IgA Test: Purpose, Normal Range and Price

The Immunoglobulin A test is a blood test that measures the level of IgA, the second most abundant antibody class in the bloodstream and the dominant immunoglobulin at mucosal surfaces throughout the body. IgA exists in two distinct forms: serum IgA, which circulates in the blood as a monomer, and secretory IgA, which is found in mucosal secretions including saliva, tears, breast milk, intestinal fluid, and respiratory and genitourinary tract secretions. Secretory IgA serves as the primary first-line immune defence at mucosal surfaces, neutralising pathogens, preventing their adherence to epithelial cells, and blocking their entry into the systemic circulation before infection can be established. The liver produces the majority of serum IgA, while mucosal plasma cells produce secretory IgA locally at epithelial surfaces. IgA plays a critical role in maintaining the delicate immune homeostasis of the gut, respiratory tract, and other mucosal sites, preventing both pathogenic invasion and inappropriate inflammatory responses to commensal microorganisms. Deficiency of IgA, known as selective IgA deficiency, is the most common primary immunodeficiency disorder in humans, affecting approximately one in 300 to 500 individuals in some populations, and is frequently associated with recurrent respiratory and gastrointestinal infections, autoimmune conditions, and allergic disease. In India, IgA testing holds particular relevance in the context of coeliac disease diagnosis, where total serum IgA must be measured alongside the TTG IgA antibody test to exclude selective IgA deficiency, which would otherwise produce a falsely negative coeliac antibody result and delay diagnosis. The test is performed on a small blood sample drawn from a vein and completed in under five minutes.

Doctors prescribe an IgA test in the following situations: Diagnosing selective IgA deficiency in patients with recurrent sinopulmonary infections, recurrent gastrointestinal infections, and a history of anaphylactic transfusion reactions where absent or markedly reduced serum IgA confirms the most common primary immunodeficiency and guides clinical management including avoidance of IgA-containing blood products. Evaluating coeliac disease serology where total serum IgA is an essential co-test ordered alongside TTG IgA antibodies to confirm adequate IgA production, as selective IgA deficiency causes false negative TTG IgA results and patients with low total IgA require alternative antibody testing using IgG-based coeliac markers for accurate diagnosis. Investigating IgA nephropathy, the most common primary glomerulonephritis worldwide, in patients with recurrent haematuria, proteinuria, and declining kidney function where elevated serum IgA alongside characteristic renal biopsy findings of mesangial IgA deposition confirms this diagnosis and guides nephroprotective treatment decisions. Assessing IgA myeloma and other plasma cell dyscrasias where a monoclonal IgA spike detected on serum protein electrophoresis is quantified through IgA measurement and monitored serially to track disease burden, treatment response, and progression in patients with confirmed or suspected plasma cell malignancy. Monitoring patients with common variable immunodeficiency and other combined immunodeficiency disorders where IgA measurement alongside IgG and IgM provides a complete humoral immune profile, guides immunoglobulin replacement therapy decisions, and monitors immune reconstitution following treatment. Evaluating autoimmune conditions including systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease where IgA abnormalities contribute to the immunological profile and where IgA deficiency co-occurring with autoimmune disease has important implications for treatment safety, particularly regarding biological therapies.

The IgA test measures the total concentration of Immunoglobulin A in the blood serum, expressed in milligrams per decilitre (mg/dL). Normal reference ranges vary by age, with adult values stabilising after adolescence. Normal ranges for adults are 70 to 400 mg/dL. Values in children are age-dependent, progressively rising from very low levels at birth toward adult reference ranges by mid-adolescence. Gender differences in adult IgA levels are not clinically significant. Normal (70 to 400 mg/dL) A result within the normal adult range indicates adequate IgA production and intact mucosal immune defence capacity. In the context of coeliac disease testing, a normal total IgA confirms that a negative TTG IgA result is reliable and not attributable to IgA deficiency, providing confidence in the serological exclusion of coeliac disease. Low IgA (Below 70 mg/dL) A low IgA result indicates partial IgA deficiency, while a result below 7 mg/dL in an adult meets the diagnostic criterion for selective IgA deficiency. Low IgA is associated with increased susceptibility to mucosal infections, higher rates of autoimmune disease, allergic conditions, and a significant risk of anaphylactic reactions to IgA-containing blood products and intravenous immunoglobulin preparations containing IgA. Elevated IgA (Above 400 mg/dL) An elevated total IgA may indicate chronic infection, chronic liver disease including alcoholic liver disease and cirrhosis, autoimmune conditions, inflammatory bowel disease, or a monoclonal IgA-producing plasma cell dyscrasia. Markedly elevated IgA, particularly with a monoclonal pattern on protein electrophoresis, warrants haematological investigation to exclude IgA myeloma or related plasma cell disorders requiring specialist management.

No fasting is required for the IgA test, as food and fluid intake do not affect immunoglobulin concentrations in the blood. The test can be performed at any time of day and is commonly ordered as part of a broader immunological, coeliac disease, or renal investigation panel without any specific dietary preparation needed beforehand. Inform your doctor about all medications currently being taken, particularly immunosuppressive agents, corticosteroids, chemotherapy drugs, biological therapies, and intravenous immunoglobulin replacement therapy, as these directly suppress or alter immunoglobulin production and levels, and are essential context for accurate interpretation of a low or abnormal IgA result. If the IgA test is being ordered as part of a coeliac disease workup, inform your doctor whether you are currently consuming a gluten-containing diet, as gluten-free dietary restriction reduces coeliac antibody levels but does not significantly alter total serum IgA itself. Staying well hydrated before the blood draw facilitates easier venous access and a smooth collection experience, particularly when IgA is being ordered alongside a broader immunological or metabolic panel.

If you are booking through the SecondMedic platform the IgA test price starts at approximately Rs. 830. The exact price will be confirmed at the time of booking through SecondMedic. If your doctor has prescribed multiple tests alongside IgA, SecondMedic health packages include IgA as part of a broader comprehensive immunoglobulin panel at a significantly lower combined price.

SecondMedic offers convenient home sample collection for the IgA test across India, making it easy to get tested without visiting a diagnostic centre. Home collection is available free of charge for orders above Rs. 300. A trained phlebotomist will visit your preferred address between 7 AM and 10 PM, seven days a week, including Sundays and public holidays. Your blood sample is processed at NABL-accredited partner laboratories, and your report is delivered within 24 hours directly to your WhatsApp and email.