Quantitative nephelometry is a test to quickly and accurately measure the specific level of certain proteins called immunoglobulins in your blood. Immunoglobulins are antibodies that help your body fight infection.
This test specifically looks for the proteins IgM, IgG, and IgA.
How the test is performed
A blood sample is needed. For information on how this is done, see: Venipuncture
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.
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.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
Chronic infections, especially involving the gastrointestinal tract
Inflammatory bowel disease
Decreased levels of IgA may be due to:
Agammaglobulinemia (very rare)
Hereditary IgA deficiency
It is important to note that other testing is required to confirm or make a diagnosis of any of the conditions above. Often, slight abnormalities in the levels of immunoglobulins are clinically insignificant.
What the risks are
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:
Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
Nephelometry determines the total amount of each immunoglobulin but cannot distinguish specific antibodies. Other tests such as immunoelectrophoresis or immunofixation can be used to make these distinctions.
Ashihara Y, Kasahara Y, Nakamura RM. Immunoassays and immunochemistry. In McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 44.
McPherson RA, Massey HD. Laboratory evaluation ofimmunoglobulin function and humoral immunity. In McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia,Pa: Saunders Elsevier; 2011:chap 46.
Perry MC. Plasma cell disorders. In Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap193.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.