Myxedema Coma: Recognizing and Treating Severe Hypothyroidism in Emergencies

When your body runs out of thyroid hormone, it doesn’t just slow down-it shuts down. Myxedema coma, once thought of as a rare condition only seen in patients lying unconscious in a hospital bed, is now understood as a life-threatening crisis that can strike anyone with untreated or poorly managed hypothyroidism. It doesn’t always begin with coma. Sometimes it starts with confusion, cold skin, or a heart rate so slow it’s hard to feel. And if you wait for lab results before acting, you might already be too late.

What Really Happens in Myxedema Coma?

Myxedema coma isn’t just a drop in thyroid hormone levels. It’s the collapse of multiple systems. Your body’s thermostat fails. Your lungs stop responding to low oxygen. Your heart can’t pump hard enough. Your kidneys can’t hold onto sodium. And your brain? It starts to fog over-not from stress, not from aging, but because your cells are starving for energy.

This isn’t a gradual decline. It’s a cascade. One small trigger-a cold night, a missed pill, a urinary infection-can push someone with years of undiagnosed hypothyroidism over the edge. The American Family Physician reports that 98% of cases involve extreme lethargy. Eighty to ninety percent have a core temperature below 35°C (95°F). Over 70% have dangerously low sodium. And in nearly half, breathing slows to fewer than 12 breaths per minute.

Women over 60 are most at risk-three times more likely than men. But men don’t escape unscathed. In fact, men often wait longer for diagnosis because their symptoms get dismissed as "just getting older." A 2023 Healthline survey found that men accounted for 40% of diagnostic delays, even though they make up only 25% of cases.

The Signs You Can’t Afford to Miss

Forget the textbook image of a comatose patient. Real cases look different. A 72-year-old woman is found sitting in her chair, unresponsive, wearing three sweaters in a 22°C room. Her daughter says she’s been "just tired" for months. Her pulse is 48 beats per minute. Her skin is dry, puffy around the eyes. She hasn’t had a bowel movement in a week. Her blood test shows sodium at 128 mmol/L. She’s not depressed. She’s not demented. She’s in myxedema crisis.

The diagnostic triad is simple: altered mental status, hypothermia, and a precipitating event. But the details matter. Mental status isn’t always coma. It could be confusion, slurred speech, or just not answering questions. Hypothermia doesn’t mean freezing. It means your body can’t warm itself anymore-even with blankets. And the precipitating event? Often something small: pneumonia, a UTI, stopping thyroid meds during a hospital stay, or even just being outside too long in winter.

Respiratory failure is silent until it’s too late. Carbon dioxide builds up because the brain stops telling the lungs to breathe. Oxygen drops. The body goes into a low-energy survival mode. That’s why many patients are found with shallow, irregular breathing. No snoring. No gasping. Just stillness.

Why Time Is the Enemy

Every hour of delay increases the chance of death by 10%. That’s not a guess. It’s from NCBI data published in 2023. The average time from symptom onset to treatment is 6 to 12 hours. But in hospitals with clear protocols, that drops to under 2 hours-and survival rates jump.

Why the delay? Because the symptoms mimic so many other things. Depression. Dementia. Stroke. Drug overdose. Even sepsis. In elderly patients, classic signs like weight gain, dry skin, or constipation are often absent. Instead, you get "apathetic hypothyroidism"-a quiet, withdrawn, cold patient who doesn’t complain. Doctors miss it. Families think they’re just tired.

Dr. Robert H. Eckel, former president of the American Heart Association, put it bluntly: "Treatment must not wait for laboratory confirmation." You don’t need a TSH level of 120 mIU/L to start. You need to suspect it-and act.

Emergency Protocol: What to Do Right Now

There’s no time for debate. If you suspect myxedema coma, start treatment before the lab report comes back. The steps are clear:

1. Secure the airway. Over half of these patients need intubation. Their breathing is too weak. Don’t wait for oxygen levels to crash. If they’re unresponsive and breathing shallowly-intubate.
2. Give thyroid hormone immediately. Start with 300-500 mcg of intravenous levothyroxine (T4). If the patient is in cardiac distress, add 10-20 mcg of liothyronine (T3) every 8 hours. The 2022 Endocrine Society update confirmed T3 improves survival in severe cases.
3. Warm slowly. No heating blankets. No warm IV fluids. Passive rewarming only. Cover with blankets. Monitor core temperature every 30 minutes. Aggressive rewarming before hormone levels rise can cause heart failure.
4. Treat the trigger. Infection is the cause in 30-50% of cases. Start broad-spectrum antibiotics immediately. Don’t wait for cultures. Pneumonia, UTIs, and sepsis are the usual suspects.
5. Correct sodium carefully. Hyponatremia is common, but correcting it too fast can destroy brain cells. Limit sodium correction to 4-6 mmol/L in the first 24 hours. Use fluids with caution.

The DIMES mnemonic helps remember triggers: Drugs, Infection, Myocardial infarction/CVA, Exposure to cold, Stroke. Check for each one-quickly.

What Not to Do

There are traps everywhere. One big mistake? Waiting for thyroid tests. Results take hours. By then, it’s too late. Another? Giving glucose too early. Many patients have low cortisol too. If you give sugar without checking cortisol levels, you can trigger adrenal crisis.

Don’t assume they’re just "sleepy." A patient who doesn’t respond to pain or voice isn’t being lazy-they’re dying. Don’t dismiss coldness as "just being sensitive." In myxedema, the body can’t generate heat anymore.

And never, ever use active warming. Hot water bottles, heating pads, warm IV fluids-they sound logical. But they force the body to burn more energy before the thyroid hormone is in the system. That can crash the heart.

Real Stories Behind the Numbers

A 68-year-old woman in Wisconsin stopped her levothyroxine during a hospital stay for pneumonia. Three days later, she was found curled up on her kitchen floor, unresponsive. Her temperature was 31°C. Her TSH was 240 mIU/L. She spent 11 days in the ICU. She recovered-but her daughter says, "We almost lost her because no one thought it could be her thyroid."

A man in his 50s in Auckland went to his GP three times with "brain fog" and fatigue. Each time, he was told to "get more sleep." He stopped taking his meds during a stressful period. Three weeks later, he was found unconscious in his car. His T4 was undetectable. He survived-but had to relearn how to walk.

These aren’t rare. A 2022 survey of 427 hypothyroid patients found 18% had experienced a near-miss event. The top three triggers? Hospitalizations (47%), infections (32%), and cold exposure (28%).

What’s Changing in 2026

The FDA approved a new IV thyroid hormone formulation called Thyrogen® in January 2023. It absorbs faster, which matters when every minute counts. Research in 2023 showed that elevated thyrotropin receptor antibody levels can predict decompensation before symptoms even appear-useful for high-risk patients.

Point-of-care thyroid testing is in phase 3 trials. Devices that give TSH and T4 results in 15 minutes could soon be in ERs. That’ll cut delays dramatically.

But the biggest change? Awareness. More hospitals now have formal protocols. In the U.S., 87% of hospitals have myxedema coma guidelines in their emergency departments as of 2022. Still, gaps remain. Uninsured patients wait 35% longer for treatment and have 22% higher death rates.

What Comes After

Survivors often need weeks to recover. Mental clarity returns slowly. Energy takes months. Many need higher thyroid doses than before. Long-term, they’re at higher risk for heart problems. But if treated fast, most go on to live normal lives.

The key isn’t just treatment-it’s prevention. Patients with hypothyroidism must never stop their meds without a doctor’s order. Even a few days without levothyroxine can be dangerous. If you’re hospitalized, remind staff you’re on thyroid hormone. If you’re cold, tired, or confused, and you have hypothyroidism-say so. Loudly.

Myxedema coma is rare. But it’s not mysterious. It’s predictable. And with the right knowledge, it’s preventable. The next time someone says, "She’s just getting old," ask: "Could it be her thyroid?""