Myxedema coma (patient information)
Template:Myxedema Coma For the clinician page on this topic, click here. Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sophia Saad, Associate Editor - WikiDoc [2]
Overview
Myxedema coma is the most severe, life-threatening form of an underactive thyroid (hypothyroidism). It is a medical emergency. Despite its name, most people are not actually in a coma — but they are very ill, with a dangerously slowed body, confusion or reduced alertness, and a low body temperature. It usually happens in someone whose hypothyroidism was undiagnosed, undertreated, or who stopped their thyroid medicine, and is often triggered by another illness such as an infection.[1][2]
What are the symptoms?
Warning signs that need emergency care include:
- Feeling extremely cold, or a low body temperature
- Severe drowsiness, confusion, slurred speech, or being hard to wake
- Very slow heartbeat and slow, shallow breathing
- Puffy face, swelling, dry skin, hoarse voice
Milder, longer-standing signs of an underactive thyroid — tiredness, weight gain, constipation, feeling cold, dry skin, low mood, memory problems — may come first over weeks to months.[3][1]
What causes it?
Myxedema coma develops when severe hypothyroidism is pushed over the edge by a stress or trigger, such as:
- Infection (for example, pneumonia)
- Cold exposure, especially in winter
- Stopping thyroid hormone medicine
- Surgery, trauma, heart attack, or stroke
- Certain medicines (sedatives, opioids/narcotics, amiodarone, lithium, water pills/diuretics)[2][1][3]
Who is at highest risk?
- Older adults, especially women
- People with known but untreated or undertreated hypothyroidism
- People who have stopped their levothyroxine
- Winter/cold months[1][2]
How is it diagnosed?
Doctors diagnose it based mainly on the picture at the bedside — low body temperature, slowed mental state, and a trigger — and start treatment right away. Blood tests (thyroid hormones, sodium, blood sugar, cortisol) confirm it, but treatment is not delayed while waiting for results.[1][4]
When to seek urgent medical care
Call 911 or go to an emergency department immediately for anyone with known or suspected thyroid disease who becomes very cold, unusually drowsy or confused, or hard to wake. This is a life-threatening emergency treated in the intensive care unit. If you call for help, tell the emergency team that the person has a thyroid problem and what thyroid medicine they take — this helps doctors recognize the emergency quickly.[1][5]
Treatment
Treatment is given in the hospital/ICU. Doctors usually start steroid medicine first (to protect against a linked adrenal-gland emergency), then give thyroid hormone through the vein, along with warming, breathing and blood-pressure support, and treatment of the trigger. See the clinician page for details.[1][4]
How to prevent it
The best prevention is taking thyroid medicine (levothyroxine) exactly as prescribed, not stopping it, keeping follow-up blood tests, and seeking care early for infections or new illness.[2][1]
Outlook
Even with modern intensive care, myxedema coma is serious. Reported death rates range widely — about 7% in a recent large US hospital study, but as high as 25–60% in other/older series. Early recognition and treatment improve survival.[6][7][2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Chaker L, Papaleontiou M. Hypothyroidism. JAMA. 2025.
- ↑ 2.0 2.1 2.2 2.3 2.4 Chaker L, Razvi S, Bensenor IM, et al. Hypothyroidism. Nature Reviews Disease Primers. 2022;8(1):30.
- ↑ 3.0 3.1 Cruz-Flores S. Neurological Complications of Endocrine Emergencies. Curr Neurol Neurosci Rep. 2021;21(5):21.
- ↑ 4.0 4.1 Jonklaas J, Bianco AC, Bauer AJ, et al. Guidelines for the Treatment of Hypothyroidism. Thyroid. 2014;24(12):1670-1751.
- ↑ Bridwell RE, Willis GC, Gottlieb M, et al. Decompensated Hypothyroidism: A Review for the Emergency Clinician. Am J Emerg Med. 2021;39:207-212.
- ↑ Chen DH, Hurtado CR, Chang P, et al. Clinical Features and Outcomes of Myxedema Coma in Patients Hospitalized for Hypothyroidism: Analysis of the United States National Inpatient Sample. Thyroid. 2024;34(4):419-428.
- ↑ Taylor PN, Medici MM, Hubalewska-Dydejczyk A, Boelaert K. Hypothyroidism. Lancet. 2024;404(10460):1347-1364.