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Overview |
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Definition |
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By at least one definition, when a fever of more than 101°F (38.3°C) occurs
on several occasions over three weeks without identification of its cause
despite extensive investigation for at least a week, it becomes a fever of
unknown origin (FUO). There are other definitions specific to institutional
protocols, which include (a) 2 weeks of fever with either 3 days of inpatient
assessment or 3 outpatient visits, and (b) fever on at least 4 occasions over a
2 week period and 2 weeks of illness. Difficult-to-diagnose fevers have several
potential underlying causes, including infections, autoimmune diseases, and
undiscovered cancers. Between 5% and 15% of FUOs remain undiagnosed.
To determine the underlying cause of a FUO, take careful note of the
patient's history and symptoms. Recent travel to regions endemic for specific
infections provides clues, as does a history of drinking contaminated water. The
diagnostic path should include repeated physical examinations, laboratory
evaluations, noninvasive methods such as sonography, and invasive diagnostic
techniques such as biopsy.
The inability to diagnose FUO creates a dilemma regarding treatment.
Experimental evidence suggests that elevated temperatures benefit patients by
enhancing the body's defense mechanisms. However, clinical studies have not
conclusively supported that position.
Treat fevers in children susceptible to febrile seizures. Also provide
therapy to adults with cardiac or pulmonary conditions, as increases in body
temperature reduce oxygen consumption. |
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Etiology |
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Unknown by definition, but most probably due to infection, neoplasm, vascular
disease, or other endocrine, occupational, or environmental causes. Provider
must rely on patient's present and previous symptoms and diseases, current
medications, exposure to infections, recent travel, and other diagnostic clues.
Efforts to identify the cause of any fever start with the patient's medical
history and move on through physical examination, blood tests, noninvasive
diagnostic techniques, and invasive methods. |
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Risk Factors |
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- Recent travel, especially overseas
- Exposure to malaria, which can cause fever every second or third
day
- Exposure to certain fungi, such as coccidioidomycosis in the
southwestern United States and histoplasmosis in the Ohio River and Mississippi
River valleys
- Drinking contaminated water or consuming ice made from such water,
which may indicate typhoid fever
- Working in a meat-packing plant, which can harbor
brucellosis
- Use of medications that cause feverish adverse reactions
- Drug use or abuse
- AIDS
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Signs and Symptoms |
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- Fever of more than 101°F (38.3°C), either continuous or intermittent,
for at least two weeks
- Fever above 101°F whose identity remains unknown even after extensive
diagnostic testing
- Accompanying headache, myalgia, and general
malaise
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Differential
Diagnosis |
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There is a long list of potential causes, including the many forms of
infection, neoplasms, vascular disease, endocrine disorders, and environmental
or occupational insults. |
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Diagnosis |
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Physical Examination |
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Concentrate on the skin, eyes, nail beds, lymph nodes, heart, and abdomen to
obtain the best clues to the fever's origin. Repeat the examinations frequently
as the fever progresses undiagnosed. Take a thorough history. Inquire about
exposure to malaria. Determine whether the patient's workplace might harbor
infective agents. Check whether the patient has drunk contaminated water.
Consider the possibility that a medication has caused the
fever. |
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Laboratory Tests |
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CBC for anemia, leukopenia, lymphocytosis, thrombocytosis. Liver function
tests for obstructive diseases and inflammation. Blood cultures for aerobic or
anaerobic pathogens. Other body fluids and tissue for bacteria, mycobacteria,
and fungi. Urine analysis for infection or malignancy in urinary tract. Serology
for CMV, infectious mononucleosis, HIV, toxoplasmosis, and
chlamydia. |
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Pathology/Pathophysiology |
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Dependent on etiology |
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Imaging |
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Ultrasound can reveal the presence of cardiac vegetations, as well as
abnormalities in the pancreas, liver, and gallbladder. Computed tomography and
magnetic resonance imaging can help detect intra-abdominal abscesses,
abnormalities in the lymph nodes, and pathology of the spleen, liver, kidneys,
adrenals, pancreas, heart, mediastinum, or pelvis. Scanning with radionuclide
tracers (especially gallium) may identify localized areas of infection or
inflammation. |
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Other Diagnostic
Procedures |
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- Skin tests and sputum/urine cultures
- HIV antibody, thyroid, and rheumatoid factor tests
- Biopsy liver, bone marrow, or other suspected sites if other tests
have failed to produce a definitive
diagnosis.
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Treatment Options |
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Treatment Strategy |
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Debate surrounds the issue of whether or not to treat fever, particularly
when its source remains unknown. Advise rest, avoidance of rapid changes in
ambient temperature, and drinking large amounts of fluids. Prescribe
antipyretics for children who have suffered febrile seizures and adults with
heart or lung insufficiencies, who can be endangered by the excess demand for
oxygen brought on by the fever. Expect increased caloric and fluid demands.
Also, treat patients with organic brain syndrome; fever can cause changes in
their mental status. Wise treatment requires all possible efforts to identify
the fever's origin. |
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Drug Therapies |
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Use appropriate antipyretics where necessary to control the
fever:
- Acetaminophen
- Aspirin and other nonsteroidal anti-inflammatory drugs. Avoid
prescribing aspirin for children and teenagers, because it increases the risk of
Reye's syndrome.
If examination indicates the presence of infection, prescribe appropriate
agents based on patient history. A wide variety of anti-infective drugs exists,
tailored to specific types of infection. These include antibiotics, and
antimicrobial, antifungal, and antiviral agents. Note that the drugs have less
effect in patients with severely impaired immune systems. A steroid trial may be
considered, although consider detrimental effects with certain undiagnosed
conditions. |
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Complementary and Alternative
Therapies |
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General immune support with nutrition and herbs may alleviate fevers of
unknown origin. Homeopathic remedies may provide relief. |
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Nutrition |
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- Eliminate alcohol, caffeine, refined foods, and sugar which have an
immunosuppressive effect.
- Water and/or electrolyte replacement drinks should be increased to
prevent dehydration.
- Vitamin C (250 to 1,000 mg bid to tid), beta-carotene (15,000 to
50,000 IU/day), and zinc (10 to 30 mg/day) enhance immunity and reduce
inflammation.
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Herbs |
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Herbs are generally a safe way to strengthen and tone the body's systems. As
with any therapy, it is important to ascertain a diagnosis before pursuing
treatment. Herbs may be used as dried extracts (capsules, powders, teas),
glycerites (glycerine extracts), or tinctures (alcohol extracts). Unless
otherwise indicated, teas should be made with 1 tsp. herb per cup of hot water.
Steep covered 5 to 10 minutes for leaf or flowers, and 10 to 20 minutes for
roots. Drink 2 to 4 cups/day. Tinctures may be used singly or in combination as
noted.
The following antipyretic herbs and immune supportive herbs may be helpful in
reducing fever and improving immunity: coneflower (Echinacea purpurea),
yarrow (Achillea millefolium), white willow bark (Salix alba),
lemon balm (Melissa officinalis), spearmint (Mentha spicata),
catnip (Nepeta cateria), and elder (Sambucus nigra). Combine 1
part of coneflower and 1 part white willow bark with equal parts of 2 or more
herbs. Drink 3 to 4 cups/day, 2 to 4 ounces tid to qid for
children. |
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Homeopathy |
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An experienced homeopath should assess individual constitutional types and
severity of disease to select the correct remedy and potency. For acute
prescribing use 3 to 5 pellets of a 12X to 30C remedy every one to four hours
until acute symptoms resolve.
- Aconite when fever comes on suddenly and alternates with
chills, heat, and flushing of the face. There is thirst for cold drinks, with
anxiety.
- Apis mellifica for fever with alternating sweats and dry
heat.
- Belladonna for sudden onset of high fever with hot, red face,
glassy eyes, thirstlessness, and hot body with cold hands.
- Bryonia for fever with marked aggravation from the slightest
movement.
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Acupuncture |
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Acupuncture may be helpful in supporting immune
function. |
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Patient Monitoring |
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Continue to examine patient and take blood for culturing until the cause of
the fever becomes evident. A thoughtful, individualized approach to the patient
eventually identifies the cause in most cases. |
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Other
Considerations |
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Prevention |
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Caution with international travel and exposure to obvious contaminants will
reduce likelihood of acquiring certain causative pathogens. |
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Complications/Sequelae |
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Dependent on etiology. Before any surgeries, patient should inform staff of
history of fever of unknown origin. |
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Prognosis |
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Dependent on etiology, patient age, and other compromise |
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Pregnancy |
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Left untreated, fever can be dangerous to the fetus. Nutritional, herbal, and
homeopathic support for fevers are generally safe in pregnancy, yet use with
caution. |
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References |
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Bartram T. Encyclopedia of Herbal Medicine. Dorset, England: Grace
Publishers; 1995:182.
Berkow R. Merck Manual, Home Edition. Rahway, NJ: The Merck Publishing
Group; 1997.
Berkow R, Beers MH. The Merck Manual of Diagnosis and Therapy. Rahway,
NJ: The Merck Publishing Group; 1992.
Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic
Guide to Herbal Medicine. Boston, Mass: Integrative Medicine Communications;
1998:427.
Duke JA. The Green Pharmacy. Emmaus, Pa: Rodale Press,
1997.
Morrison R. Desktop Guide to Keynotes and Confirmatory Symptoms.
Albany, Calif: Hahnemann Clinic Publishing; 1993:6, 58, 62.
Walker LP, Hodgson E. The Alternative Pharmacy. Paramus, NJ: Prentice
Hall Press; 1996. |
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Copyright © 2000 Integrative Medicine
Communications This publication contains
information relating to general principles
of medical care that should not in any event be construed as specific
instructions for individual patients. The publisher does not accept any
responsibility for the accuracy of the information or the consequences arising
from the application, use, or misuse of any of the information contained herein,
including any injury and/or damage to any person or property as a matter of
product liability, negligence, or otherwise. No warranty, expressed or implied,
is made in regard to the contents of this material. No claims or endorsements
are made for any drugs or compounds currently marketed or in investigative use.
The reader is advised to check product information (including package inserts)
for changes and new information regarding dosage, precautions, warnings,
interactions, and contraindications before administering any drug, herb, or
supplement discussed herein. | |