What is the differential diagnosis for a hospitalized patient with a core temperature of 95 °F (hypothermia)?

Differential Diagnosis for Hospitalized Patient with Temperature of 95°F

In a hospitalized patient with a core temperature of 95°F (35°C), you must immediately consider: environmental/iatrogenic exposure (cold room, unwarmed IV fluids), sepsis, severe hypothyroidism (myxedema coma), medication effects (particularly antipsychotics), acute spinal cord injury, diabetic ketoacidosis, multisystem trauma, and prolonged cardiac arrest as your primary differential diagnoses 1, 2.

Primary Etiologies in Hospitalized Patients

The differential for inpatient hypothermia differs fundamentally from environmental exposure cases. Hospital-acquired hypothermia is predominantly secondary to acute illness, comorbidities, iatrogenic factors, or medications that impair thermoregulation 2.

Most Common Causes to Evaluate:

Iatrogenic/Environmental Factors:

• Cool hospital room temperature
• Unwarmed intravenous fluids during resuscitation
• Prolonged surgical exposure
• Use of anesthesia 3, 2

Infectious:

• Sepsis is a leading cause - look for signs of infection, hemodynamic instability, elevated lactate 1, 2

Endocrine:

• Severe hypothyroidism (myxedema coma) - check for history of thyroid disease, bradycardia, altered mental status, delayed reflexes 1
• Diabetic ketoacidosis 1
• Adrenal insufficiency

Neurological:

• Acute spinal cord injury - impairs thermoregulation below the lesion level 1
• Stroke affecting hypothalamus
• Reduced functional status/immobility 2

Medication-Induced:

• Antipsychotics (quetiapine, risperidone, olanzapine) - even at stable doses without recent adjustments 4
• Alcohol intoxication - dominant precipitating factor 5
• Sedatives and other CNS depressants

Trauma:

• Multisystem trauma with prolonged exposure 1
• Severity of injury correlates with hypothermia risk 3

Cardiovascular:

• Prolonged cardiac arrest 1
• Shock states

Key Risk Factors to Identify

Patient-specific factors that increase suspicion 2:

• Advanced age (elderly at highest risk)
• Male sex
• Alcohol use disorder
• Reduced functional status/immobility
• Pre-existing endocrine or neurological disorders

Critical Pitfalls to Avoid

1. Do not assume environmental exposure alone - in hospitalized patients, hypothermia is almost always multifactorial or secondary to underlying pathology 2

2. Check medication lists carefully - antipsychotic-induced hypothermia can occur even with chronic stable dosing, not just new medications 4

3. Measure core temperature accurately - peripheral measurements underestimate severity 6

4. Remember the mortality risk - in-hospital mortality ranges 13-26%, with trauma patients having significantly higher mortality (OR ~5.18) 2

5. Hypothermia below 32°C (89.6°F) carries severe mortality risk and requires aggressive intervention 3

Algorithmic Approach to Workup

Immediate assessment:

• Confirm core temperature (rectal, esophageal, or bladder probe)
• Review recent procedures, IV fluid administration, room temperature
• Complete medication reconciliation (focus on antipsychotics, sedatives)
• Assess for sepsis (vital signs, lactate, blood cultures)

Laboratory evaluation:

• Thyroid function tests (TSH, free T4) for myxedema coma
• Blood glucose for DKA/hypoglycemia
• Complete metabolic panel for electrolyte disturbances
• Arterial blood gas for acidosis
• Coagulation studies (hypothermia impairs coagulation) 3

Targeted history:

• Trauma or prolonged immobilization
• Neurological symptoms suggesting stroke or spinal cord injury
• Symptoms of infection
• Alcohol or drug use

The key is recognizing that hospitalized hypothermia represents organ system failure or iatrogenic exposure rather than simple environmental cold 2. Your differential should prioritize reversible causes like sepsis, medication effects, and endocrine emergencies while simultaneously initiating rewarming protocols.