History. It
is in the diagnosis of a febrile illness that the science and art of medicine
come together. In no other clinical situation is a meticulous history more
important. Painstaking attention must be paid to the chronology of symptoms in
relation to the use of prescription drugs (including drugs, supplements, or
herbs taken without a physician’s supervision) or treatments such as surgical
or dental procedures. The exact nature of any prosthetic materials and/or
implanted devices should be ascertained. A careful occupational history should
include exposures to animals; toxic fumes; potential infectious agents;
possible antigens; or other febrile or infected individuals in the home,
workplace, or school. A history of the geographic areas in which the patient
has lived and a travel history should include locations during military service.
Information on unusual hobbies, dietary proclivities (such as raw or poorly
cooked meat, raw fish, and unpasteurized milk or cheeses), and household pets
should be elicited, as should that on sexual orientation and practices,
including precautions taken or omitted. Attention should be directed to the use
of tobacco, marijuana, intravenous drugs, or alcohol; trauma; animal bites;
tick or other insect bites; and prior transfusions, immunizations, drug
allergies, or hypersensitivities. A careful family history should include information
on family members with tuberculosis, other febrile or infectious diseases,
arthritis or collagen vascular disease, or unusual familial symptomatology such
as deafness, urticaria, fevers and polyserositis, bone pain, or anemia. Ethnic
origin may be critical. For example, blacks are more likely than persons in
other groups to have hemoglobinopathies. Turks, Arabs, Armenians, and Sephardic
Jews are especially likely to have familial Mediterranean fever.
Physical Examination. A meticulous physical examination should be repeated on a
regular basis. All the vital signs are relevant. The temperature may be taken
orally or rectally, but the site used should be consistent. Axillary
temperatures are notoriously unreliable. Special attention should be paid to
the skin, lymph nodes, eyes, nail beds, cardiovascular system, chest, abdomen,
musculoskeletal system, and nervous system. Rectal examination is imperative.
The penis, prostate, scrotum, and testes should be examined carefully and the
foreskin, if present, retracted. Pelvic examination must be part of every
complete physical examination of a woman, with a search for such causes of
fever as pelvic inflammatory disease and tubo-ovarian abscess.
Laboratory Tests. Few signs and symptoms in medicine have as many diagnostic
possibilities as fever. If the history, epidemiologic situation, or physical
examination suggests more than a simple viral illness or streptococcal
pharyngitis, then laboratory testing is indicated. The tempo and complexity of
the workup will depend on the pace of the illness, diagnostic considerations,
and the immune status of the host. If findings are focal or if the history,
epidemiologic setting, or physical examination suggests certain diagnoses, the
laboratory examination can be focused. If fever is undifferentiated, the
diagnostic nets must be cast farther, and certain guidelines are indicated, as
follows.
Clinical Pathology. The workup should include a complete
blood count; a differential count should be performed manually or with an
instrument sensitive to the identification of eosinophils, juvenile or band
forms, toxic granulations, and Döhle bodies, the last three of which are
suggestive of bacterial infection. Neutropenia may be present with some viral
infections, particularly parvovirus B19 infection; drug reactions; systemic
lupus erythematosus; typhoid; brucellosis; and infiltrative diseases of the
bone marrow, including lymphoma, leukemia, tuberculosis, and histoplasmosis.
Lymphocytosis may occur with typhoid, brucellosis, tuberculosis, and viral disease.
Atypical lymphocytes are documented in many viral diseases, including infection
with Epstein-Barr virus, cytomegalovirus, or HIV; dengue; rubella; varicella;
measles; and viral hepatitis. This abnormality also occurs in serum sickness
and toxoplasmosis. Monocytosis is a feature of typhoid, tuberculosis,
brucellosis, and lymphoma. Eosinophilia may be associated with hypersensitivity
drug reactions, Hodgkin’s disease, adrenal insufficiency, and certain metazoan
infections. If the febrile illness appears to be severe or is prolonged, the
smear should be examined carefully for malarial or babesial pathogens (where
appropriate) as well as for classic morphologic features, and the erythrocyte
sedimentation rate should be determined. Urinalysis, with examination of
urinary sediment, is indicated. It is axiomatic that any abnormal fluid
accumulation (pleural, peritoneal, joint), even if previously sampled, merits
reexamination in the presence of undiagnosed fever. Joint fluids should be
examined for bacteria as well as crystals. Bone marrow biopsy (not simple
aspiration) for histopathologic studies (as well as culture) is indicated when
marrow infiltration by pathogens or tumor cells is possible. Stool should be
inspected for occult blood; an inspection for fecal leukocytes, ova, or
parasites also may be indicated.
Chemistry.
Electrolyte, glucose,
blood urea nitrogen, and creatinine levels should be measured. Liver function
tests are usually indicated if efforts to identify the cause of fever do not
point to the involvement of another organ. Additional assessments (e.g.,
measurement of creatinine phosphokinase or amylase) can be added as the workup
progresses.
Microbiology. Smears and cultures of specimens from the throat, urethra,
anus, cervix, and vagina should be assessed when there are no localizing
findings or when findings suggest the involvement of the pelvis or the
gastrointestinal tract. If respiratory tract infection is suspected, sputum
evaluation (Gram’s staining, staining for acidfast bacilli, culture) is
indicated. Cultures of blood, abnormal fluid collections, and urine are
indicated when fever is thought to reflect more than uncomplicated viral
illness. Cerebrospinal fluid should be examined and cultured if meningismus,
severe headache, or a change in mental status is noted.
Radiology.
A chest x-ray is usually
part of the evaluation for any significant febrile illness.
Outcome of Diagnostic Efforts In most cases of fever, either the patient recovers
spontaneously or the history, physical examination, and initial screening
laboratory studies lead to a diagnosis. When fever continues for 2 to 3 weeks,
during which time repeat physical examinations and laboratory tests are
unrevealing, the patient is provisionally diagnosed as having fever of unknown
origin
Source:
Harrison_s_Principles_of_Internal_Medicine_16th_Edition
No comments:
Post a Comment