Lecture 5 - Fever of Unknown Origin

Question 1

Fever

Answer 1

> 37.2 (98.9) in the morning and 37.7 (99.9( in the evening

Question 2

Normal body temperature range

Answer 2

35.6-38.2

elderly tend to have lower body temps

rectal 0.4 higher than oral
rectal 0.2 higher than core

Question 3

How is an individuals temperature determined?

Answer 3

hypothalamic set point

when this increases –> fever

• release of cytokines (IL-1, 6; TNF alpha)
• peripheral vasoconstriction
• increase in prostaglandin E2 (myalgia, arthralgia)

Question 4

What are the benefits of fever?

Answer 4

increased immunoglobulin synthesis 
T-cell activation 
increased cytokine production 
increased NK cell activity 
increased phagocytic cell activity 
suppression of microbial growth 
reduced virus replication

Question 5

Fever of unknown origin

Answer 5

fever >/= 38.3 (101F) and illness lasting 3 weeks and no known immunocompromised

failure to reach a diagnosis despite appropriate laboratory and radiologic investigation

Question 6

What are the most common causes of fever of unknown origin?

Answer 6

in the USA

infection - 33% (the MC infection is of the bugs that are already colonized in our bodies –shifts cause the infection)
neoplasia - 25%
connective tissue 13%

even though shifts in normal flora are the MC cause of fever of unknown origin, we must always rule out TB

Question 7

What is the treatment for TB?

Answer 7

Initial phase:
daily INH, rifampin, PZA and ethambutol x 8 weeks
may d/c ethambutol if sensitivities favorable

Continuation phase:
INH, rifampin either daily x 18 weeks or 2x/week x 18 weeks

Question 8

What is the TB prophylaxis for healthcare workers?

Answer 8

INH + B6