Subacute or chronic hypothermia of non-environmental origin

Specialty: General.

• persistent low body temperature of organic cause
• chronic non-environmental body cooling

Why it occurs

• Severe uncontrolled hypothyroidism or incipient myxedema coma (critical decrease in basal metabolism and metabolic heat production)
• Chronic adrenal insufficiency or occult adrenal crisis (cortisol deficiency that alters the thermogenic response and vascular tone)
• Recurrent or persistent hypoglycemia (lack of energy substrate for shivering and non-shivering thermogenesis in tissues)
• Central hypothalamic dysfunction due to tumors of the sella turcica, sarcoidosis, consequences of radiotherapy or traumatic brain injury
• Severe uremia or terminal liver failure (due to accumulation of metabolic toxins that depress the thermoregulatory center).

Initial workup

Measurement of core temperature using a low-range thermometer (rectal or esophageal), complete thyroid profile (TSH, free T4, total T3), morning serum cortisol, capillary and serum glucose, urea nitrogen, serum creatinine, and brain MRI focused on the hypothalamic-pituitary region.

Standard management

• Treatment of the underlying cause: Levothyroxine sodium — dose adjusted by specialist if there is severe hypothyroidism
• Hydrocortisone — 100 mg intravenously every 8 hours if adrenal crisis is suspected before thyroid replacement
• Passive external warming (thermal blankets, warm environment) and replacement of warm intravenous fluids (37-40 °C) in a hospital environment.