FUO Flashcards
INTRODUCTION
_____________________)refers to a condition in which the patient has an elevated temperature but despite investigations by a physician no explanation has been found..
If the cause is found it is usually a diagnosis of exclusion, that is, by eliminating all possibilities until only one explanation remains, and taking this as the correct one.
Fever of unknown origin (FUO), pyrexia of unknown origin (PUO)or febris e causa ignota (febris E.C.I.
MECHANISMS OF HYPERTHERMIA AND ASSOCIATED CONDITIONS
1.Excessive heat production
2.Disorders of heat dissipation
3.Disorders of hypothalamic function
Excessive heat production:
exertional hyperthermia,
thyrotoxicosis,
pheochromocytoma,
cocaine,
delerium tremens,
malignant hyperthermia
Disorders of heat dissipation:
heat stroke,
autonomic dysfunction
Disorders of hypothalamic function:
neuroleptic malignant syndrome,
CVA,
trauma
NORMAL BODY TEMPERATURE
For healthy individuals 18 to 40 years of age, the mean oral temperature is
36.8°±0.4°C (98.2°±0.7°F)
NORMALBODYTEMPERATURE
Low levels occur at________ and higher levels at _________
6 A.M.
4 to 6 P.M.
The maximum normal oral temperature is_________ at 6 A.M. and ____________ at 4 P.M.
- 2°C (98.9°F)
- 7°C (99.9°F)
____________-: resetting of the thermostatic set-point in the anterior hypothalamus and the resultant initiation of heat-conserving mechanisms until the internal temperature reaches the new level.
Fever
________: an elevation in body temperature that occurs in the absence of resetting of the hypothalamic thermoregulatory center
Hyperthermia
In 1961 Petersdorf and Beeson suggested the following criteria:
Fever higher than 38.3°C (101°F) on several occasions
Persisting without diagnosis for at least 3 weeks
At least 1 week’s investigation in hospital
What is the new definition for FUO?
A new definition which includes the outpatient setting (which reflects current medical practice) is broader, stipulating:
3 outpatient visits or
3 days in the hospital without elucidation of a cause or
1 week of “intelligent and invasive” ambulatory investigation.
CLASSES OF FUO
- classic
- Nosocomial
- Immune-defiicient
4.
This refers to the original classification by Petersdorf and Beeson. Studies show there are **five categories of conditions: **
Classic FUO
Five categories of classic FUO
This refers to the original classification by Petersdorf and Beeson. Studies show there are five categories of conditions:
- Infections (e.g. abscesses, endocarditis, tuberculosis, and complicated urinary tract infections,)
- Neoplasms( e.g. lymphomas leukemia’s),
- Connective tissue diseases (e.g. temporal arteritis and polymyalgia rheumatica, systemic lupus erythematosus and rheumatoid arthritis),
- Miscellaneous disorders (e.g. alcoholic hepatitis, granulomatous conditions), and
- Undiagnosed conditions
CLASSES OF FUO
______________ refers to pyrexia in patients that have been admitted to hospital for at least 24 hours.
This is commonly related to hospital associated factors such as, surgery, use of urinary catheter intravascular devices (i.e. “drip”, pulmonary artery catheter), drugs (antibiotics induced Clostridium difficile colitis, and drug fever), immobilization (decubitus ulcers)
Nosocomial FUO
CLASSES OF FUO
can be seen in patients receiving chemotherapy or in hematologic malignancies.
Fever is concomitant with neutropenia (neutrophil <500/uL) or impaired cell-mediated immunity.
The lack of immune response masks a potentially dangerous course. Infection is the most common cause.
Immune-deficient
CLASSES OF FUO
_______________ are a subgroup of the immunodeficient FUO, and frequently have fever. The primary phase shows fever since it has a mononucleosis like illness. In advanced stages of infection fever mostly is the result of a superimposed infections.
HIV-infected patients
SOME IMPORTANT CAUSES
______________ is the most frequent cause of FUO.
Extrapulmonary tuberculosis
_____________, as sole symptom of an adverse reaction to medication, should always be considered.
Drug-induced hyperthermia
Disseminated granulomatoses such as Tuberculosis, Histoplasmosis, Coccidioidomycosis, Blastomycosis and Sarcoidosis are associated with FUO.
________________ are the most common cause of FUO in adults.
Lymphomas
__________ although uncommon, is another important etiology to consider.
Endocarditis,
BACTERIALPYROGENS
- Lipopolysaccharide (LPS) endotoxin
- Staphylococcus aureusenterotoxins
- Staphylococcus aureustoxic shock syndrome toxin (TSST)
- Group A and B streptococcal toxins
Endotoxin binds to LPS-binding protein and is transferred to CD14 on macrophages, which stimulates the release of TNFα.
Lipopolysaccharide (LPS) endotoxin
Both Staphylococcustoxins are superantigens and activate T cells leading to the release of interleukin (IL)-1, IL-2, TNFαand TNFβ, and interferon (IFN)-gamma in large amounts
Staphylococcus aureusenterotoxins
Staphylococcus aureustoxic shock syndrome toxin (TSST)
_______________
Exotoxins induce human mononuclear cells to synthesize not only TNFαbut also IL1 and IL-6
Group A and B streptococcal toxins
MINIMALINITIALDIAGNOSTICWORKUPFORFUO
Comprehensive history
Physical examination
CBC + differential
Blood film reviewed by hematopathologist
Routine blood chemistry
UA and microscopy
Blood (x 3) and urine cultures
Mourad,
MINIMAL INITIAL DIAGNOSTIC WORK UP FOR FUO
Comprehensive history
Antinuclear antibodies, rheumatoid factor
HIV antibody
CMV IgM antibodies; heterophile antibody test (if c/w mono-like syndrome)
Q-fever serology (if risk factors)
Chest radiography
Hepatitis serology (if abnormal LFTs)
Mourad, et al. Arch Intern
Diagnostic yield of liver biopsy has ranged from_______
Note : Physical exam finding of hepatomegaly or abnormal liver profile are not helpful in predicting abnormal biopsy result.
Complication rate is 0.06% to 0.32%
14% to 17%.
The diagnostic yield of bone marrow cultures in immunocompetent individuals has been found to be))))))))
0% to 2%
