T13: Pyrexia of unknown origin

Question 1

What is the normal temperature in a healthy 18-40-year-old?

Answer 1

36.8 +/- 0.4 degrees Celsius

Question 2

List 3 causes of physiological elevations in body temperature

Answer 2

1. postprandial
2. pregnancy
3. Menstruation

Question 3

List 4 ways through which we measure temperature

Answer 3

1. Oral
2. Rectal
3. Axillary
4. Tympanic membrane

Question 4

The least reliable way of measuring temperature

Answer 4

Axillary

Question 5

The most commonly used but less reliable in respiratory diseases way to measure temperature

Answer 5

Oral

Question 6

How does rectal temperature differ from oral temperature?

Answer 6

It is > 0.4 degrees Celsius

Question 7

How does the tympanic membrane method work and how does it differ from the oral method?

Answer 7

It measures heat radiation from the tympanic membrane. It is more variable than oral.

Question 8

PHYSIOLOGY OF THERMREGULATION: There is an ongoing balance between heat loss and production. List 4 ways through which heat is produced

Answer 8

1. Oxidation of nutrients
2. Cellular metabolism
3. Blood circulation
4. Involuntary contraction of muscles

Question 9

PHYSIOLOGY OF THERMREGULATION: There is an ongoing balance between heat loss and production. List 4 homeostatic mechanisms of heat regulation (excluding hypothalamic thermoregulation center)

Answer 9

Autonomic- sympathetic nerves
Endocrine- adrenal, thyroid, sweat gland
Metabolic- skin arterioles
Behavioral - take clothes on/ off (skeletal muscles- voluntary)

Question 10

Name the 3 endocrine organs involved in thermoregulation

Answer 10

1. Thyroid.
2. Adrenal
3. Sweat glands

Question 11

State whether this refers to fever or hyperthermia:

- Setpoint remains unchanged

Answer 11

Hyperthermia

Question 12

State whether this refers to fever or hyperthermia:

- Caused by: Neuroleptic malignant syndrome, Malignant hyperthermia, and serotonergic syndrome

Answer 12

Hyperthermia

Question 13

State whether this refers to fever or hyperthermia:

- Pathogenesis: Heat conservation and thermogenesis

Answer 13

Fever

Question 14

State whether this refers to fever or hyperthermia:

- Caused by infection, inflammation, cancer, medications, Thrombosis

Answer 14

Fever

Question 15

State whether this refers to fever or hyperthermia:

Pathogenesis: Exogenous heat exposure or endogenous heat protection (can rapidly become fatal)

Answer 15

Hyperthermia

Question 16

PATHOGENESIS OF FEVER: State whether the following refers to endogenous or exogenous pyrogens:

Derived from bacteria, viruses, parasites, fungi&raquo_space; stimulate other pyrogens via immune activation

Answer 16

Exogenous pathogens

Question 17

PATHOGENESIS OF FEVER: State whether the following refers to endogenous or exogenous pyrogens:
Pyrogenic cytokines: IL-1, IL-6, TNF, IFN-y, monocytes, lymphocytes, neutrophils. Stimulated by: inflammation, tissue necrosis, immune complexes

Answer 17

Endogenous pyrogens

Question 18

CONSEQUENCES OF FEVER:

At which temperature (rectal) do you get permanent brain damage?

Answer 18

> 41 degrees Celcius

Question 19

CONSEQUENCES OF FEVER:

Up to which temperature can you be spared from thermal injury?

Answer 19

41 degrees Celcius

Question 20

CONSEQUENCES OF FEVER:

At which temperature can you get: heat stroke and death

Answer 20

> 43 degrees Celcius

Question 21

We use the Durack and Street classification for Fever of Unknown Origin (FUO). List the 4 categories we look at

Answer 21

1. Classical FUO
2. Nosocomial FUO
3. immune-deficient FUO
4. HIV-related FUO

Question 22

Immunodeficient FUO is:

1. Also called?
2. Sources?
3. 4 Causative Organisms
4. Management?

Answer 22

• Neutropenic FUO
• Focal bacterial/ fungal bacteraemia/ catheter-related/ perianal
• S.aureus, TB, Gram negatives, HSV, CMV,fungal
• Broad spectrum A/B

Question 23

True or false:

More than 50% of nosocomial FUO is non-infectious and ~ 25% is infectious

Answer 23

false

Question 24

Which 7 groups of patients are at risk of Nosocomial infectious FUO?

Answer 24

1. Original surgical field
2. U-catheter
3. Intubated
4. Diarrhoea
5. IV lines
6. Prostheses
7. Source control

Question 25

What are some non-infectious causes of nosocomial FUO? (8)

Answer 25

1. 24 hours post-op 2. DVT 3. MI 4. Drug fever 5. Transfusion reaction 6. Neoplasm 7. Drug/ ETOH withdrawal 8. Acalculous cholecystitis

Question 26

Classical FUO has 4 categories (nature of pathology) with a mnemonic: INCUM. Name these

Answer 26

``` Infection Neoplasm Collagen vascular disease Undiagnosed Miscellaneous ```

Question 27

Account, in 4 ways, for the changing epidemiology of classical FUO

Answer 27

1. Ubiquitous use of A/B 2. Imaging 3. Tests: immunological, tumour antigen assays 4. Increased detection of rheumatologic diseases

Question 28

Rheumatological causes of classical FUO: List the causes in the following groups of patients: 1. Young patients 2. Old patients

Answer 28

1. Still's disease, SLE | 2. Temporal arteritis, polymyalgia rheumatica

Question 29

The modifying factors of classical FUO are age- and geographic location-related. explain.

Answer 29

Elderly= more neoplastic or multisystem disease causes Young= most no case identified (good prognosis, less likely underlying disease) LMI countries= more infections, HIC= more evenly distributed causes

Question 30

Explain, in 3 steps, your approach to FUO

Answer 30

Step 1: History, Physical exam, non-specific tests Step 2: More detailed Ix (decide on which organ/ system is involved) Step 3: Definitive Ix to confirm Dx

Question 31

True or false | Fever patterns are of great help in the diagnosis of FUO conditions

Answer 31

False

Question 32

Diagnose this patient: - Patient looks well - Temperature normal under supervision - Bizzare temperature chart > 41 with no diurnal variations and no correlation between pulse rate and temperature - No sweating when fever resolves - Evidence of self harm, injection - Normal ESR/CRP

Answer 32

Factitious fever