Severe Hypothyroidism: Myxedema coma is a life-threatening complication of untreated or severe hypothyroidism, characterized by hypothermia, altered mental status, and other systemic complications. This condition is directly related to the lack of thyroid hormones, which are essential for metabolism, heart rate, and overall bodily functions.

Adrenal Insufficiency: This condition, where the adrenal glands do not produce adequate amounts of hormones like cortisol, can present with similar symptoms to myxedema coma, including hypotension and altered mental status. It's a consideration because adrenal insufficiency can coexist with hypothyroidism.
Sepsis: Sepsis, especially when caused by an infection, can lead to a clinical picture that overlaps with myxedema coma, including hypotension, altered mental status, and organ dysfunction. The immune system's response to infection can mimic or exacerbate the symptoms of myxedema coma.
Hypoglycemia: Severe hypoglycemia can cause altered mental status, seizures, and even coma, which might be confused with myxedema coma, especially in diabetic patients or those with other metabolic disorders.

Carbon Monoxide Poisoning: Although less common, carbon monoxide poisoning can cause hypoxia, leading to altered mental status and coma, similar to myxedema coma. It's crucial to consider this diagnosis due to its high mortality rate if not promptly treated.
Stroke or Intracranial Hemorrhage: These conditions can cause sudden onset of altered mental status and can be life-threatening. They might not directly relate to myxedema coma but are critical to rule out due to their urgency and potential for severe outcomes.
Overdose or Toxicity: Certain drug overdoses or toxicities can present with altered mental status and coma, mimicking myxedema coma. Identifying and treating the underlying cause is crucial for patient survival.

Pituitary Apoplexy: A rare condition where there is sudden hemorrhage or infarction of the pituitary gland, which can lead to acute hypopituitarism, including adrenal insufficiency and hypothyroidism, presenting similarly to myxedema coma.
Traumatic Brain Injury: Although not directly related to myxedema coma, severe head injuries can cause altered mental status and coma, and it's essential to consider them in the differential diagnosis, especially in patients with a history of trauma.
Wernicke's Encephalopathy: A neurological disorder caused by thiamine deficiency, which can present with altered mental status, ophthalmoplegia, and ataxia. While distinct from myxedema coma, it's a condition that requires urgent treatment to prevent long-term brain damage.