From the Guidelines
Altered mental status is a highly sensitive clinical finding in myxedema coma, present in the majority of cases, and its presence warrants immediate medical attention. Myxedema coma represents the most severe form of hypothyroidism and is a medical emergency requiring immediate treatment, as outlined in the management guidelines for immune-related adverse events in patients treated with immune checkpoint inhibitor therapy 1. The altered mental status in these patients typically manifests as confusion, lethargy, obtundation, stupor, or frank coma, and is a key diagnostic feature that guides the initiation of prompt treatment.
Clinical Presentation and Diagnosis
The pathophysiological mechanisms underlying altered mental status in myxedema coma include reduced cerebral blood flow from bradycardia and hypotension, hyponatremia, hypoglycemia, and direct effects of thyroid hormone deficiency on brain metabolism. According to the guidelines, hospital admission is required for developing myxedema, characterized by bradycardia, hypothermia, and altered mental status, with inpatient endocrinology consultation to assist with IV levothyroxine dosing, steroids, and supportive care 1.
Treatment and Management
Treatment must be initiated promptly with intravenous levothyroxine (T4) and supportive care, including mechanical ventilation, temperature management, treatment of precipitating factors, and correction of electrolyte abnormalities. The guidelines recommend holding immune checkpoint inhibitor therapy until symptoms resolve to baseline with appropriate supplementation, and endocrine consultation to assist with rapid hormone replacement 1.
Key Considerations
It is crucial to recognize altered mental status as a key diagnostic feature of myxedema coma, given the high mortality rate associated with this condition despite appropriate treatment. The presence of altered mental status, along with other clinical features such as bradycardia and hypothermia, should prompt immediate initiation of treatment and supportive care, as outlined in the guidelines 1.
From the Research
Sensitivity of Altered Mental Status in Myxedema Coma
- The sensitivity of altered mental status in myxedema coma is a critical aspect of diagnosis, as it is a key feature of the condition 2, 3, 4, 5, 6.
- A study published in 2015 developed an objective screening tool for myxedema coma, which included altered mental status as one of the criteria, and reported a sensitivity and specificity of about 80% 4.
- Another study published in 2021 reported a case of myxedema coma in a 58-year-old male who presented with altered mental status, and highlighted the importance of prompt recognition and treatment 3.
- Altered mental status is a common presentation of myxedema coma, and can range from mild confusion to coma 2, 5.
- The clinical triad of myxedema coma includes altered mental status, hypothermia, and the presence of a precipitating factor 2.
Diagnostic Criteria
- The diagnostic criteria for myxedema coma include altered mental status, hypothermia, and symptoms related to the slowing of other organ systems 3, 4.
- A screening tool developed in 2015 included six variables: heart rate, temperature, Glasgow coma scale, TSH, free thyroxine, and precipitating factors 4.
- The tool has a sensitivity and specificity of about 80%, and can be used to rapidly diagnose myxedema coma and expedite treatment 4.
Clinical Presentations
- Myxedema coma can present with a range of symptoms, including altered mental status, hypothermia, hypoventilation, and cardiovascular instability 2, 3, 5.
- The condition is more common in older women with hypothyroidism, but can also occur in other populations, including children 5.
- Prompt recognition and treatment of myxedema coma are critical to reducing mortality and improving outcomes 2, 3, 6.