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Quantitative immunoglobulins - nephelometry
Definition
Quantitative nephelometry is a test to quickly and accurately measure the specific level of certain proteins called immunoglobulins in your blood. Specifically, it looks for the proteins IgM, IgG, and IgA.
How the Test is Performed
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
How to Prepare for the Test
You may be asked not to eat or drink anything for 4 hours before the test.
How the Test Will Feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the Test is Performed
The test provides a rapid and accurate measurement of the amounts of the immunoglobulins M, G, and A. Immunoglobulins are proteins that are mostly antibodies.
Normal Results
- IgG: 560 to 1800 mg/dL
- IgM: 45 to 250 mg/dL
- IgA: 100 to 400 mg/dL
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Increased levels of IgG may indicate the following:
- Chronic infection or inflammation
- Hyperimmunization
- IgG multiple myeloma
- Liver disease
- Rheumatic fever
- Rheumatoid arthritis
- Agammaglobulinemia (very rare)
- Amyloidosis
- Leukemia
- Myeloma
- Preeclampsia
- Early HIV infection
- Infectious mononucleosis
- Lymphoma
- Macroglobulinemia
- Myeloma
- Rheumatoid arthritis
- Agammaglobulinemia (very rare)
- Amyloidosis
- Leukemia
- Myeloma
- Chronic infections, especially involving the gastrointestinal tract
- Inflammatory bowel disease
- Myeloma
- Rheumatic fever
- Agammaglobulinemia (very rare)
- Hereditary IgA deficiency
- Myeloma
- Protein-losing gastroenteropathy
Risks
There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Considerations
Nephelometry determines the total amount of each immunoglobulin but cannot distinguish antibodies. Other tests such as immunoelectrophoresis or immunofixation can be used to make these distinctions.
References
McPherson RA and Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: WB Saunders; 2007:40-1.
Adkinson Jr. NF, Yunginger JW, Busse WW, et al.eds. Middleton's Allergy: Principles and Practice. 6th ed. Philadelphia, Pa: Mosby; 2003:615-16.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and James R. Mason, MD, Oncologist, Director, Blood and Marrow Transplantation Program and Stem Cell Processing Lab, Scripps Clinic, Torrey Pines, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
