnostic criteria. Diagnosis is delayed at an average of four to nine years.

Close up of a doctor doing a medical exam while both he and the patient are wearing protective masks

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Self-Checks

While you cannot diagnose yourself with CVID, you may be able to recognize a pattern of symptoms before meeting with your physician.

Over 90% of people with CVID have recurrent viral or bacterial infections of the respiratory or gastrointestinal system. If you are sick often—for example, with colds that last for months or frequent diarrhea—you should discuss this with your physician.

CVID can also run in families, so you may want to talk with immediate family members and learn if anyone in your family has CVID or symptoms that could be a sign of CVID. Coming to your appointment with this information can be helpful in the diagnostic process.

Tracking Your Symptoms

Before seeing your physician, it can help to keep a journal or calendar history of your symptoms. This should include tracking how often you are sick, the duration of each illness, whether you went to urgent care or the hospital for any illness, and how your symptoms affect your life.

Physical Examination

If you or your physician suspects CVID, the first step is generally an in-office physical examination. This may include taking your temperature, listening to your lungs, checking your ears, nose, and throat, palpating your lymph nodes, and examining you for any active infection.

During this appointment, your physician will also ask some questions to gather important health and family history information. This information can help identify indicators of CVID or other conditions.

Questions you may be asked during a physical examination can include:

  • How often do you get sick?
  • What respiratory or gastrointestinal symptoms do you have when you are sick?
  • How long does each illness tend to last?
  • Is there any time when you feel “well” in between illnesses?
  • Have you ever had pneumonia?
  • Have you ever gone to urgent care or been admitted to the hospital for illness? How many times?
  • Have you ever had a poor response to vaccines?
  • Have you ever been diagnosed with an autoimmune condition?
  • Have you ever been diagnosed with liver disease or arthritis?
  • Have you ever been diagnosed with bronchiectasis or granulomas?
  • Does anyone else in your immediate family (parents or siblings) frequently get sick, and for long periods of time or with severe infections?
  • Does anyone else in your immediate family have a diagnosis of CVID or another immunodeficiency?

Laboratory Tests

After gathering your medical history to confirm a pattern of recurrent infections, the next step in diagnosing CVID is conducting blood tests.

Your primary care physician may run some of the screening blood tests themselves, or they may refer you on to an immunologist or hematologist for expert diagnosis.

Depending on your symptoms, they may also refer you to a gastroenterologist or pulmonologist for additional treatment.

Serum Immunoglobulin Test

The first test is typically an inexpensive blood test for serum immunoglobulins. Your physician will look for deficient results of IgG and either IgA or IgM, which are required for a diagnosis of CVID.

Deficient IgG is usually below 5 g/L, with normal ranges being 7 g/L to 16 g/L. If abnormal, IgA and IgM are often not detectable at all.

Routine Blood Test Screenings

Your physician will also order additional routine blood tests. These include:

These will detect abnormalities which could indicate CVID or another condition.

On your CBC, your physician will look specifically for cytopenias, or lower-than-normal blood counts of various types of blood cells. These have been linked to CVID.

Vaccine Antibody Tests

If indicated by your health history or confirmed by your initial screening tests, your physician may also administer blood tests to examine your response to vaccines.

These will test your body’s antibodies against diseases you may have been vaccinated for, including:

People with CVID often do not mount an adequate response to vaccines because of their low antibodies.

Differential Diagnosis

Differential diagnosis is the process by which healthcare providers rule out all other conditions that could explain your symptoms. By doing so, they ensure the most accurate diagnosis.

Although there are a few different diagnostic criteria for CVID, experts agree that it is essential to rule out all other possible causes of hypogammaglobulinemia (low IgG antibodies) before an official CVID diagnosis is given.

Some potential causes of low IgG, other than CVID, that should be evaluated include:

To rule out many of these conditions, your healthcare provider will require another blood sample. With this sample, they perform flow cytometric analysis, which is a tool that looks at certain blood cells one-by-one.

In the case of CVID, this will be set to analyze various lymphocytes, including total T, B, and natural killer cells.

If you have low B cells, your physician may order a bone marrow biopsy to help rule out lymphoma.

A Word From Verywell

Diagnosing CVID can be challenging for a number of reasons. You may have grown accustomed to getting frequent colds or other infections. In this way, CVID may “sneak up” on you.

While everyone gets sick at some point, it is not normal to feel sick all the time. If this is happening to you, make an appointment with your healthcare provider. An early diagnosis of CVID can lead to better health outcomes.

Many of the tests to diagnose CVID are non-invasive, routine blood tests. These, along with medical and family history, can lead you and your physician in the right direction.

Even if you don’t have CVID, you should not live with constant illness. Talking with your physician is the first step to getting better.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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