Coccidioides complement fixation: MedlinePlus Medical Encyclopedia

P Coccidioides complement fixation is a blood test that looks for antibodies to the fungus Coccidioides immitis. This fungus causes the disease coccidioidomycosis.

T How the Test is Performed
P A blood sample is needed.

T How to Prepare for the Test
P There is no special preparation for the test.

T How the Test will Feel
P When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging. Afterward, there may be some throbbing.

T Why the Test is Performed
P This test is used to detect infection with the fungus that causes coccidioidomycosis or valley fever. This condition can cause lung or widespread (disseminated) infection.

T Normal Results
P A normal result means no Coccidioides immitis antibodies are detected in the blood sample.
P Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

T What Abnormal Results Mean
P Abnormal results mean that Coccidioides immitis antibodies are present. This can mean that you have a current or recent infection.
P The test may be repeated after several weeks to detect a rise in titer (antibody concentration), which confirms an active infection.
P In general, the worse the infection, the higher is the titer, except in people with a weakened immune system.
P There can be false positive tests in people with other fungal diseases such as histoplasmosis and blastomycosis, and false negative tests in people with single lung masses from coccidioidomycosis.

T Risks
P Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
P Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)

T Alternative Names
P Coccidioides antibody test

T Images
- Blood test

T References
P Galgiani JN. Coccidioidomycosis (Coccidioides species). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 267.
P Iwen PC. Mycotic diseases. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 61.

T Review Date 9/10/2015
P Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

