Fever of unknown origin (FUO), as its name says, is a high temperature without any known cause after diagnostic tests have been done.
Three major causes are infections, tumors, and collagen vascular diseases. Collagen-vascular diseases include systemic lupus, rheumatoid arthritis, and scleroderma. They’re caused by the body’s immune (infection-fighting) system attacking its own organs.
Infections, the most common cause, include endocarditis (infection of the heart’s lining or valves), tuberculosis, abscesses, and viral infections such as cytomegalovirus infection. Tumors, the second most common cause, include Hodgkin’s and non- Hodgkin’s lymphomas. Other tumors are leukemia, multiple myeloma, and renal, liver, colon, and breast cancers. The most common collagen-vascular disease in young people is juvenile rheumatoid arthritis. In older people, it’s inflammation of the temporal artery, found at the temple region of the head.
Other rare causes of FUO are drugs such as antibiotics, antihistamines, antiseizure drugs, antiinflammatory drugs, and medicines used for acid reflux and peptic ulcers.
The medical definition describes the symptom: a temperature of 101° F (38.3° C) for more than 3 weeks and no diagnosis after 1 week of evaluation.
As part of the evaluation, the health care provider will take a detailed history, do a physical examination, and order blood tests.
If the diagnosis remains unclear, the health care provider may order imaging studies, such as x-rays and computed tomography (CT) of the chest, abdomen (belly), and pelvis.
If endocarditis may be the cause, echocardiography (an ultrasound test using sound waves to take pictures of the heart) will be done.
The disease causing the fever must be treated. A doctor who specializes in infections will help with diagnosis, evaluation, and treatment of infectious diseases. Antibiotics will be given for infections. If a tumor is found, an oncologist (a doctor specializing in cancer treatment) will be involved. For a collagenvascular disease, a rheumatologist (a doctor specializing in joint and collagen-vascular diseases) will help.
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Copyright © 2016 by Saunders, an imprint of Elsevier, Inc.
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