Chills without documented fever

Specialty: General.

• cold shivering without hyperthermia
• shivering without fever
• cold spells of organic origin

Why it occurs

• Dysautonomia or instability of the autonomic nervous system (where the peripheral vasoconstrictor response is activated abnormally, simulating the thermal rise phase of fever)
• Severe or subclinical decompensated primary hypothyroidism (marked reduction in thermogenesis due to low cellular metabolism that generates an extreme sensation of cold with involuntary trembling to produce heat)
• Adverse reactions or withdrawal to central nervous system depressant drugs (benzodiazepines, opiates, alcohol or beta blockers)
• Episodes of severe or reactive hypoglycemia (discharge of catecholamines to mobilize glucose that causes paleness, cold sweats and tremors)
• Acute infections located in the incubation or pre-febrile phase (where the pyrogen has not yet raised the hypothalamic set point to a measurable level).

Initial workup

Repeated monitoring of body temperature with a calibrated thermometer in different sites (rectal, axillary), fasting capillary blood glucose and during the onset of chills, complete thyroid profile, serum electrolyte profile, and blood cultures if there is suspicion of occult bacteremia without fever.

Standard management

• Paracetamol — 500 mg orally only if a pre-febrile phase of an active infectious process is suspected
• Clonazepam — 0.25 mg orally in a single dose to attenuate chills of autonomic origin or induced by high-intensity anxiety
• Physical active warming measures such as the use of forced air electric blankets at body temperature.