Health Encyclopedia

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 Values

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

Decreased levels of IgG may indicate the following:

Agammaglobulinemia (very rare)
Amyloidosis
Leukemia
Myeloma
Preeclampsia

Increased levels of IgM may indicate the following:

Early HIV infection
Infectious mononucleosis
Lymphoma
Macroglobulinemia
Myeloma
Rheumatoid arthritis

Decreased levels of IgM may indicate the following:

Agammaglobulinemia (very rare)
Amyloidosis
Leukemia
Myeloma

Increased levels of IgA may indicate the following:

Chronic infections, especially involving the gastrointestinal tract
Inflammatory bowel disease
Myeloma
Rheumatic fever

Decreased levels of IgA may indicate the following:

Agammaglobulinemia (very rare)
Hereditary IgA deficiency
Myeloma
Protein-losing gastroenteropathy

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:

Excessive bleeding
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

Special 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.

Review Date:6/14/2008
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.

ADAM Quality A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

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