Health condition
Low immunoglobulins
Low immunoglobulin levels on a blood test range from clinically silent dips to significant antibody deficiency; the work-up asks three questions - how low, why, and is the immune system functionally compromised - before deciding between monitoring and replacement.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
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Common secondary causes come first: medications (rituximab, long-term steroids, some anticonvulsants), protein loss through kidneys or gut, haematological conditions (CLL, myeloma, lymphoma) - secondary hypogammaglobulinaemia outnumbers primary in adults
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Severity and pattern matter: isolated borderline IgM dips differ from panhypogammaglobulinaemia; IgG below about 4-5 g/L with infections signals likely clinical significance
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Function decides treatment: vaccine response testing shows whether remaining antibody production works - poor responses plus infections build the case for immunoglobulin replacement
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Specialist: a consultant immunologist; established significant deficiency (such as CVID) is managed with lifelong replacement therapy, infection vigilance and monitoring of the associated complications
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
A low immunoglobulin result arrives by two main roads: as an incidental finding on tests run for fatigue, protein studies or liver panels in someone with no infection history - where mild isolated reductions are common and frequently meaningless - or as the sought answer in someone whose recurrent sinopulmonary infections finally prompted the right test; the assessment differs accordingly, but both begin with the secondary-cause sweep that dominates adult practice: the medication list (rituximab's B-cell depletion, years of corticosteroids, carbamazepine and phenytoin among anticonvulsants), protein leakage through nephrotic kidneys or protein-losing gut, and the lymphoproliferative diseases - chronic lymphocytic leukaemia, myeloma, lymphoma - for which hypogammaglobulinaemia is sometimes the first laboratory whisper, making blood film and electrophoresis obligatory companions to the immunoglobulin result.
Diagnosis and treatment routes
With secondary causes addressed or excluded, the primary question becomes functional: repeat and trend the levels, measure specific antibodies against pneumococcus, tetanus and haemophilus, vaccinate and remeasure - a system that mounts robust responses and belongs to an infection-free person can usually be monitored, while impaired responses in an infection-marked history move towards a primary antibody deficiency diagnosis such as common variable immunodeficiency, with its structured care: immunoglobulin replacement (intravenous or subcutaneous at home) restoring protective levels and demonstrably reducing infections and organ damage, alongside surveillance for the condition's non-infectious dimensions. The middle ground - modest reductions, ambiguous function, few infections - is managed with annual review, a low threshold for treating bacterial infections promptly and properly, vaccination optimisation, and patient education on the symptoms that would accelerate the timetable; deterioration declares itself in trends, which is precisely what scheduled monitoring exists to catch. In many parts of the UK, routine NHS referrals for this kind of problem currently take 20-45+ weeks, whereas an initial appointment with a private consultant is typically available within around two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant immunologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Low immunoglobulins.
Quick, plain-English answers to what people ask us most.
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What does it mean to have low immunoglobulins?
Low immunoglobulins mean reduced levels of the antibody proteins your immune system uses to fight infections, which can increase susceptibility to certain infections, particularly bacterial ones affecting the respiratory tract and sinuses. This can be caused by an inherited immune deficiency or develop due to another underlying condition.
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What causes low immunoglobulins?
Causes include primary immunodeficiency conditions present from birth, certain medications (including some used for autoimmune conditions or after transplant), blood cancers such as certain lymphomas or myeloma, and conditions causing protein loss, such as significant kidney or gut disease. Identifying the underlying cause guides appropriate management.
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What are the symptoms of low immunoglobulins?
The main symptom is an increased frequency or severity of infections, particularly recurrent chest infections, sinusitis, or ear infections, sometimes with infections that are harder to clear or unusual in type. Some people have no obvious symptoms despite low levels found on blood testing.
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Is having low immunoglobulins dangerous?
It can increase the risk of serious or recurrent infections if not properly managed, so identifying and treating the underlying cause, along with proactive infection prevention strategies, is important. With appropriate management, most people with low immunoglobulins can significantly reduce their infection risk.
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Are low immunoglobulins hereditary?
Some causes, particularly primary immunodeficiency conditions, are genetic and can run in families, while others are acquired due to medication, illness or another underlying condition rather than being inherited. Genetic testing can help clarify this if a primary immunodeficiency is suspected.
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Can low immunoglobulins be treated?
Yes, treatment depends on the cause and severity, ranging from treating any underlying condition, to prophylactic antibiotics for recurrent infections, or immunoglobulin replacement therapy for more significant deficiency. Your immunology specialist will tailor treatment to your specific level of deficiency and infection pattern.
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How are low immunoglobulins treated?
Treatment options include regular immunoglobulin replacement therapy (given by infusion) for significant deficiency, prophylactic antibiotics to reduce infection frequency, and prompt treatment of any infections that do occur. Addressing any identified underlying cause is also an important part of management.
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How are low immunoglobulins diagnosed?
Diagnosis involves specific blood tests measuring different classes of immunoglobulins, alongside a detailed history of infection pattern and frequency. Further tests may be needed to identify an underlying cause, particularly if a primary immunodeficiency is suspected.
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Primary vs secondary immunoglobulin deficiency — what's the difference?
Primary immunoglobulin deficiency is an inherited condition present from birth affecting the immune system's ability to produce antibodies, while secondary deficiency develops later due to another condition, medication or illness affecting antibody levels. This distinction guides investigation and, in the case of secondary causes, whether addressing the underlying condition might improve levels.
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When should I see a specialist about low immunoglobulins, and how quickly can I be seen privately?
Recurrent or unusual infections, or abnormal blood test results, should prompt immunology referral. Private immunology consultations can typically be arranged within about two weeks, considerably faster than standard NHS waiting times.