IgM blood test: what high and low immunoglobulin M levels mean
Immunoglobulin M (IgM) · Quantitative immunoglobulins (IgG, IgA, IgM); sometimes with serum protein electrophoresis · reported in mg/dL (outside the US, g/L; 1 g/L = 100 mg/dL)
Immunoglobulin M (IgM) is the first antibody the immune system produces when it meets a new infection, appearing within about a week and fading over the following weeks to months as IgG takes over. It is a large pentamer, five antibody units joined in a ring, which makes it very good at clumping bacteria and activating complement but too big to leave the bloodstream or cross the placenta. A total IgM blood test measures the whole circulating pool, regardless of target; for adults the normal range is roughly 40 to 230 mg/dL (0.4 to 2.3 g/L), a little higher in women than men, with labs differing in their exact limits.
A high total IgM is usually a short-lived response to an acute infection (viral hepatitis, mononucleosis, cytomegalovirus and others), and it is also raised in some chronic conditions, notably primary biliary cholangitis, rheumatoid arthritis and some chronic infections. The important exception is a monoclonal IgM made by a single clone of abnormal cells, which defines IgM MGUS and Waldenström macroglobulinemia; because IgM is so large, a high monoclonal level (usually above about 4,000 mg/dL) can thicken the blood enough to cause headaches, blurred vision and bleeding, the hyperviscosity syndrome. In newborns, where IgM is normally almost absent, a raised level suggests an infection acquired before birth.
A low IgM is common and often of little consequence on its own, but it accompanies a low IgG in most of the serious antibody deficiencies and is one of the first immunoglobulins to fall after rituximab or in multiple myeloma. The test is read with IgG and IgA, and when a high IgM is found, with serum protein electrophoresis to tell a polyclonal rise from a monoclonal one.
IgM at a glance
- What it is: the first-response antibody, made within about a week of a new infection; a large five-unit molecule confined to the blood, about 5 to 10 percent of circulating antibody.
- Normal (adults): about 40–230 mg/dL (0.4–2.3 g/L); women run slightly higher. Newborns under about 20 mg/dL; adult levels by about age 10. Labs differ.
- High IgM: acute infection (polyclonal), chronic liver disease (especially primary biliary cholangitis), autoimmune disease, or a monoclonal IgM from MGUS or Waldenström macroglobulinemia; hyperviscosity symptoms usually appear above about 4,000 mg/dL.
- Low IgM: medications (rituximab, steroids, immunosuppressants), multiple myeloma or CLL, protein loss, CVID or selective IgM deficiency; low IgM alone is usually harmless, low with IgG is not.
- IgM vs IgG on an infection test: IgM positive means recent or current infection; IgG positive with IgM negative means past infection or vaccination.
- Next step: for high IgM, protein electrophoresis with immunofixation and tests for the suspected infection or liver disease; for low IgM, IgG and IgA, a medication review and, if infections are frequent, vaccine antibody titers.
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What IgM measures
IgM is the heaviest antibody, a ring of five Y-shaped units joined by a J chain with a combined mass of about 900 kilodaltons, which is why it was historically called 'macroglobulin'. The ten binding sites give it enormous avidity for repetitive targets such as bacterial cell walls, and a single bound IgM molecule can trigger the complement cascade, making it the most efficient antibody for clearing blood-borne bacteria. It is also the antibody of the natural, pre-immune repertoire (including the ABO blood-group antibodies) and the form every B cell makes first before switching to IgG, IgA or IgE.
The lab measures total IgM by nephelometry or turbidimetry and reports it in mg/dL in the US (g/L elsewhere; 1 g/L = 100 mg/dL). This is different from IgM serology for a specific infection (hepatitis A IgM, EBV VCA IgM, toxoplasma IgM), which detects antibody against one organism and reports positive or negative or an index value; a positive specific IgM rarely raises the total IgM by much, while a high total IgM says nothing about which organism is involved.
IgM has a half-life of about 5 days, so it changes faster than IgG, rising within one to two weeks of an acute infection and usually returning to baseline within two to three months. Levels are very low at birth because maternal IgM cannot cross the placenta, so a cord-blood IgM above about 20 mg/dL points to an infection acquired in the womb. No fasting is needed; recent vaccination or infection, pregnancy (slightly lower) and a recent IVIG infusion (which contains almost no IgM but may transiently shift results) are worth noting.
Normal range for IgM
Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.
| Group | Typical range (mg/dL (outside the US, g/L; 1 g/L = 100 mg/dL)) | Notes |
|---|---|---|
| Adults | About 40–230 mg/dL (0.4–2.3 g/L) | Labs differ; some quote 20–200 or 50–300 mg/dL. Women average about 20 percent higher than men. |
| Newborn (cord blood) | Under about 20 mg/dL | Maternal IgM does not cross the placenta; a higher value suggests infection acquired before birth (TORCH infections, syphilis). |
| Infants and children | About 20–100 mg/dL in the first year, rising to adult levels by about age 10 | Pediatric labs use age-specific ranges. |
| Low IgM | Below about 40 mg/dL | Common and often harmless on its own; evaluated when IgG is also low, infections are frequent or a blood cancer is possible. |
| Selective IgM deficiency | Below about 20 mg/dL with normal IgG and IgA | Rare; some definitions use the lab's lower limit. Some people have recurrent infections, most do not. |
| Polyclonal high IgM | 230–500 mg/dL, occasionally higher | Acute infection, liver disease or autoimmune disease; electrophoresis shows a broad band. |
| Monoclonal IgM | IgM MGUS: M-protein under 3,000 mg/dL with under 10 percent lymphoplasmacytic cells in the marrow; Waldenström: any level with marrow involvement | Defined by electrophoresis, immunofixation and marrow biopsy, not by the total IgM. |
| Hyperviscosity threshold | Usually above about 4,000 mg/dL (40 g/L), with serum viscosity above 4 centipoise | Symptoms can occur at lower levels in some people; the level at which symptoms appeared before is the best guide for that person. |
High IgM
A high total IgM means either that many B cells are making their first-response antibody (a polyclonal rise) or that a single abnormal clone is overproducing one IgM (monoclonal). Polyclonal rises are the common ones: acute viral infections such as hepatitis A, mononucleosis, cytomegalovirus and dengue, early bacterial infections, and malaria push IgM up for a few weeks. Among chronic conditions, primary biliary cholangitis is the classic cause, with IgM raised in about 80 percent of patients and used as a supporting feature of the diagnosis; rheumatoid arthritis, Sjögren's syndrome, lupus and some chronic infections (hepatitis C, HIV, chronic parasitic infection) also raise it. Rarely, a raised IgM with low IgG and IgA in a child or young adult indicates one of the hyper-IgM syndromes, in which B cells cannot switch classes.
A monoclonal IgM is found in about 15 to 20 percent of all monoclonal gammopathies. Most are IgM MGUS, which progresses to Waldenström macroglobulinemia, lymphoma or related disease at about 1.5 percent per year, somewhat faster than IgG MGUS. Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma of the bone marrow that secretes IgM; it is diagnosed when there is any IgM M-protein together with 10 percent or more lymphoplasmacytic cells in the marrow, most carrying the MYD88 L265P mutation. It is a slow-growing cancer, often found incidentally and watched for years before treatment is needed.
The size of the IgM matters more than for other immunoglobulins because of hyperviscosity. The pentameric molecule is largely confined to the blood and thickens it in proportion to concentration, and above about 4,000 mg/dL (serum viscosity over 4 centipoise) a significant proportion of people develop headache, blurred vision, nosebleeds, bleeding gums, dizziness or confusion, with engorged retinal veins on eye examination. This is an emergency treated with plasma exchange. Monoclonal IgM also causes problems through its antibody activity: cold agglutinin hemolytic anemia, cryoglobulinemia and anti-myelin neuropathy.
Common causes
Acute viral and other infections
Hepatitis A and acute hepatitis B, Epstein-Barr virus (mononucleosis), cytomegalovirus, dengue, rubella, toxoplasmosis and malaria raise total IgM for a few weeks; it is the expected response and settles as IgG takes over.
Primary biliary cholangitis
The autoimmune bile duct disease classically raises IgM, often to 2 to 3 times normal, alongside raised alkaline phosphatase, GGT and antimitochondrial antibodies; the level falls with ursodeoxycholic acid treatment.
Waldenström macroglobulinemia
A lymphoplasmacytic lymphoma secreting monoclonal IgM; presents with fatigue, anemia, enlarged lymph nodes or spleen, neuropathy or hyperviscosity. About 1,500 new US cases a year, mostly in people over 65.
IgM monoclonal gammopathy of undetermined significance
An IgM M-protein under 3,000 mg/dL with less than 10 percent marrow involvement and no symptoms; progresses to Waldenström or lymphoma at about 1.5 percent per year, so it is monitored with periodic electrophoresis.
Autoimmune and connective tissue disease
Rheumatoid arthritis (IgM rheumatoid factor contributes), Sjögren's syndrome, lupus and systemic sclerosis raise IgM polyclonally, often with IgG and IgA.
Chronic infections
Hepatitis C, HIV, chronic parasitic infections such as schistosomiasis and visceral leishmaniasis, and infective endocarditis sustain IgM production; hepatitis C can also drive a monoclonal IgM with cryoglobulinemia.
Cold agglutinin disease and cryoglobulinemia
Monoclonal IgM that binds red cells in the cold (causing hemolytic anemia and blue fingers) or precipitates in the cold (causing purpura, joint pain and kidney disease); often linked to Waldenström, lymphoma or hepatitis C.
Hyper-IgM syndromes
Rare inherited defects of class switching (most often CD40 ligand deficiency in boys) in which IgM is normal or high while IgG and IgA are very low, presenting in infancy with severe infections.
Congenital infection in newborns
A cord-blood or neonatal IgM above about 20 mg/dL suggests infection acquired in the womb, such as cytomegalovirus, toxoplasmosis, rubella or syphilis, and prompts specific testing.
Other lymphomas and chronic lymphocytic leukemia
Marginal zone lymphoma and CLL can secrete a small monoclonal IgM; nephrotic syndrome and some chronic liver diseases produce a mild polyclonal rise.
Symptoms that can go with it
- Often none; a mildly high IgM after an infection or with liver or autoimmune disease causes no symptoms of its own
- Fever, sore throat, swollen glands, fatigue or jaundice with the acute infection that triggered it
- Itching, fatigue, dry eyes and mouth, or jaundice with primary biliary cholangitis
- Fatigue, breathlessness and pallor from anemia, enlarged lymph nodes, a full feeling under the left ribs (spleen), night sweats or weight loss with Waldenström macroglobulinemia
- Headache, blurred or double vision, nosebleeds, bleeding gums, dizziness or confusion from hyperviscosity, usually when monoclonal IgM is above about 4,000 mg/dL
- Numbness, tingling and unsteadiness in the feet and hands from IgM-related neuropathy
- Fingers or toes turning blue or white in the cold, dark urine, or a purple rash on the legs from cold agglutinins or cryoglobulins
Low IgM
A low IgM on its own is a common finding that, in most people, has no clinical consequence. IgM's job is largely duplicated by IgG and by complement, and many healthy people run levels of 20 to 40 mg/dL throughout life. The interpretation changes with company: low IgM together with low IgG, or with low IgG and IgA, is a global antibody deficiency and is investigated in the same way as a low IgG, with a medication review, a search for protein loss or blood cancer, and vaccine antibody titers. Low IgM is also often the first immunoglobulin to fall after rituximab and in multiple myeloma, where the malignant clone suppresses normal plasma cells.
Selective IgM deficiency, an isolated IgM below about 20 mg/dL (definitions vary; some use the lab's lower limit) with normal IgG and IgA and normal vaccine responses, is reported in anywhere from 0.03 to 3 percent of people depending on the threshold used. Most are found by chance and stay well. A minority have recurrent sinus and chest infections, usually with encapsulated bacteria, and some have allergic or autoimmune disease. Because it can be the early stage of a broader deficiency, a repeat panel every year or two and prompt treatment of infections are the usual advice; immunoglobulin replacement is reserved for those with proven poor antibody responses and serious infections, since standard products contain almost no IgM.
Common causes
Medications
Rituximab and other anti-CD20 drugs lower IgM first and most, often for a year or more; glucocorticoids, mycophenolate, azathioprine, cyclophosphamide, some antiepileptics and chemotherapy also reduce it.
Multiple myeloma and other plasma-cell disorders
The malignant clone suppresses normal immunoglobulin production, and IgM is often the most profoundly reduced; a low IgM with an IgG or IgA spike is typical.
Chronic lymphocytic leukemia and lymphoma
Hypogammaglobulinemia develops in a quarter to two-thirds of people with CLL and typically affects IgM early; it contributes to their infection risk.
Common variable immunodeficiency
Low IgG with low IgA and/or IgM; about half of people with CVID have a low IgM, and the combination with poor vaccine responses makes the diagnosis.
Selective IgM deficiency
An isolated low IgM with normal IgG and IgA; usually asymptomatic, sometimes associated with recurrent infections, allergy or autoimmunity. Can precede CVID in a minority.
Protein loss and malnutrition
Protein-losing enteropathy, nephrotic syndrome (less so, as IgM is too large to pass the filter easily), severe burns and protein-energy malnutrition lower IgM with the other immunoglobulins.
Splenectomy and functional asplenia
The spleen houses the IgM-memory B cells that respond to encapsulated bacteria; after splenectomy, or with sickle cell disease, IgM and these responses are reduced, which is part of why pneumococcal vaccination and prompt antibiotic treatment are advised.
X-linked agammaglobulinemia and other primary immunodeficiencies
IgM is absent with IgG and IgA in boys with X-linked agammaglobulinemia; low in some combined immunodeficiencies and in Wiskott-Aldrich syndrome.
Symptoms that can go with it
- Usually none; an isolated low IgM is most often an incidental finding
- Recurrent sinus, ear or chest infections, particularly with pneumococcus or Hemophilus, when the deficiency is symptomatic or IgG is also low
- Infections that are unusually severe or slow to clear after splenectomy or during rituximab treatment
- Fatigue, bone pain, anemia or kidney problems if the low IgM is part of multiple myeloma
- Enlarged lymph nodes, night sweats or frequent infections with CLL or lymphoma
- Allergic or autoimmune symptoms (eczema, asthma, thyroid disease, joint pain) in some people with selective IgM deficiency
Read it alongside
- IgG and IgA — the pattern across the three distinguishes an isolated IgM change from a global antibody deficiency or a monoclonal protein that suppresses the others.
- Serum protein electrophoresis with immunofixation — the test that tells a polyclonal rise from an IgM M-protein and is essential for any unexplained high IgM.
- Serum viscosity — measured when monoclonal IgM is high or hyperviscosity symptoms are present; above 4 centipoise usually means plasma exchange is needed.
- Complete blood count — anemia with a high IgM suggests Waldenström or cold agglutinin hemolysis; low lymphocytes or neutrophils change the interpretation of recurrent infections.
- Alkaline phosphatase, GGT and antimitochondrial antibodies — a high IgM with cholestatic liver tests and a positive AMA is primary biliary cholangitis.
- Specific IgM serology (hepatitis A, EBV, CMV, toxoplasma) — identifies the infection behind a transient polyclonal rise.
- Free light chains and beta-2 microglobulin — part of the work-up and staging of IgM MGUS and Waldenström macroglobulinemia.
- Vaccine antibody titers — normal pneumococcal and tetanus responses in someone with a low IgM confirm the deficiency is selective and low-risk.
What usually happens next
- A mildly high IgM during or just after an infection is usually simply repeated in 2 to 3 months; it is expected to return to baseline.
- A persistently high IgM with no infection, or any IgM above about 500 mg/dL, is followed by serum protein electrophoresis with immunofixation; a polyclonal pattern is traced to liver or autoimmune disease, a monoclonal IgM leads to a blood count, viscosity, free light chains and usually a bone marrow biopsy with MYD88 testing to separate IgM MGUS from Waldenström macroglobulinemia.
- Any hyperviscosity symptoms (headache, blurred vision, nosebleeds, confusion) with a high monoclonal IgM need same-day assessment; plasma exchange brings the level down within hours.
- IgM MGUS is monitored with electrophoresis and a blood count every 6 to 12 months; asymptomatic Waldenström is watched, with treatment started for symptoms, anemia, hyperviscosity or neuropathy rather than for the IgM number alone.
- For a low IgM: expect a repeat with IgG and IgA, a medication review (rituximab, steroids, antiepileptics), and, if IgG is also low or infections are frequent, electrophoresis, a blood count and vaccine antibody titers; immunology referral follows if responses are poor.
- If IgM is low after splenectomy or during B-cell-depleting therapy, confirm pneumococcal, meningococcal and Hemophilus vaccination is up to date and ask about a plan for prompt antibiotics when feverish.
Diet, lifestyle and natural levers with evidence
What can move IgM once the cause is known. Nothing here replaces finding the cause.
Know what moves the test: timing after infection and vaccination
Strong evidenceNothing in diet or supplements raises or lowers total IgM in a useful way; the level follows what the immune system is responding to. IgM rises within 1 to 2 weeks of a new infection or a first vaccine dose and, with a half-life of 5 days, returns to baseline within 2 to 3 months. A result taken during or shortly after an acute illness is therefore expected to be high and is repeated later; a result for immunodeficiency screening is best taken when well.
Medication review
Strong evidenceRituximab lowers IgM in most people within months and the effect can persist for a year or more after the last dose; long-term prednisone, mycophenolate, azathioprine, phenytoin, carbamazepine and chemotherapy also lower it. Where a drug is the explanation and the clinical situation allows a change, IgM recovers over months as B cells return. Ursodeoxycholic acid lowers the high IgM of primary biliary cholangitis as the disease responds.
Vitamin D, if deficient, for infection risk
Moderate evidenceVitamin D does not change the IgM level, but for someone with antibody deficiency and recurrent chest infections, correcting a deficiency is a low-cost way of lowering infection risk: a meta-analysis of 25 randomised trials found daily or weekly vitamin D reduced acute respiratory infections by 12 percent overall and by about 70 percent in people starting below 10 ng/mL (25 nmol/L). It is not a substitute for vaccination or, where indicated, immunoglobulin replacement.
Keep to under 4,000 IU a day unless levels are being monitored; large bolus doses did not reduce infections in the trials.
Adequate protein and energy intake
Preliminary evidenceSevere protein-energy malnutrition lowers all immunoglobulins and antibody responses, and refeeding restores them over weeks in studies of malnourished children and adults. This is relevant after bariatric surgery, with eating disorders, in frailty and in advanced illness; an intake of about 1 to 1.2 g of protein per kilogram a day is the usual target in older adults. In a well-nourished person extra protein does not raise IgM.
When to see a clinician promptly
- A high IgM with headache, blurred or double vision, nosebleeds, bleeding gums, dizziness or confusion: possible hyperviscosity syndrome, which is an emergency needing plasma exchange.
- A high IgM with unexplained anemia, enlarged lymph nodes, a swollen spleen, night sweats or weight loss, which may indicate Waldenström macroglobulinemia or lymphoma.
- A low IgM (particularly with a low IgG, after splenectomy or on rituximab) with fever, a productive cough, breathlessness, a stiff neck or a fast heart rate: antibody-deficient people can develop sepsis or meningitis quickly.
- Numbness, tingling or unsteadiness in the feet and hands with a monoclonal IgM, which can be an IgM-related neuropathy that is treatable if caught early.
- Fingers or toes turning blue in the cold, dark urine, or a new purple rash on the legs, which suggest cold agglutinins or cryoglobulins and need assessment.
- A raised IgM in a newborn, which prompts urgent testing for infections acquired before birth.
Frequently asked questions
What is a normal IgM level?
For adults, about 40 to 230 mg/dL (0.4 to 2.3 g/L), with women averaging about 20 percent higher than men and labs varying in their exact limits. Newborns have very little (under about 20 mg/dL) because IgM cannot cross the placenta, and children reach adult values by about age 10. A result a little outside the range in someone who feels well, especially soon after an infection, is usually repeated rather than acted on.
What does a high IgM mean?
Most often that you have had a recent infection: IgM is the first antibody made, rises within one to two weeks, and settles within two to three months. Chronic causes include primary biliary cholangitis, rheumatoid arthritis and other autoimmune diseases, and chronic infections such as hepatitis C. The important thing to exclude when the rise is persistent or large is a monoclonal IgM from IgM MGUS or Waldenström macroglobulinemia, which is why protein electrophoresis is usually the next test.
What does a low IgM mean?
On its own, usually very little; many healthy people have a low IgM and never have a problem. It matters when IgG or IgA is also low, which points to a broader antibody deficiency, or when it follows rituximab, multiple myeloma, CLL or splenectomy, where it adds to infection risk. Selective IgM deficiency (an isolated low IgM with normal vaccine responses) is managed with watchfulness, vaccination and prompt treatment of infections rather than with immunoglobulin.
What is the difference between IgM and IgG?
IgM is the first antibody made in a new infection and fades within months; IgG is made a few weeks later and lasts for years or life. On an infection test, a positive IgM means a recent or current infection, a positive IgG with negative IgM means past infection or vaccination, and both positive means recent infection in transition. IgM tests produce more false positives (rheumatoid factor and cross-reacting viral antibodies are common reasons), so a lone positive IgM is often repeated or confirmed by another method. On a total immunoglobulin panel the two are measured as overall amounts, not against any specific germ.
What IgM level causes hyperviscosity?
Symptoms usually appear when a monoclonal IgM exceeds about 4,000 mg/dL (40 g/L), corresponding to a serum viscosity above about 4 centipoise, though the threshold varies between people and someone who has had hyperviscosity once tends to get it again at the same level. Polyclonal rises almost never reach this range. Warning signs are headache, blurred vision, nosebleeds, bleeding gums, dizziness and confusion; treatment is plasma exchange followed by therapy for the underlying Waldenström macroglobulinemia.
Does high IgM mean I have cancer?
Usually not. Most high IgM results are polyclonal responses to infection, liver disease or autoimmune disease and settle or track the underlying condition. A monoclonal IgM is found in a minority; even then, most are IgM MGUS, which progresses to Waldenström macroglobulinemia or lymphoma at about 1.5 percent per year. Waldenström itself is a slow-growing lymphoma, often watched without treatment for years. Protein electrophoresis with immunofixation, and if needed a marrow biopsy, settle the question.
Why is IgM tested in newborns?
Because a baby's own IgM is almost the only antibody it has made itself: maternal IgG crosses the placenta but IgM does not. A cord-blood or newborn IgM above about 20 mg/dL suggests the baby's immune system responded to an infection before birth, such as cytomegalovirus, toxoplasmosis, rubella or syphilis, and prompts specific tests. Specific IgM tests (for example toxoplasma IgM) are used in the same way, with the caveat that they can be falsely positive.
Can I raise a low IgM naturally?
No diet or supplement raises IgM. If a medication such as rituximab or a steroid is the cause, levels recover over months once it is stopped or reduced, when that is possible. What you can do is lower infection risk: keep inactivated vaccines up to date (pneumococcal, influenza, COVID-19, and meningococcal and Hemophilus if you have no spleen), correct vitamin D or nutritional deficiencies, treat infections early, and have a repeat immunoglobulin panel every year or two to check that IgG is not falling as well.
References
- Immunoglobulins blood test. MedlinePlus, US National Library of Medicine (2023)View source
- Waldenstrom macroglobulinemia. Mayo Clinic (2024)View source
- Macroglobulinemia. Merck Manual Professional Version (2024)
- Stone MJ, Bogen SA. Evidence-based focused review of management of hyperviscosity syndrome. Blood (2012)
- Gertz MA. Waldenström macroglobulinemia: 2023 update on diagnosis, risk stratification, and management. American Journal of Hematology (2023)
- Kyle RA, Therneau TM, Rajkumar SV, et al.. Long-term follow-up of IgM monoclonal gammopathy of undetermined significance. Blood (2003)
- Louis AG, Gupta S. Primary selective IgM deficiency: an ignored immunodeficiency. Clinical Reviews in Allergy and Immunology (2014)
- Bonilla FA, Khan DA, Ballas ZK, et al.. Practice parameter for the diagnosis and management of primary immunodeficiency. Journal of Allergy and Clinical Immunology (2015)
- Lindor KD, Bowlus CL, Boyer J, Levy C, Mayo MJ. Primary biliary cholangitis: 2018 practice guidance from the American Association for the Study of Liver Diseases. Hepatology (2019)
- Gonzalez-Quintela A, Alende R, Gude F, et al.. Serum levels of immunoglobulins (IgG, IgA, IgM) in a general adult population and their relationship with alcohol consumption, smoking and common metabolic abnormalities. Clinical and Experimental Immunology (2008)
- Martineau AR, Jolliffe DA, Hooper RL, et al.. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ (2017)
- Patel SY, Carbone J, Jolles S. Secondary immunodeficiency: diagnosis and management. Frontiers in Immunology (2019)
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