A/G ratio blood test: what a high or low albumin/globulin ratio means
Albumin/globulin ratio (A/G ratio) · Comprehensive metabolic panel (CMP), liver panel · reported in Ratio (no units); albumin and globulin in g/dL
The albumin/globulin ratio (A/G ratio) is a calculated number on a metabolic or liver panel that compares the two main groups of protein in your blood: albumin, the single protein the liver makes to hold fluid in the circulation and carry hormones and drugs, and globulins, the mixed group that includes antibodies, transport proteins and inflammatory proteins. The lab divides albumin by globulin (total protein minus albumin). In healthy adults albumin outweighs globulin, so the ratio is usually between about 1.1 and 2.5, with small differences between laboratories.
A low A/G ratio is far more common than a high one and is the result people usually search for. It means albumin has fallen, globulins have risen, or both. Chronic liver disease, chronic infection, autoimmune disease, kidney protein loss, poor nutrition and the inflammation of any serious illness all lower it; so does a monoclonal protein from multiple myeloma or its benign precursor MGUS. A high A/G ratio nearly always means globulins are low, which can reflect an immune deficiency or immunosuppressive medication, though a mildly high ratio with a normal total protein is usually not significant.
The ratio is a pointer, not a diagnosis. Because dehydration and dilution move albumin and globulin together, the A/G ratio is more stable than total protein, which makes it a useful first clue that one fraction is genuinely out of proportion. What it cannot do is say which globulin is high or why; that is the job of serum protein electrophoresis, immunofixation and free light chains, which are ordered when the ratio is low and the globulin level is raised.
A/G ratio at a glance
- What it is: albumin divided by globulin (total protein minus albumin); a calculation, not a separate blood test.
- Normal (adults): about 1.1–2.5; many labs print 1.0–2.2 or 1.2–2.2. Albumin is normally 3.5–5.0 g/dL and globulin 2.0–3.5 g/dL.
- Low A/G ratio (below about 1.0): high globulins (chronic infection, autoimmune disease, liver disease, MGUS, myeloma) or low albumin (liver disease, kidney or gut protein loss, malnutrition, inflammation).
- High A/G ratio (above about 2.5): usually low globulins from immune deficiency, corticosteroids, rituximab or chemotherapy; often of no significance if total protein is normal.
- A globulin above about 4 g/dL with a low ratio is the usual trigger for serum protein electrophoresis and free light chains to exclude a monoclonal protein.
- Next step: look at albumin and globulin separately, repeat if borderline, and add liver tests, CRP, a urine protein check and electrophoresis as the pattern directs.
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What A/G ratio measures
The laboratory measures total protein with the biuret method and albumin with a dye-binding method, subtracts one from the other to get globulin, then divides albumin by globulin. With an albumin of 4.2 g/dL and a total protein of 7.0, globulin is 2.8 and the ratio is 1.5. Because globulin is derived rather than measured, small assay differences in albumin shift the ratio, which is one reason reference limits vary between labs and why a ratio of 2.3 at one lab and 2.6 at another can describe the same blood.
The albumin side reflects liver synthesis, losses through the kidney, gut and skin, nutrition and, above all, inflammation, which lowers albumin within days. The globulin side is dominated by the immunoglobulins IgG, IgA and IgM made by plasma cells, plus liver-made alpha and beta globulins such as haptoglobin, transferrin and complement. A ratio below 1.0 therefore usually means the immune system has been producing a lot of antibody for a long time, the liver is failing to make albumin, or both, which is why cirrhosis is the textbook cause.
Hydration status, posture and tourniquet time change total protein by up to 0.5 to 0.8 g/dL but change albumin and globulin proportionally, so the A/G ratio barely moves. Fasting is not needed. Pregnancy lowers albumin more than globulin, so the ratio drifts down in the third trimester without meaning anything is wrong.
Normal range for A/G ratio
Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.
| Group | Typical range (Ratio (no units); albumin and globulin in g/dL) | Notes |
|---|---|---|
| Adults, typical reference range | About 1.1–2.5 | Labs variously print 1.0–2.2, 1.1–2.2 or 1.2–2.5; use the range on your report. |
| Albumin component | 3.5–5.0 g/dL | The numerator. Rarely high except with dehydration; falls with liver disease, protein loss, malnutrition and inflammation. |
| Globulin component (calculated) | 2.0–3.5 g/dL | The denominator. Total protein minus albumin. |
| Mildly low | About 0.9–1.1 | Common with mild inflammation, early liver disease, chronic infection or pregnancy; often repeated before further work-up. |
| Clearly low | Below 0.9 | Albumin is below globulin. Expect liver tests, CRP, urine protein and serum protein electrophoresis. |
| Low with globulin above 4 g/dL | Any ratio below 1.0 | The pattern that prompts electrophoresis, immunofixation and free light chains to exclude MGUS, myeloma or Waldenström macroglobulinemia. |
| Mildly high | About 2.3–2.8 with normal total protein | Usually globulin at the low end of normal; rarely significant on its own. |
| Clearly high | Above about 2.8, or globulin below 2.0 g/dL | Suggests low immunoglobulins; IgG, IgA and IgM levels are measured, and medication history is reviewed. |
| Pregnancy, third trimester | Often 1.0–1.3 | Albumin falls more than globulin as plasma volume expands; returns to usual values after delivery. |
High A/G ratio
A high A/G ratio means albumin is high relative to globulin. Albumin itself seldom rises above about 5.0 g/dL except from dehydration, and dehydration raises globulin by the same proportion, so the ratio stays put. In practice a high ratio almost always means globulins are low: below about 2.0 g/dL on the calculated figure. If total protein is normal and the ratio is only modestly raised (2.3 to 2.8), this is usually a healthy person whose immunoglobulins sit at the low end of normal, and no action is needed.
A clearly high ratio with a low globulin raises the question of hypogammaglobulinemia. The acquired causes are more common than the inherited ones: long-term corticosteroids, rituximab and other B-cell-depleting drugs, chemotherapy, and blood cancers such as chronic lymphocytic leukemia and myeloma, which suppress normal antibody production. Nephrotic syndrome and protein-losing enteropathy lose immunoglobulins too, though they usually lose albumin faster, so the ratio is more often low than high. Inherited immune deficiencies such as common variable immunodeficiency (about 1 in 25,000 people) and X-linked agammaglobulinemia present with recurrent sinus, ear and chest infections and are confirmed by measuring IgG, IgA and IgM directly.
A high ratio can also be a quirk of the arithmetic. Because globulin is calculated, a slightly high albumin assay result and a slightly low total protein result combine into a lower globulin and a higher ratio, and reference ranges for the ratio differ between labs more than for most tests. A repeat sample and a look at the absolute globulin value resolve most of these.
Common causes
Low immunoglobulins from medication
Corticosteroids, rituximab and similar B-cell-depleting antibodies, mycophenolate, cyclophosphamide and many chemotherapy regimens lower IgG, IgA and IgM for months after treatment, pushing globulin below 2 g/dL.
Primary immune deficiency
Common variable immunodeficiency and X-linked agammaglobulinemia produce very low immunoglobulins, with recurrent bacterial infections of the sinuses, ears and lungs, chronic diarrhea and poor response to vaccines.
Blood cancers that suppress normal antibodies
Chronic lymphocytic leukemia and lymphoma often lower normal immunoglobulins; myeloma can do the same even while producing a monoclonal spike, so the ratio may be high or low depending on the balance.
Protein loss that affects globulins
Nephrotic syndrome and protein-losing enteropathy lose IgG as well as albumin; when the albumin loss is modest, the ratio can rise rather than fall.
Excess cortisol
Cushing's syndrome and high-dose steroid treatment reduce immunoglobulin production and modestly raise albumin, lifting the ratio.
Dehydration with a disproportionately high albumin
Severe fluid loss occasionally raises the measured albumin more than the calculated globulin, producing a transiently high ratio that corrects with rehydration.
Assay and rounding effects
Globulin is total protein minus albumin, so small measurement differences in each are amplified in the ratio; a ratio of 2.6 with a globulin of 1.9 g/dL and a normal total protein is usually not a disease.
Symptoms that can go with it
- Usually none; a mildly high A/G ratio is an incidental finding
- Recurrent sinus, ear or chest infections, or infections that need repeated courses of antibiotics, when immunoglobulins are low
- Chronic diarrhea or persistent Giardia infection with immune deficiency
- Thirst, dark urine or dizziness when dehydration is the cause
- Swollen lymph nodes, fatigue or easy bruising with an underlying blood cancer
- Weight gain, rounded face and easy bruising with excess cortisol
Low A/G ratio
A low A/G ratio means albumin has fallen, globulins have risen, or both. Looking at the two numbers separately tells you which. A low albumin with normal globulin points to liver disease, loss of protein through the kidneys or gut, poor nutrition, heart failure or the inflammation of an acute illness, in which albumin drops within days while CRP rises. A normal albumin with a high globulin points to long-standing immune activation: chronic infections such as HIV, hepatitis B and C and tuberculosis; autoimmune diseases such as rheumatoid arthritis, lupus and Sjögren's; sarcoidosis; or a monoclonal protein. Both together, a low albumin and a high globulin, is the classic picture of cirrhosis.
The distinction that matters most is between a polyclonal and a monoclonal globulin rise. Serum protein electrophoresis separates the globulins into alpha, beta and gamma fractions; inflammation produces a broad, diffuse increase, whereas a single clone of plasma cells produces a narrow spike. MGUS, found in about 3 percent of people over 50, produces a modest spike and no symptoms; multiple myeloma produces a larger one together with anemia, high calcium, kidney impairment or bone pain. A globulin above about 4 g/dL, or a total protein minus albumin above 4, is the usual threshold at which electrophoresis, immunofixation and serum free light chains are ordered.
In large population studies a low A/G ratio also tracks long-term risk. A Korean cohort of about 27,000 healthy adults found that those with a ratio in the lowest range (under about 1.1) had roughly twice the later cancer incidence and cancer mortality of those with a ratio above 1.5, and meta-analyses in people already diagnosed with cancer link a lower pre-treatment ratio with worse survival. The ratio is reflecting chronic inflammation and poorer nutrition rather than causing anything, and for an individual it is a reason to find the explanation, not a prognosis.
Common causes
Cirrhosis and chronic liver disease
The failing liver makes less albumin and clears fewer gut-derived antigens, so immunoglobulins rise; a globulin of 4 to 5 g/dL with an albumin under 3.5 g/dL is typical. IgA is prominent in alcohol-related disease, IgG in autoimmune hepatitis and IgM in primary biliary cholangitis.
Multiple myeloma, MGUS and Waldenström macroglobulinemia
A plasma cell clone secretes a single immunoglobulin that raises globulin and, in myeloma, often suppresses albumin; the ratio can fall well below 0.8. Anemia, raised calcium, kidney impairment and bone pain distinguish myeloma from MGUS.
Chronic infection
HIV, chronic hepatitis B and C, tuberculosis, endocarditis, osteomyelitis and chronic parasitic infections drive months of antibody production, raising polyclonal IgG and lowering albumin through inflammation.
Autoimmune and inflammatory disease
Rheumatoid arthritis, systemic lupus, Sjögren's syndrome, autoimmune hepatitis, sarcoidosis and inflammatory bowel disease all raise immunoglobulins and depress albumin in proportion to disease activity.
Nephrotic syndrome and other kidney protein loss
More than 3.5 g of protein a day lost in the urine lowers albumin below 3.0 g/dL; globulins fall less, so the ratio drops. Swelling, high cholesterol and foamy urine accompany it.
Malnutrition and malabsorption
Inadequate intake, anorexia nervosa, alcohol dependence, celiac disease, Crohn's disease and bariatric surgery reduce albumin synthesis over weeks while globulins are relatively preserved.
Acute illness, surgery and sepsis
Albumin is a negative acute-phase protein and can fall by 1 g/dL within days of a major infection, operation or injury, lowering the ratio even when globulins have not changed; it recovers over weeks.
Heart failure
Fluid retention, gut congestion and chronic inflammation combine to lower albumin; a low ratio in heart failure is a marker of more severe disease.
Pregnancy
Plasma volume rises 40 to 50 percent and albumin falls more than globulin, so the ratio commonly reaches 1.0 to 1.3 by the third trimester; it normalizes after delivery.
Symptoms that can go with it
- Often none; the ratio is usually found on a routine panel
- Swelling of the ankles, legs or abdomen when albumin is low
- Fatigue, loss of appetite, yellowing of the skin or eyes, spider veins on the chest with liver disease
- Bone pain, fractures from minor injury, recurrent infections or unexplained anemia with myeloma
- Joint pain, rashes, dry eyes and mouth, or low-grade fevers with autoimmune disease
- Night sweats, weight loss or persistent cough with chronic infection
- Foamy urine with kidney protein loss
Read it alongside
- Albumin — tells you whether the numerator is the problem; below 3.5 g/dL points to liver disease, protein loss, malnutrition or inflammation.
- Globulin — the denominator; above about 4 g/dL is the threshold for a plasma cell work-up.
- Total protein — a low ratio with a high total protein means globulins are up; a low ratio with a low total protein means albumin is down.
- Serum protein electrophoresis, immunofixation and free light chains — separate a polyclonal rise (inflammation, liver disease) from a monoclonal spike (MGUS, myeloma, Waldenström).
- IgG, IgA and IgM — quantify the immunoglobulins when globulin is high or low; low levels confirm hypogammaglobulinemia.
- ALT, AST, alkaline phosphatase, bilirubin and INR — liver injury and synthetic function behind a low albumin or high globulin.
- CRP and ESR — a high CRP explains a low albumin; a very high ESR with a modest CRP suggests a paraprotein.
- Urine protein or albumin/creatinine ratio, CBC, calcium and creatinine — kidney loss, and the anemia, hypercalcemia and kidney impairment that mark myeloma.
What usually happens next
- Look at albumin and globulin separately; the ratio is only a prompt, and the pattern (low albumin, high globulin, or both) decides what comes next.
- If the ratio is mildly low and you were recently unwell, expect a repeat in 4 to 6 weeks once the illness has settled; albumin recovers over weeks.
- A persistently low ratio with globulin above about 4 g/dL leads to serum protein electrophoresis with immunofixation, serum free light chains, IgG, IgA and IgM, a CBC, calcium and creatinine.
- A polyclonal rise prompts screening for chronic infection (HIV, hepatitis B and C), autoimmune disease (ANA, rheumatoid factor) and liver disease, depending on your history.
- A low albumin with normal globulin leads to liver tests, a urine protein check, CRP and a nutrition review; celiac serology or stool alpha-1 antitrypsin follow if the gut is suspected.
- A high ratio with globulin below 2 g/dL leads to a medication review and immunoglobulin levels; recurrent infections make that assessment more urgent.
Diet, lifestyle and natural levers with evidence
What can move A/G ratio once the cause is known. Nothing here replaces finding the cause.
Adequate protein and energy intake
Moderate evidenceWhen the albumin side is low because of poor intake or malabsorption, raising protein to 1.0 to 1.2 g per kilogram a day (1.2 to 1.5 g/kg during recovery from illness, per the PROT-AGE recommendations for older adults) supplies what the liver needs. A Cochrane review of 62 trials of protein and energy supplements in older people at risk of malnutrition found small gains in weight and fewer complications; albumin itself moves slowly, over weeks, and barely at all when inflammation rather than intake is the cause.
People with advanced kidney disease not on dialysis are usually advised to limit protein to about 0.6 to 0.8 g/kg a day; check before increasing intake.
Reducing or stopping alcohol
Moderate evidenceHeavy drinking produces the textbook low A/G pattern: albumin falls as the liver is damaged and IgA rises as the gut barrier leaks bacterial products. In alcohol-related liver disease abstinence is the strongest predictor of survival, and cohort studies show albumin and Child-Pugh scores improving over 3 to 6 months without alcohol in people whose cirrhosis is not yet advanced.
Gluten-free diet in celiac disease
Moderate evidenceUntreated celiac disease lowers albumin through malabsorption and protein loss and raises IgA; on a strict gluten-free diet the intestinal lining recovers and albumin and other nutritional markers normalize within 6 to 12 months in most people, while tissue transglutaminase antibodies fall. The same principle applies to controlling Crohn's disease and other causes of protein-losing enteropathy.
Lowering chronic inflammation: weight loss, activity and a Mediterranean-style diet
Preliminary evidenceAlbumin falls and acute-phase globulins rise with chronic low-grade inflammation. Weight loss lowers CRP by about 0.13 mg/L per kilogram lost in a meta-analysis of 33 studies, and a Mediterranean diet lowered CRP by around 1 mg/L across 15 trials, but no trial has used the A/G ratio as an endpoint, so the effect on the ratio itself is inferred rather than measured and is likely small.
When to see a clinician promptly
- A low A/G ratio with a globulin above 4 g/dL together with bone pain, unexplained anemia, kidney problems or frequent infections: myeloma needs to be excluded within days.
- A low ratio with swelling of the legs or abdomen, breathlessness or foamy urine, which can mean nephrotic syndrome or advanced liver disease.
- Jaundice, confusion, vomiting blood or black stools with a low albumin: possible liver failure or gastrointestinal bleeding, needing same-day care.
- A high ratio with low globulin and a history of recurrent chest, sinus or ear infections, to have immunoglobulin levels measured.
- Unexplained weight loss, night sweats, persistent fever or new lumps alongside any abnormal ratio.
- Blurred vision, nosebleeds, headaches or confusion with a very high globulin, which can indicate hyperviscosity and is treated urgently.
Frequently asked questions
What is a normal A/G ratio?
For adults, roughly 1.1 to 2.5, meaning albumin is somewhat higher than globulin. Many labs print 1.0 to 2.2 or 1.2 to 2.2, and because globulin is calculated rather than measured, the ratio varies more between labs than most tests. A value just outside the printed range with normal albumin and globulin levels is usually not important.
What does a low A/G ratio mean?
Albumin is low, globulins are high, or both. Common reasons are chronic liver disease, chronic infections such as HIV or hepatitis C, autoimmune diseases, kidney protein loss, poor nutrition and the inflammation of any serious illness. Less commonly it reflects a monoclonal protein from MGUS or multiple myeloma, which is why a low ratio with a high globulin leads to protein electrophoresis.
What does a high A/G ratio mean?
Almost always that globulins are low, since albumin rarely rises on its own. If total protein is normal and the ratio is only modestly high, it usually has no significance. A clearly high ratio with globulin under 2 g/dL suggests low immunoglobulins, from corticosteroids, rituximab, chemotherapy, certain blood cancers or a primary immune deficiency, particularly if you get frequent infections.
Is an A/G ratio of 1.0 bad?
It is at or just below the lower limit at most labs and means albumin and globulin are about equal. On its own it is not dangerous, but it is a prompt to look at the two numbers: a globulin above 4 g/dL or an albumin below 3.5 g/dL needs an explanation. If you were recently ill, pregnant or have a known inflammatory condition, that may be the whole story, and a repeat in a few weeks is reasonable.
Does a low A/G ratio mean cancer?
Usually not. Most low ratios come from liver disease, infection, inflammation, kidney loss or nutrition. The cancer-related cause is a monoclonal protein; its benign form, MGUS, affects about 3 percent of people over 50 and progresses at about 1 percent a year, while myeloma is much rarer and usually brings anemia, high calcium, kidney impairment or bone pain. Population studies link a very low ratio with higher long-term cancer risk, but that reflects chronic inflammation rather than a hidden tumor in any one person.
How is the A/G ratio calculated?
Globulin is worked out first as total protein minus albumin, then albumin is divided by globulin. For example, total protein 7.2 g/dL and albumin 4.4 g/dL give a globulin of 2.8 and a ratio of 1.6. Because every step uses the same two measurements, a small error in either shifts the ratio noticeably, so borderline results are usually repeated.
Can dehydration change the A/G ratio?
Very little. Dehydration concentrates albumin and globulins by the same proportion, so total protein rises but the ratio stays roughly the same. That is one of the ratio's advantages over total protein. The exception is severe dehydration with a disproportionate rise in measured albumin, which can nudge the ratio up until fluids are replaced.
How do you raise a low A/G ratio?
By treating what caused it. If albumin is low from poor intake, 1.0 to 1.2 g of protein per kilogram a day over weeks helps; if it is low from liver disease, kidney loss, a gut condition or inflammation, it rises only as that condition improves. If globulins are high from infection, autoimmune disease or liver disease, they fall as the underlying problem is controlled. There is no supplement that changes the ratio directly.
References
- Total protein and albumin/globulin (A/G) ratio. MedlinePlus, US National Library of Medicine (2022)View source
- Busher JT. Serum albumin and globulin. In: Clinical Methods: The History, Physical, and Laboratory Examinations, 3rd edition. Butterworths (NCBI Bookshelf) (1990)View source
- O'Connell TX, Horita TJ, Kasravi B. Understanding and interpreting serum protein electrophoresis. American Family Physician (2005)
- Suh B, Park S, Shin DW, et al.. Low albumin-to-globulin ratio associated with cancer incidence and mortality in generally healthy adults. Annals of Oncology (2014)
- Lv GY, An L, Sun XD, Hu YL, Sun DW. Pretreatment albumin to globulin ratio can serve as a prognostic marker in human cancers: a meta-analysis. Clinica Chimica Acta (2018)
- Kyle RA, Therneau TM, Rajkumar SV, et al.. Prevalence of monoclonal gammopathy of undetermined significance. New England Journal of Medicine (2006)
- Rajkumar SV, Dimopoulos MA, Palumbo A, et al.. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncology (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)
- Soeters PB, Wolfe RR, Shenkin A. Hypoalbuminemia: pathogenesis and clinical significance. Journal of Parenteral and Enteral Nutrition (2019)
- Bauer J, Biolo G, Cederholm T, et al.. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association (2013)
- Selvin E, Paynter NP, Erlinger TP. The effect of weight loss on C-reactive protein: a systematic review. Archives of Internal Medicine (2007)
- Overview of plasma cell disorders. Merck Manual Professional Version (2024)
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