Approach to Fever Flashcards
What is a normal temperature?
98.2 + or - 0.7
What is the daily variation that occurs with fever?
Nadir at 0600, and peak at 1700
How much higher is rectal temp compared to oral?
Usually 1 degree F higher
What is the effect of menstruation on body temp?
Increases by a degree C
What is the definition of a fever?
Two consecutive elevations of 101 F, unless neutropenic (then just one)
What is the thermoregulatory center of the body?
Hypothalamus
What is the cooling center of the body?
Anterior hypothalamus
What is the heating center of the body?
Posterior hypothalamus
Where are our thermoreceptors?
Skin and muscles
What is the definition of hyperthermia?
Increased body temp above that set by the central regulation due to insufficient heat dissipation
What are the two main exogenous sources of pyrogens?
Toxins
Microorganisms
What are the major cytokines that mediate fever?
IL-1, IL-6, IFN, TNF
What is the definition of a fever of unknown origin (FUO)?
Fever greater than 38.3 for 2 or 3 weeks without identifiable etiology
What is a fever without localizing source?
Fever without ssx or a localizing source
What is the most common cause of fever without a localizing source?
Infectious etiology
What is the most common cause of fever without a source in 3-36 mo?
Occult bacteremia w/o ssx of sepsis
What are the predictors of occult bacteremia?
- Fever
- WBC more than 15K
What is NOT predictive of occult bacteremia?
Response to antipyretics
Clinical appearance
What percent of kids with a fever w/o source and a white count of greater than 30k have occult bacteremia?
42.3%
True or false: vaccines can mask ssx
True
What is the Yale observational scale?
Assessment to quantify toxic appearance, with higher score meaning more toxic
What is the most common cause of osteomyelitis in sickle cell patients?
Salmonella
What is the sensitivity and specificity of a WBC count greater than 15k for sepsis?
80% sensitive and specific
True or false: patient with Neisseria meningitides always have leukocytosis?
False– may have leukopenia
When are blood cultures particularly warranted?
If WBC more than 15k
When are urine cultures necessary?
If there is an abnormal UA
What are the labs that are helpful in the diagnosis of sepsis in infants?
CRP
Procalcitonin
What diseases can result in aberrant CRP and procalcitonin levels?
Renal disease
What are the four bacteria that should be suspected of causing sepsis?
S. pneumo
S. Aureus
Neisseria
Hemophilus
What is the abx of choice for sepsis?
Ceftriaxone
What is the most common cause of a fever without a source in adults? How is this different than in children?
Infections still most common as in adults, but non-infectious causes increase
What are the four organ systems that should be suspected of causing bacteremia?
Lung
Urinary
Abdomen
Endocarditis
What are the four categories of FUOs?
Nosocomial
Neutropenic
HIV-associated
Classic
What specific patient population needed to be treated for sepsis urgently?
HIV associated or immunocompromised
What is the most common nosocomial sepsis?
Pneumonia
UTIs
What are the inflammatory causes of sepsis?
Aspiration
Phlebitis
Arthritis
What percent of nosocomial fevers are caused by malignancy?
10%
What percent of fevers are caused by ischemia (MI, stroke, PE etc)?
6%
What percent of nosocomial fevers are caused by drugs?
10%
How can you diagnose fevers caused by drugs?
Monitor fevers spikes and if they occur with drug administration
What percent of FUOs are: infectious?
30%
What percent of FUOs are: malignancy?
30%
What percent of FUOs are: inflammatory/autoimmune?
10%
What percent of FUOs are: undiagnosed?
10%
What is the most common infectious cause of FUO?
Abdominal abscesses
What should be infectious cause of FUO should be suspected in DM pts?
Osteomyelitis
What are the two most common malignancies that cause fevers?
Hodgkin’s disease
Non-Hodgkin’s
Leukemia
What causes fever of malignancy?
Release of cytokines
What is Still’s disease?
a rare systemic inflammatory disease characterized by the classic triad of persistent high spiking fevers, joint pain and a distinctive salmon-colored bumpy rash
Unknown cause
What are the autoimmune diseases that can cause FUOs?
SLE
Still’s disease
Polymyalgia rheumatic
What are the three most common autoimmune causes of FUOs?
- Granulomatous hepatitis
- Crohn’s
- Sarcoidosis
What is Sutton’s law?
First, consider the obvious
What is the classic cause of IL-12 resistance?
BCG vaccine
What is temporal arteritis?
Vasculitis of the branches of the external carotid artery, which may affect the ophthalmic artery