2026 ETA/BTA Joint Consensus Statement: Management of Endocrine Emergencies — Myxedema Coma

Full title: Joint Consensus Statement by European Thyroid Association (ETA), British Thyroid Association (BTA), Society for Endocrinology (SfE): Management of Endocrine Emergencies — Myxedema Coma, published in European Thyroid Journal, 2026 Core positioning: Companion document to the thyroid storm consensus released in the same series. Myxedema coma (myxedema crisis) is a clinical diagnosis, treatment should be initiated immediately upon clinical suspicion, without waiting for full laboratory confirmation. Multidisciplinary ICU + endocrinology co-management is mandatory; key principle: stress-dose glucocorticoid administration prior to or together with thyroid hormone replacement to avoid unmasking adrenal crisis. Mortality remains 20–40%, mostly among elderly patients and those with multiple comorbidities.

1. Definition, Clinical Features & Precipitants

Myxedema coma represents end-stage decompensation of severe, long-standing hypothyroidism, most commonly from untreated Hashimoto thyroiditis, non-adherence to levothyroxine, or after total thyroidectomy. Classic triad: altered mental status, hypothermia, bradycardia.

• Associated findings: hypotension, hyponatremia, respiratory failure (hypoventilation, CO₂ retention), pericardial effusion, ileus.
• Common triggers: infection, cold exposure, sedatives/opioids, surgery, trauma, stroke, myocardial infarction, amiodarone, iodine excess.
• Atypical presentation in frail elderly: hypothermia may be masked, only confusion or reduced consciousness without coma.

2. Diagnostic Approach

1. Clinical suspicion first; lab tests for confirmation only. Key labs: TSH, FT4, FT3, random cortisol, glucose, sodium, renal function, arterial blood gas.

   Caveat: In critical illness / central hypothyroidism, TSH may not be markedly elevated. Also, be mindful of immunoassay interference (aligned with 2026 ETA assay interference guideline) when TFT results are discordant with clinical picture.

2. Popoveniuc scoring system used for risk stratification, but not used as rigid inclusion/exclusion rule.
3. Differential diagnosis: sepsis, stroke, hypothermia from other causes, drug intoxication, non-thyroidal illness syndrome.

3. Core Therapeutic Pillars (ICU setting, start in parallel)

Pillar 1: Empiric stress-dose glucocorticoid (FIRST)

Hydrocortisone 100 mg IV bolus, then 50–100 mg IV q6–8h.

Rationale: concomitant primary or central adrenal insufficiency may coexist; thyroid hormone increases cortisol clearance and can precipitate adrenal crisis. Once adrenal sufficiency is confirmed, taper and stop steroids.

Pillar 2: Thyroid hormone replacement

1. Preferred: IV levothyroxine (LT4) Loading dose 200–400 μg IV over first 24–48h; maintenance 50–100 μg IV daily once stable.
   • Reduce loading dose in elderly, history of CAD, arrhythmia, heart failure.
   • If IV formulation unavailable: crushed LT4 via nasogastric tube.
2. Adjunct liothyronine (LT3) – selective use only Reserved for profound shock, severe respiratory failure, or persistently low FT3 despite LT4. Low starting dose 5–20 μg IV loading, then 2.5–10 μg q8h; avoid in patients with active ischemia/arrhythmias. Consensus does not recommend routine combination LT4+LT3 for all patients.

Pillar 3: Supportive care & organ monitoring

1. Airway & ventilation: monitor PaCO₂; intubation/mechanical ventilation for hypercapnia, depressed GCS, laryngeal myxedema.
2. Rewarming: passive rewarming only (blankets), NO active rapid rewarming. Rapid rewarming causes vasodilation and refractory hypotension.
3. Fluid management: isotonic saline cautiously; restrict free water for hyponatremia. Avoid volume overload (pericardial effusion risk).
4. Glucose correction for hypoglycemia.
5. Cardiac continuous monitoring: watch for arrhythmia, worsening heart failure.
6. Search & treat precipitant: blood/urine cultures, chest imaging, empiric antibiotics if infection suspected.
7. Avoid all sedatives, opioids and drugs that slow metabolism.

4. Key Laboratory Monitoring

• Continuous cardiac monitoring; core temperature, BP, SpO₂, ABG.
• Sodium, creatinine, glucose, lactate every 6–12h early phase.
• TFT: repeat after 3–5 days, do not titrate dose based on early TSH. TSH may take weeks to normalize.
• Cortisol to guide steroid discontinuation.

5. Special Populations

1. Elderly/frail patients: lower LT4 loading dose, slower titration, more conservative rewarming. Atypical presentations often missed.
2. Central hypothyroidism: TSH may be normal/low; adrenal insufficiency must be ruled out before thyroid hormone.
3. Post-thyroidectomy patients: may have concurrent postoperative hypoparathyroidism (cross-reference 2026 Italian guideline for postoperative hypoparathyroidism); monitor calcium/PTH.
4. Pregnancy: rare; prioritize IV LT4, steroid coverage, high-risk obstetric + endocrine MDT.

6. Post-crisis Management & Discharge Planning

1. Once awake and gastrointestinal function recovered: switch IV LT4 to oral levothyroxine.
2. Identify root cause: Hashimoto, medication non-adherence, prior neck surgery.
3. Patient education: lifelong adherence, avoid precipitating medications, cold exposure.
4. Outpatient follow-up: TSH monitoring, long-term thyroid surveillance (compatible with KTA 2026 DTC guideline for thyroid cancer survivors).

7. Common Pitfalls

❌ Waiting for lab confirmation before starting therapy ❌ Active rapid rewarming ❌ Giving thyroid hormone before glucocorticoid (if adrenal insufficiency unexcluded) ❌ Overuse of LT3 in patients with coronary disease ❌ Overhydration, especially with hyponatremia and pericardial effusion ❌ Overinterpretation of early TSH as dose-adjustment marker

8. Evidence Gaps

1. No large RCTs; recommendations derived from registries, retrospective cohorts and expert consensus.
2. Optimal timing and dose of LT3 remain debated.
3. No standardized definition of myxedema coma, leading to variable reporting of incidence and mortality.
4. Limited real-world data for very old, multi-comorbid patients.

9. Cross alignment with prior guideline series

1. This ETA/BTA 2026 joint consensus (myxedema coma): paired with thyroid storm statement, covers the two major thyroid endocrine emergencies.
2. 2026 ETA immunoassay interference guideline: when TFT results look inconsistent with clinical picture, lab interference must be excluded.
3. 2026 Italian guideline for postoperative hypoparathyroidism: post-thyroidectomy patients may have concurrent hypoparathyroidism, requiring calcium/PTH monitoring.
4. KTA 2026 DTC follow-up guideline: patients after thyroidectomy on lifelong LT4 are at risk for crisis if therapy is interrupted.
5. NASIT 2026 thyroid embolization statement: thyroid intervention rarely can induce severe hypothyroidism in selected patients.

Disclaimer: This summary is for academic study only, not direct clinical practice. Myxedema coma is a life-threatening endocrine emergency requiring ICU and endocrinology multidisciplinary management.