What is the serum albumin‑to‑globulin ratio and how should an albumin‑to‑globulin ratio of 1.57 be interpreted in a 22‑year‑old adult with allergic urticaria and swollen feet and hands?

Albumin-to-Globulin Ratio: Definition and Interpretation in a 22-Year-Old with Allergic Urticaria and Edema

What is the A:G Ratio?

The albumin-to-globulin (A:G) ratio is calculated by dividing serum albumin by serum globulin (total protein minus albumin), and serves as a screening tool to detect abnormal protein distribution that may indicate liver disease, immune disorders, or protein-losing conditions. 1, 2

• The ratio reflects the balance between albumin (produced by the liver) and globulins (primarily immunoglobulins produced by plasma cells), with normal values typically ranging from 1.0 to 2.5 1, 2
• Calculated globulin is derived by subtracting albumin from total protein on standard liver function tests, making this an inexpensive and readily available screening parameter 2

Interpretation of Your A:G Ratio of 1.57

An A:G ratio of 1.57 falls within the normal range (1.0–2.5) and does not indicate significant protein abnormality, liver disease, or immune dysfunction in isolation. 1, 2

• This ratio suggests that your albumin and globulin levels are proportionally balanced, with no evidence of the albumin-globulin reversal (A:G < 1.0) that characterizes severe liver disease or marked hypergammaglobulinemia 1, 3
• In the context of allergic urticaria with peripheral edema (swollen hands and feet), a normal A:G ratio helps exclude nephrotic syndrome, severe liver disease, or protein-losing enteropathy as underlying causes 2

Clinical Context: Allergic Urticaria with Edema

Your presentation of allergic urticaria with peripheral edema most likely represents angioedema—a deeper dermal and subcutaneous swelling that commonly accompanies urticaria—rather than a systemic protein-losing condition, given the normal A:G ratio. 2

What the Normal A:G Ratio Rules Out:

• Nephrotic syndrome would typically show hypoalbuminemia with a low or reversed A:G ratio due to massive urinary albumin loss 4
• Severe liver disease (cirrhosis, chronic hepatitis) would demonstrate A:G reversal (ratio < 1.0) due to decreased albumin synthesis and increased globulins 1, 3
• Protein-losing enteropathy would show low albumin with proportionally low globulins, potentially maintaining a normal ratio but with absolute hypoproteinemia 2

Additional Evaluation Needed:

• Measure serum albumin and total protein absolute values—a normal A:G ratio can still occur with proportional decreases in both albumin and globulin (hypoproteinemia), which would be clinically significant 2
• Obtain urinalysis with albumin-to-creatinine ratio to exclude occult kidney disease, particularly if edema persists; an ACR < 30 mg/g would rule out significant proteinuria 4, 5
• Check complement levels (C3, C4) and tryptase if urticaria is recurrent or severe, as complement-mediated angioedema or mast cell disorders can present with similar symptoms but would not alter the A:G ratio 2

When A:G Ratio Becomes Clinically Significant

• A:G ratio < 1.0 (reversed ratio) indicates either severe hypoalbuminemia or marked hypergammaglobulinemia, seen in cirrhosis (72.3% of hepatic disease cases show globulin rise with low albumin) or chronic inflammatory/autoimmune conditions 1, 3
• Calculated globulin ≤ 20 g/L has 82.5% positive predictive value for hypogammaglobulinemia (IgG ≤ 5.7 g/L), warranting immunoglobulin quantification 2
• Calculated globulin ≥ 42 g/L should prompt serum protein electrophoresis, as 42.3% of such patients have paraproteins (monoclonal gammopathies) 2

Common Pitfalls to Avoid

• Do not interpret the A:G ratio in isolation—always review absolute albumin and total protein values, as a normal ratio can mask proportional decreases in both fractions 2
• Do not assume edema is cardiac or renal without checking albumin levels—hypoalbuminemia < 3.0 g/dL is required for oncotic pressure-driven edema, which your normal A:G ratio makes unlikely 4
• Do not overlook transient causes of altered ratios—acute inflammation, dehydration, or recent intravenous immunoglobulin can temporarily shift the A:G ratio without indicating chronic disease 2