Differential Diagnosis for Low Body Temperature (95.5°F) in a 74-Year-Old Male

After eliminating hypothermia as the potential cause, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Hypothyroidism: This condition is a common cause of low body temperature in elderly individuals. The decreased metabolic rate associated with hypothyroidism can lead to a lower than normal body temperature. Given the patient's age and otherwise good health, hypothyroidism is a plausible explanation.

• Other Likely Diagnoses

  • Anemia: Severe anemia can lead to a decrease in body temperature due to reduced oxygen delivery to tissues and a subsequent decrease in metabolic rate.
  • Malnutrition: Poor nutritional status can affect the body's ability to regulate temperature, leading to hypothermia or low body temperature.
  • Medication side effects: Certain medications, such as sedatives, anesthetics, or beta-blockers, can cause a decrease in body temperature as a side effect.
  • Sleep disorders: Certain sleep disorders, such as sleep apnea, can lead to fluctuations in body temperature.

• Do Not Miss Diagnoses

  • Sepsis: Although sepsis is often associated with fever, it can also cause hypothermia, especially in elderly individuals. It is crucial to consider sepsis as a potential cause, as it can be life-threatening if left untreated.
  • Adrenal insufficiency: This condition, also known as Addison's disease, can cause a decrease in body temperature due to the lack of cortisol and aldosterone production.
  • Stroke or cerebral vasculature accident: In rare cases, a stroke can affect the hypothalamus, leading to abnormalities in temperature regulation.

• Rare Diagnoses

  • Neurodegenerative diseases (e.g., Parkinson's disease, multiple system atrophy): Certain neurodegenerative diseases can affect the body's ability to regulate temperature.
  • Dysautonomia: This condition, characterized by autonomic nervous system dysfunction, can lead to abnormalities in temperature regulation.
  • Tumor or cancer: Rarely, a tumor or cancer can affect the hypothalamus or other temperature-regulating centers, leading to low body temperature.