15. Fever

Question 1

thermoregulatory center in the hypothalamus, in charge of modifying heat production, integrates input from cold and warm thermal receptors located throughout body and generates output responses conserving body heat or increase its dissipation at the thermostatic set point, when body temperature begins to rise above the normal range, heat dissipating behaviors are initiated, when temperature falls below the normal range, heat production is increased, core temperature greater than 41 C or less than 34 C indicates bodies ability to thermoregulate is impaired

Answer 1

temperature regulation

Question 2

normal core temperature 36.0 -37.5 C, has diurnal variation nadir at 6:00 am and peak at 4:00-6:00pm, circadian rhythm and menstruation can vary temperature by 0.5-1C body temperature reflects the difference between heat production and heat loss, heavy exercise can elevated baseline temperature by 2-3 C, rectal temps are generally 0.6C 1F higher than oral

Answer 2

normal state

Question 3

core temperature of 38.0C, other sources define fever as two consecutive elevations of 38.3C or 101F, in neutropenic patients, fever is a single oral temperature of 38.3 (101.F) in the absence of an obvious environmental cause, or a temperature elevation of 38.0C 100.4F for 1 hour

Answer 3

fever definition

Question 4

hypothalamic thermostate dysfunction, related to central nervous system trauma, intracerebral bleeding, increased intracranial pressure, or drugs like anesthetics, usually resistant to antipyretic therapy and not associated with sweating

Answer 4

neurogenic fever

Question 5

infectious, non-infectious disorders, inflammatory immune mediated disorders, organ ischemia, neoplasms produce pyrogens from malignant cells, trauma, surgery

Answer 5

non-central fever

Question 6

produced by microorganisms through infections or toxins like c.diff or scromboid

Answer 6

exogenous pyrogens

Question 7

host cell derived, produced from cytokines Il-1, Il-6, interferon, TNF, also produced from immune complexes and complement

Answer 7

endogenous pyrogens

Question 8

acute febrile illness with a core temperature of 38C or higher without localizing signs of symptoms, history and physical examination cannot identify a specific source of fever, alternative terms are fever without localizing source or fever without a focus, examples include occult bacteremia, viral illness, or urinary tract infection, most common etiology is self-limited viral infection or occult bacterial infection, initial focus is always to rule out severe bacterial infections like bacteremia, meningitis, pneumonia, UTI, septic arthritis, and cellulitis, there are multiple other non-infectious etiologies, for children between 3-36 months of age, makes a significant number of pediatric emergency visits, ambulatory visits and ambulatory visits, 5-20% of febrile children have fever with no apparent source after adequate evaluation and examination

Answer 8

fever without localizing source

Question 9

infection is still most common but non-infectious is more frequent than that of children, same principle of focus on treatable occult infections like lung, urinary, abdomen, gallbladder, endocarditis, use of empirical antibiotics requires meticulous history and exam and combined with lab data, followed by risk benefit assessment

Answer 9

fever without localizing source in adult populations

Question 10

temperature of >/= 38.3C 101F for >3 weeks with an uncertain diagnosis after more than 3 clinic visits or 3 days of hospitalization, up to 50% of cases remain undiagnosed

Answer 10

fever of unknown origin

Question 11

abscess, endocarditis, tuberculosis, osteomyelitis, complicated urinary tract infection, epistein barr virus infection, CMV infection, HIV infection

Answer 11

infectious etiology of fever of unknown origin

Question 12

still’s disease, systemic lupus erythematosus, temporal arteritis, polymyalgia rheumatica, vasculitis

Answer 12

non-infectious inflammatory disease etiology of fever of unknown origin

Question 13

leukemia and lymphoma, renal cell carcinoma, colon cancer, central nervous, system, malignancies, hepatocellular carcinoma

Answer 13

fever of unknown origin

Question 14

subacute thyroiditis, drug fever, familial febrile syndromes, factitious fever

Answer 14

miscellaneous causes of fever of unknown origin

Question 15

abdominal abscesses, suphrenic, liver, splenic, diverticular, pelvic, mycobacterial, intraabdominal abscess, endocarditis, cytomegalovirus, epstein barr cirus, chikungunia virus, cryptococcus, babesia, erlichia, q fever, malaria, fungal infection, cholangitis, sinusitis, osteomyelitis, amebic hepatitis, prostate abscess

Answer 15

infectious etiologies of fever of unknown source

Question 16

Hodgkin’s disease, non-hodkin’s lymphoma leukemia, renal cell carcinoma, hepatoma

Answer 16

malignancies presenting as fever of unknown origin

Question 17

systemic lupus erythematosus, still’s disease, polymagia rheumatica, drug fever, hypersensitivity vasculitis, idiopathic vasculitis, polyarteritis nodosa, erythema multiforme, mixed connective tissue disease, serum sickness, rheumatic fever

Answer 17

hypersensitivity and autoimmune diseases presenting as fever of unknown orign

Question 18

comprehensive history and physical exam always needed, no evidence based algorithms exist to help guide the diagnostic workup, Sutton’s law, first consider the obvious, endless blood cultures are not indicated, trials of antibiotics generally not indicated except in neutropenic fever of unknown origin or sepsis

Answer 18

general principles

Question 19

observation of temperature pattern, pel ebstein fluctuating fever in hodgkin’s lymphoma, relapsing fever, drug fever, malaria, obtain historical aspects like fever preceding rash and others, physical examination, laboratory tests, noninvasive procedures, invasive procedures

Answer 19

classic fever of unknown origin

Question 20

flourodeoxyglucose positron emission tomography has been used to help detect infections or malignancies in patients with fever of unknown origin, multiple studies showing decrease in length of work up and diagnostic yield around 50%

Answer 20

role of FDG-PET scan