Immunoglobulin tests measure the amount and pattern of antibodies (immunoglobulins) in blood—typically IgG, IgA, IgM (and sometimes IgE and IgD)—and detect abnormal monoclonal proteins or excess free light chains using methods such as serum protein electrophoresis, immunofixation and serum free light‑chain assays.

Abnormal results — a large monoclonal “M‑spike,” a single disproportionately elevated immunoglobulin class, or an abnormal kappa/lambda light‑chain ratio — can indicate a plasma‑cell neoplasm (for example multiple myeloma, Waldenström’s macroglobulinemia) or a precursor state (MGUS). However, these tests are screening/diagnostic aids rather than definitive proof of cancer; results must be interpreted with clinical findings and usually require further evaluation (repeat tests, bone marrow biopsy, imaging) to confirm a malignancy.

Samples for immunoglobulin testing are most commonly collected as a blood draw (venipuncture) by a trained phlebotomist into a serum or plasma tube; the lab separates the serum/plasma and measures IgG, IgA, IgM (and sometimes IgE or subclasses). Some at‑home or point‑of‑care options use a capillary fingerstick to collect a small blood spot or microtube when venous access isn’t needed.

No special fasting is usually required; follow any kit or clinic instructions about medication, recent immunoglobulin therapy, or recent vaccinations that could affect results. Collected samples are labeled, processed, and sent to the testing laboratory according to the provider’s handling and shipping instructions.

Immunoglobulin (antibody) tests measure your personal levels of major antibody types (IgG, IgA, IgM and sometimes IgE) and can indicate whether your immune system is unusually low or producing an excess or an abnormal pattern of antibodies. Persistently very low levels suggest an increased infection risk or an immune‑deficiency process, while very high total immunoglobulins or a single dominant (monoclonal) antibody pattern can be a sign of a plasma‑cell or B‑cell disorder (ranging from benign monoclonal gammopathy to conditions like multiple myeloma or Waldenström macroglobulinemia).

However, immunoglobulin results alone do not diagnose cancer. Abnormal results commonly have noncancer causes (infections, autoimmune disease, recent vaccinations, medications) and usually prompt additional tests—serum protein electrophoresis, immunofixation, free light‑chain assay, imaging or bone marrow evaluation—if a clonal process is suspected. Discuss your specific results with your clinician to understand what they mean for your personal cancer risk and whether further evaluation is recommended.

Immunoglobulin tests (serum protein electrophoresis, immunofixation, and serum free light‑chain assays) can reliably detect abnormal monoclonal proteins that are characteristic of disorders such as multiple myeloma or monoclonal gammopathy of undetermined significance, and they are useful for screening and monitoring these conditions. Their accuracy depends on the specific assay—immunofixation and free light‑chain testing are more sensitive than basic electrophoresis and the combination of tests detects more cases than any single assay.

However, these tests are not a definitive cancer screen: false positives occur with infections, autoimmune diseases, and other inflammatory states, and false negatives can occur in non‑secretory disease or very low‑level monoclonal production. Results must be interpreted alongside symptoms, imaging, and, when indicated, bone marrow biopsy and hematology consultation for a conclusive diagnosis and staging.

How often you should test immunoglobulin levels depends on the clinical context and risk: for low‑risk MGUS a common approach is a repeat at about 6 months after diagnosis and then annually if stable; for higher‑risk MGUS or smoldering myeloma monitoring is usually more frequent (often every 2–3 months during the first year, then every 3–6 months if unchanged); in active multiple myeloma testing is done much more often (commonly at each treatment cycle or monthly during therapy) and during remission is typically every 1–3 months initially before spacing out per your clinician’s plan.

Monitoring usually includes SPEP/IFE, quantitative IgG/IgA/IgM and serum free light chains and must be individualized by your hematologist based on risk factors, symptoms and other test results—report new symptoms (bone pain, recurrent infections, significant fatigue or weight loss) promptly so testing can be advanced if needed.

No — Immunoglobulin test results highlight patterns of imbalance or resilience—not medical diagnoses. Abnormal immunoglobulin levels or patterns can suggest immune activity or dysregulation and may prompt further evaluation, but they do not by themselves confirm cancer.

These results must be interpreted alongside symptoms, medical history, physical exam and other laboratory, imaging, or biomarker data by a qualified clinician; a definitive cancer diagnosis typically requires targeted testing such as imaging and tissue biopsy.

Immunoglobulin (Ig) abnormalities can reflect very different problems — low Ig levels may signal immune deficiency, whereas high or monoclonal Ig levels can be a marker of plasma‑cell disorders (e.g., monoclonal gammopathy or myeloma). “Improving” levels therefore depends on the cause: if testing shows a monoclonal spike or other findings suspicious for cancer you need prompt evaluation by a hematologist/oncologist for staging and disease‑directed treatment rather than measures to raise or lower Ig levels yourself.

If low Ig is the issue, management is driven by severity and clinical consequences: options include treating and preventing infections, optimizing nutrition and control of underlying disease, reviewing/reducing immunosuppressive drugs if appropriate, and — for significant or recurrent infections with proven hypogammaglobulinemia — immunoglobulin replacement therapy (intravenous or subcutaneous IG) and targeted vaccines or prophylactic antibiotics when recommended by a specialist. Follow up testing and specialist guidance are essential; do not start treatments or supplements on your own, and discuss the appropriate diagnostic workup and therapy with your clinician.