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 looks specifically for the immunoglobulins IgM, IgG, and IgA.
How the Test is Performed
A blood sample is needed.
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. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
The test provides a rapid and accurate measurement of the amounts of the immunoglobulins IgM, IgG, and IgA.
IgG: 560 to 1800 mg/dL
IgM: 45 to 250 mg/dL
IgA: 100 to 400 mg/dL
The examples above show the common measurements for these test results. Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results. Some labs use different measurements or test different samples.
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 diagnose any of the conditions above. Often, slight abnormalities in the levels of immunoglobulins are clinically insignificant.
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 light-headed
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: Elsevier Saunders; 2011:chap 44.
McPherson RA, Massey HD. Laboratory evaluation of immunoglobulin function and humoral immunity. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 46.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.