Thermoregulation - The body’s ability to keep its temperature within certain boundaries independant of environmental conditions

• Thermoregulatory centre is in the hypothalamus
• too hot: sweat, vasodilation of vessels, hairs lie flat
• too cold: decreased sweart, vasoconstriction, shivering, metabolism of brown fat

Fever - Abnormal elevation of the body temperature as part of a specific biological response that is mediated and controlled by the CNS

Pathophysiology

• Pyrogens (IL, TNF-a) increase PGE-2 production - acts on hypothalamus to create a systemic response and modify sympathetic output leading to ⬆️  BMR and vasoconstriction
• This raises body temp to match a new higher temp set point

Patters of fever

• Intermittent fever - Temp returns to acceptable value at least one in 24 hours. E.g. in speticaemia temp may be normal during day and reaches a peak in the evening
• Remittent fever - fever spikes and falls without a return to normal temp. E.g. TB, viral diseases, bacterial infections
• Sustained fever - temp continuously high
• Relapsing fever - peiods of febrile periods interspersed with normal periods

Causes:

• Acute phase infection
• Polymyalgia rheumaticia
• SLE