Causes and Evaluation of Prolonged Unknown Fever (PUO

INTRODUCTION
Body temperature is normally maintained within a range of 37 – 38°c ,
normal body temperature is generally considered to be 37°c .
BODY TEMPERATURE

PHYSIOLOGY
Normal body temperature is
maintained by a complex regulatory
system in the anterior hypothalamus,
preoptic area, temperature sensitive
area, thermal set point.

PATHOGENESIS
Substances the mediate the elevation of core body temperature
There are two types; exogenous and endogenous pyrogens.
PYROGENS
EXOGENOUS PYROGENS
 It is derived from outside of the host, such as microorganisms, toxins and
microbial products
 They are generally large molecules – cannot pass blood brain barrier
 They induce the release of endogenous pyrogens from macrophages.

PATHOGENESIS
ENDOGENOUS PYROGENS
 Endogenous pyrogens are derived from the macrophages.
 They are small molecules – can pass blood brain barrier
 Pyrogen cytokines trigger the
hypothalamus to release PGE2,
resulting in:
1. Resetting of thermostatic
temperature
2. Activation of vasomotor center
3. Vasodilatation
4. Heat production

PYREXIA OF UNKNOWN ORIGIN
ORIGINAL DEFINITION (Petersdotf anf Beeson, 1961)
 Temperature ≥ 38.3ºC (101ºF) on several occasions
 Fever ≥ 3 weeks
 Failure to reach a diagnosis despite 1 week of inpatient investigations or
3 outpatient visits
NEW DEFINITION (Petersdotf anf Beeson, 1961)
Temperature ≥ 38.3ºC (101ºF) lasting for more than 14 days without an
obvious cause despite a complete history, physical examination and routine
screening with laboratory evaluation

FACTORS
FACTORS THAT MAY HAVE CONTRIBUTED TO
THE DIFFICULTY IN FINDING THE CAUSE OF FEVER INCLUDE:
 A common illness that does not have the usual symptoms – may be
asymptomatic
 Illness whose symptoms appear later
 Illnesses with possibly delayed positive test
 Person is unable to communicate about other symptoms
 Genetic condition that causes periodic fever.

COMMON CAUSES
COMMON CAUSES OF PYREXIA OF UNKNOWN ORIGIN
40%
25%
15%
10%
10%
Infection (40%) Malignancy (25%)
Autoimmune Disease (15%) Others/ Miscellaneous (10%)
Undiagnosed (10%)

CLASSIFICATION
DURACK AND STREET’S CLASSIFICATION
1. Classical
2. Nosocomial
3. Neutropenic
4. Pyrexia of unknown origin with HIV infection

1. CLASSICAL
CLASSIC PYREXIA OF UNKNOWN ORIGIN
 Temperature >38.3°C (100.9°F)
 Duration of >3 weeks
 Evaluation of at least 3 outpatient visits or 3 days in hospital
AETIOLOGIES
1. Infections
2. Malignancies
3. Collagen vascular disease
4. Others / miscellaneous which includes drug-induced fever

1. CLASSICAL
A. INFECTIONS
 Bacterial
Abscesses, tuberculosis, uncomplicated UTI, endocarditis, osteomyelitis,
sinusitis, prostatitis, cholecystitis, empyema, biliary tract infection,
brucellosis, typhoid, etc.
 Viral
Cytomegalovirus, infectious mononucleosis, HIV, etc.
 Parasites
Malaria, toxoplasmosis, leishmaniasis, etc.
 Fungal
Histoplasmosis, etc.
As the duration of fever increases, infectious etiology decreases. Malignancy and
factitious fevers are more common in patients with prolonged pyrexia of unknown origin

1. CLASSICAL
B. MALIGNANCIES
HEMATOLOGICAL
1. Lymphoma
2. Chronic leukemia
NON-HAEMATOLOGICAL
1. Renal cell cancer
2. Pancreatic cancer
3. Colon cancer
4. Hepatoma

1. CLASSICAL
C. COLLAGEN VASCULAR DISEASE / AUTOIMMUNE DISEASE
 Temporal arthritis
 Rheumatoid arthritis
 Rheumatoid fever
 Inflammatory bowel disease
 Reiter’s syndrome
 Systemic lupus erythematosus
 Polyarthritis nodosa
 Giant cell arthritis
 Kawasaki disease

1. CLASSICAL
C. MISCELLANEOUS
 Hyperthyroidism
 Alcoholic hepatitis
 Inflammatory bowel disease
 Deep venous thrombosis
DRUGS
 Allopurinol
 Captopril
 Cimetidine
 Clofibrate
 Erythromycin
 Heparin
 Hydralazine
 Hydrochlorothiazide
 Isoniazid
 Meperidine
 Methydopa
 Nifedipine
 Nitrofurantoin
 Penicillin
 Phenytoin
 Procainamide
 Quinidine

1. CLASSICAL
C. MISCELLANEOUS
FACTITIOUS FEVER
Central
1. Brain tumor
2. Hypothalamic dysfunction
Peripheral
1. Hyperthyroidism
2. Pheochromocytoma
Munchausen syndrome
Munchausen by proxy
THERMOREGULATORY DISORDER

FEVER PATTERN
• Intermittent Fever
 Any fever characterized by intervals of normal temperature
 Malaria, pyaemia, septicemia
• Continuous Fever
 Temperature remains above normal throughout the day and does
not fluctuate more than 1C in 24 hours
 Lobar pneumonia, Typhoid, Meningitis, UTI, Brucellosis
• Remittent Fever
 A fever pattern in which temperature varies during each 24 hour
period but never reaches normal.
 Enteric Fever, Bacterial Endocarditis, Viral Pneumonia

FEVER PATTERN
• Relapsing Fever
An acute infection with recurrent episodes of fever caused by
spirochetes of the genus Borrelia which are borne by ticks or lice.
• Undulant Fever
An infectious disease due to the bacteria Brucella.
It is called undulant because the fever is typically undulant, rising and
falling like a wave.
It is also called brucellosis after its bacterial cause

2. NOSOCOMIAL
NOSOCOMIAL PYREXIA OF UNKNOWN ORIGIN
 Temperature > 38.3°C
 Patient hospitalized ≥ 24 hours but no fever or incubating on admission
 Evaluation of at least 3 days
 More than 50% of patients with nosocomial PUO are due to infection
 Focus on sites where occult infections may be sequested, such as:
- Sinusitis of patients with NG or Oro-tracheal tubes
- Prostatic abscess in a man with urinary catheter
 25% of non-infectious cause includes:
- Acalculous colecystitis
- Deep vein thrombophlebitis
- Pulmonary embolism

3. NEUTROPENIC
IMMUNE DEFICIENT / NEUTROPENIC PUO
 Temperature >38.3°C
 Neutrophil count ≤ 500 per mm3
 Evaluation of at least 3 days
 Patients on chemotherapy or immune deficiencies are susceptible to:
- Opportunistic bacterial infection
- Fungal infections such as candidiasis
- Infections involving catheters
- Perianal infections
 Examples of etiological agent:
- Aspergillus
- Candida
- CMV
- Herpes simplex

4. HIV-ASSOCIATED
IMMUNE DEFICIENT / NEUTROPENIC PUO
 Temperature > 38.3°C
 Duration of > 4 weeks for outpatients, > 3 days for inpatients
 HIV infection confirmed
 HIV infection alone may be a cause of fever
 Common secondary causes include:
- Tuberculosis
- CMV infection
- Non-hodgkin lymphoma
- Drug-induced fever

CLINICAL APPROACH
PYREXIA OF UNKNOWN ORIGIN : A CLINICAL APPROACH
1. Onset
a. Acute
b. Gradual
2. Character
2. Antecedents
a. Dental extraction
b. Urinary catheterization
HISTORY OF PRESENTING ILLNESS

CLINICAL APPROACH
4. Associated symptoms
 Chills and rigors
 Night sweats
 Loss of weight
 Cough and dyspnea
 Headache
 Joint pain
 Abdominal pain
 Bone pain
 Sore throat
 Dysuria and rectal pain
 Altered bowel habit
 Skin rash

CLINICAL APPROACH
PAST MEDICAL HISTORY
PAST SURGICAL HISTORY
DRUG HISTORY
FAMILY HISTORY

CLINICAL APPROACH
 Travel
 Residential area
 Occupation
 Contact with domestic / wild animals / birds
 Diet history
 Sexual orientation
 Close contact with TB patients

PHYSICAL EXAMINATION
 Pattern of fever – continuous, intermittent, relapsing
 Ill or not ill
 Weight loss – chronic illness
 Skin rash
GENERAL
HANDS
 Stigmata of infective endocarditis
 Vasculitis changes
 Clubbing
 Presence of arthropathy
 Raynaud’s phenomenon

 Drug injection sites (IV drug usage)
 Epithrochlear and axillary nodes (lymphoma, sarcoidosis, focal infection)
 Skin
ARMS
HEAD AND NECK
 Feel temporal arteries (tender and thicken)
 Eyes – iritis / conjunctivitis
 Jaundice (ascending cholangitis)
 Fundus – choroidal tubercle (miliary TB), Roth’s spot (infective
endocarditis) and retinal hemorrhage (leukemia)
 Lymphadenopathy

 Butterfly rash
 Mucous membranes
 Seborrhoic dermatitis (HIV)
 Mouth ulcers (SLE)
 Buccal candidiasis
 Teeth and tonsil infections (abscess)
 Parotid enlargement
 Ears – otitis media
FACE AND MOUTH
CHEST
 Bony tenderness
 Cardiovascular – murmurs
 Respiratory – signs of pneumonia, tuberculosis, empyema and lung
cancer

 Rose colored spot – typhoid fever
 Hepatomegaly
 Splenomegaly – haemopoietic malignancy, IE, malaria
 Renal enlargement – renal cell carcinoma
 Testicular enlargement – seminoma
 Penis & scrotum – discharge/rash
 Inguinal ligament
Per-rectal exam
Mass / tenderness in rectum/pelvis (abscess, carcinoma, prostatitis)
Vaginal examination
Collection of pelvic pus/ pelvic inflammatory disease
ABDOMEN

 Signs of meningism (chronic TB meningitis)
 Focal neurological signs (brain abscess, mononeuritis multiplex in
plyarthritis nodosa)
CENTRAL NERVOUS SYSTEM

a. Full blood count
b. ESR and CRP
c. BUSE
d. LFTs
e. Blood culture
f. Serum virology
g. Urinalysis and culture
h. Sputum culture and sensitivity
i. Stool FEME and occult blood
j. Chest x-ray
k. Mantoux test
INVESTIGATION
STAGE 1 – SCREENING TESTS

a. Repeat history and examination
b. Protein electrophoresis
c. CT (chest, abdomen, pelvis)
d. Autoantibody screen
e. Electrocardiogram (ECG)
f. Bone marrow examination
g. Lumbar puncture
h. Temporal artery biopsy
i. HIV test counselling
j. Ultrasonography
INVESTIGATION
STAGE 2

INVESTIGATION
STAGE 3
• Tuberculosis, malignancy, Pneumocystis carinii pneumoniaChest radiograph
• Abscess, malignancy
CT of abdomen or pelvis with contrast
agent
• Infection, malignancyGallium 67 scan
• Occult septicemiaIndium-labeled leukocytes
• Acute infection and inflammation of bones and soft tissueTechnetium Tc 99m
• Malignancy, autoimmune conditionsMRI of brain
• Malignancy, inflammation
PET scan
• Bacterial endocarditis
Transthoracic or transesophageal
echocardiography
• Venous thrombosisVenous Doppler study

a. Treat TB
b. Endocarditis
c. Vasculitis
d. Trial of aspirin / steroids
INVESTIGATION
STAGE 4

DIAGNOSIS
 More invasive testing, such as LP or biopsy of bone
marrow, liver, or lymph nodes, should be performed
only when clinical suspicion shows that these tests are
indicated or when the source of the fever remains
unidentified after extensive evaluation.
 When the definitive diagnosis remains elusive and the
complexity of the case increases, an infectious
disease, rheumatology, or oncology consultation may
be helpful.

THERAPEUTIC TRIALS
WHAT IS THE BEST THERAPEUTIC TRERAPY FOR PUO PATIENTS?
Therapeutic trials consist of combination of broad spectrum antibiotics and
are given in :-
1. Patient who is very sick to wait.
2. All tests have failed to uncover the etiology.

PROGNOSIS
 Prognosis is determined primarily by the underlying disease.
 Outcome is worst for neoplasms.
 PUO patients who remain undiagnosed after extensive evaluation generally
have a favorable outcome and the fever usually resolves after 4 - 5 weeks

SUMMARY
 PUO is often a diagnostic dilemma, quandary.
 Infections comprise ~30% of cases
 Bone marrow biopsies are of low diagnostic yield
 Diagnostic approach should occur in a step-wise fashion based on the H&P
 Patient’s that remain undiagnosed generally have a good prognosis

REFERENCES
1. Nelson Essenssials Of Pediatrics 6th Edition
2. Harrison’s Principles Of Internal Medicine 18th Edition.
3. Mandell, Bennet & Dolin’s, Principle Of Infectious Disease 6th Edition.

Causes and Evaluation of Prolonged Unknown Fever (PUO

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Causes and Evaluation of Prolonged Unknown Fever (PUO

Similar to Causes and Evaluation of Prolonged Unknown Fever (PUO (20)

More from yuyuricci

More from yuyuricci (20)

Recently uploaded

Recently uploaded (20)

Causes and Evaluation of Prolonged Unknown Fever (PUO