Fever Flashcards
Systematic, non-specific defensive response secondary to infection or tissue damage indicated by high body temperature (38.3C or greater)
Fever
What is responsible for Body Temp Regulation?
Hypothalamus
Specifically the Anterior Hypothalamus, which receives information from Central and Peripheral Thermoceptors in the body.
What is the Normal Temperatures for:
- Oral
- Rectal
- Axillary
- Tympanic
- Oral = 35.8 - 37.3C (96.4 - 99.1F)
- Rectal = 36.1 - 37.4C (97.6 - 99.3F)
- Axillary = 36.5 - 37.4C (97.5 - 99.3F)
- Tympanic = 35.8 - 37.5C (96.4 - 99.5F)
T/F: Fevers are usually highest in the morning.
False!
Fevers are usually higher in the evening, so you want to monitor temperature throughout the day.
Afebrile temps in the morning doesn’t mean the pt is afebrile.
Main causes of Fever
- Infections (20-40%)
- Neoplasms (7-20%)
- Collagen Vascular Dz (15-25%)
- Miscellaneous Dz
- Fever of Unknown Origin (FUO)
T/F: Literature suggests that between 5 and 15% of FUO cases defy the diagnosis.
True
Endogenous Mechanism of Fever:
- Interleukin-1 (IL-1) released by the macrophage
- Tumor Necrosis Factor released from cells (macrophages, mast cells, or endothelial cells)
Exogenous Mechanism of Fever:
- Phagocytosis destruction of bacteria and release of the endotoxin LPS (Lipopolysaccharide)
Beneficial Effects of Fever
- Helps set up specific defense (production of T-Cells)
- Speeds up metabolism for tissue repair
- Increases the antiviral effect of interferons
T/F: Healthy individuals can tolerate temperatures up to 110F (43.33C) without ill effects.
False, 105F (40.5C)
Consequences of Fever
- Children can get convulsions
- Elderly can get Myocardial Failure, Ischemia, or Shock
- Immunocompromise
At what temperature is someone dx with EXTREME hyperthermia?
108F (42.22C)
What can Extreme Hyperthermia cause?
- Endothelial Vascular Damage
- Disseminated Intravascular Coagulation (DIC)
- Metabolic Derangements
- Hypoxia
- Seizures/Coma
Things to think about when someone presents with a Fever:
- Host Factors (Vulnerable? Toxic?)
- What could cause this?
- Symptoms?
- Pattern of Fever
- Drug use?
- Hypersensitive?
Sign/Symptoms
- Sometimes asymptomatic
- Warmth/Flushing
- Malaise/Myalgia
- Fatigue
- Chill/Rigor
- Stupor/Lethargy
- Convulsions
- Tachycardia
When should you treat a fever immediately?
- Children because of their tendency for febrile convulsions
- Patient has a serious primary dz like heart, lung, or kidney dz
T/F: When treating a fever, the goal of therapy is to reduce body temperature back to “normothermia.”
False! That does not need to be the goal!
Goal: Reduced to the extent that subjective symptoms improve but the beneficial effects remain.
If patient is hyperpyrexic or hyperthermic, what would your treatment be?
- Physical Cooling
- Salicylates or Acetominophen
In practice, once you have treated a patient for fever, what are you wanting to see to fulfill the goal of therapy?
Temp decrease by 1-1.5C around 1-2 hours after drug administration
Fever without any clear focal symptoms or focal findings could indicate what?
Septicemia of pneumococcal or other etiology.
What should we do if an baby less than 3 months old presents with a fever?
- Fever can cause serious fulminant dz, so don’t leave this alone
- Observe the child’s neurological symptoms and alertness (Think Meningitis)
- Hospital-level investigation is usually necessary!!! (But if treating outpt, make sure the parents can contact the doctor immediately in case of emergency)
What is the most common cause of fever and how would this present?
Viral
Presentation:
- Runny Nose
- Sore Throat
- Cough
- Hoarseness
- Myalgia
Sometimes:
- Diarrhea
- Nausea
- Vomiting
Presentation of Fever of Bacterial Origin in the CNS:
- Headache
- Neck Stiffness
- Confusion
Presentation of Fever of Bacterial Origin in the LRI:
- Coughing
- Difficulty Breathing
- Thick Mucus Production
- Chest Pain (sometimes)
Presentation of Fever of Bacterial Origin in the URI:
- Runny Nose
- Headache
- Cough
- Sore Throat
Presentation of Fever of Bacterial Origin in the GU:
- Burning
- Frequency
- Suprapubic Pain
- Back Pain
Presentation of Fever of Bacterial Origin in the GI:
- Diarrhea
- Nausea
- Vomiting
- Hematochezia
Presentation of Fever of Bacterial Origin in the Skin:
- Redness
- Swelling
- Warmth
- Pus
- Pain occurs at site of infection
QUICK, What should you think!
Fever with Rash
Meningococcal Septicemia
QUICK, What should you think!
Fever with Stomach Pain and Vomiting
- Appendicitis
- UTI
QUICK, What should you think!
Fever with Neck Pain
CNS Infection
QUICK, What should you think!
Fever with Joint Pain
- Purulent Joint Infection
- Rheumatic Fever
- Gonorrhea in young, sexually active individuals
How do you define a FUO (Fever of Unknown Origin)
- Illness of more than 3 week duration
- Fever higher than 38.3C (100.94F) on several occasions
- Dx uncertain after 1 week of study in the hospital
What are the “Big Three” of FUO?
- Infections (40%)
- Neoplasms (15%)
- Collagen Vascular Dz (20%)
Possible causes of a bacterial abscess:
- Hx of Surgery
- Hx of Trauma
- Hx of Endoscopy
- Hx of Gynecological Procedure
- Hx of Diverticulosis
Common locations of bacterial abscesses:
- Subphrenic Space
- Liver
- RLQ
- LLQ
- Retroperitoneal Space
- Female Pelvis (tubo-ovarian abscess in PID)
Cause of Fever that is usually due to an atypical mycobacteria in the kidneys or mesenteric lymph nodes with disseminated visceral infections. A CXR may be normal.
Bacterial TB
*PPD tests could be negative too because positive may not happen until 4-6 weeks after infection
Features of Bacterial Endocarditis (aside from fever :P)
- New Murmur
- Leukocytosis
- Embolic Events
- Blood Cultures (3 sets from 2 different sites)
What is the most common reason for negative blood cultures in bacterial endocarditis cases?
(5-10% of endocarditis cases have this result)
Prior Antibiotic Therapy
Cause of fever assc with pain in URQ or back, nausea, vomiting, jaundice, and/or palpable gallbladder.
Bacterial Hepatobiliary Infections
- Cholangitis
- Cholecystitis
- Gallbladder Empyema
Labs for a Bacterial Hepatobiliary Infection would show?
- Elevated LFTs
What does Bacterial Osteomyelitis cause?
Localized Pain or Discomfort
T/F: The most common reason for misdiagnosis of osteomyelitis is the failure to consider the dz in a patient who is febrile with MSK symptoms.
True
Best Imaging Technique for Osteomyelitis Investigation?
MRI
This cause of fever can manifest as FUO and if systemic can be caused by the onset of juvenile rheumatoid arthritis. Labs would show leukocytosis, elevated ESR, anemia, abnormal LFTs.
Collagen Vascular and Autoimmune Dzs
- Polyarteritis Nodusa
- Rheumatoid Arthritis
- Mixed CT Dz
- Granulomatous Dz
- Inherited Dz
Presentation of the following Granulomatous Dz:
Sarcoidosis
- Multiorgan Involvement
- Rarely had fever and malaise without lymph node or pulmonary involvement
- Erythemia Nodosum occ. present
Presentation of the following Granulomatous Dz:
Crohn’s Dz
- Diarrhea
- Other Abdominal Symptoms are usually absent (esp in young adults)
Presentation of the following Granulomatous Dz:
Granulomatous Hepatitis
- Fever
- Hepatomegaly
- Asthenia
- Sometimes Arthralgias
- Sometimes Myalgias
Labs for Granulomatous Dz:
- Elevated Alkaline Phosphate Level (most consistently seen)
***Elevated serum ACE in Sarcodosis
Presentation of the following Inherited Dz:
Mediterranean Descent Fever
Recurrent febrile episodes at varying intervals assc with pleural, abdominal, or joint pain due to polyserositis.
How do you dx Mediterranean Descent Fever?
- Family History
- Dx: Genetic Testing
What neoplasms can cause Fever?
- Lymphomas
- Leukemias
- Solid Tumors (commonly renal cell carcinoma)
- Malignant Histiocytosis
This is a rare rapidly progressive malignant dz that manifests as high fevers, weight loss, enlarged lymph nodes, and hepatosplenomegaly.
Malignant Histiocytosis
What drugs can cause fever?
- Beta-lactam abx
- Procainamide
- Isoniazide
- Alpha-methyldopa
- Quinidine
- Phenytoin
What do you do if you think a drug has caused the fever?
- Discontinue the suspected drug
- Within 72 hours, defervescence should occur.
If not, it is probably not a drug related cause.
Endocrine Causes of Fever
- Hyperthyroidism
- Subacute Thyroiditis
- Adrenal Insufficiency
Presentation of an Endocrine Cause of Fever
- Tender Thyroid
- Exopthalomos
- Tachycardia
- Frequent Bowel Movements
- Increased Sweating
- Heat Intolerance
Labs: TSH! and CBC
Situational Fevers can be caused by?
- Travel
- Animal
- Occupational
- Viral Contraction
When a pt reports recently traveling to a tropical place and comes back with a fever, what are we thinking is the cause?
- Malaria
- Rickettsial
- Dengue Fever
- Schistomsomiasis
When a pt reports recently traveling to a cosmopolitan place and comes back with a fever, what are we thinking is the cause?
- Giardia
- Lyme Dz
- Rocky Mountain Spotted Fever
- Amebic Dysentery
When a pt reports having a cat and gets a fever, what are we thinking is the cause?
- Pasteurella multocida
- Tocoplasmosis
When a pt reports having a turtle and gets a fever, what are we thinking is the cause?
Salmonellosis
When a pt reports contact with an animal and gets a fever, what are we thinking is the cause?
RABIES
When a pt reports working in a slaughterhouse and gets a fever, what are we thinking is the cause?
Let’s blame the slaughterhouse.
When a pt reports working in leather production and gets a fever, what are we thinking is the cause?
ANTHRAX IN THIS BIHHH
Viral causes of Fever?
- HIV
- Hep A
- Hep B
- Hep C
Indications for types of Physical Exam if pt has an acute/symptomatic fever?
Focused Exam
Indications for types of Physical Exam if pt has a persistant fever?
Complete Exam
Indications for types of Physical Exam if pt is hospitalized for fever?
Serial Exams
Screen Labs for Evaluating a Fever
- CBC
- UA
- Cultures
- Serum Chemistry
Other tests driven by DDx:
- Serology
- ANA
- ESR
When would you use invasive testing in evaluation of a fever?
When all else fails
The normal ranges for a lab value encompass ___% of observations including 2 SD.
95.4%
Given the high inclusion rate in the normal range of a lab value, what should we think if a value is abnormal?
Disease Oriented!