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endo.myxedema-coma.core.v1PRODUCTION
endo.myxedema-coma.core.v1

Myxedema coma

endocrinologyacuteadult
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Care setting:

Encounter flow

12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Recognize triad (AMS + hypothermia + precipitant) in hypothyroid patient; mortality 30-50% — empirical therapy without delay (ETA 2018 consensus; Wall JCEM 2000)

Inputs
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Actions
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Advance rule
Set
Advance when

myxedema coma suspected; treatment threshold crossed

Patient inputs (11)

Elderly women in winter — classic substrate; drug pharmacokinetics differ (Wall JCEM 2000; Mathew Thyroid 2011)

Bradycardia hallmark (ETA 2018 consensus)

Non-adherence is leading cause; surgical/RAI history suggests post-ablative substrate (Mathew Thyroid 2011)

Markedly elevated in primary; inappropriately low/normal in secondary (ATA 2014 Jonklaas)

Low FT4 confirms hypothyroidism severity (ATA 2014 Jonklaas)

Concomitant adrenal insufficiency common — give hydrocortisone BEFORE T4 (ETA 2018 consensus; ATA 2014)

Hyponatremia common (SIADH-like); slow correction (ETA 2018 consensus)

Hypoglycemia common (ETA 2018 consensus)

Hypothermia is hallmark; passive rewarming only — active risks vasodilation (ETA 2018 consensus)

Hypotension common; vasopressors poorly responsive without thyroid hormone (ETA 2018 consensus)

Amiodarone, lithium, IFN, TKIs cause hypothyroidism; opiates/sedatives precipitate (ETA 2018 consensus)

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Severity triggers (7)

7 need judgement
  • informationallife_threateningmyxedema_coma_suspected_no_steroid_yet
    AMS + hypothermia + severe hypothyroid lab pattern with no HC given (ETA 2018 consensus; ATA 2014)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningsevere_hyponatremia_lt_120_with_seizure
    Na <120 with seizure or coma (ETA 2018 consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateninghypercapnic_respiratory_failure
    pH <7.35 + PaCO2 >50 with depressed GCS (ETA 2018 consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverehypothermia_severe
    Core temp <32°C (ETA 2018 consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverehypoglycemia_in_myxedema
    Glucose <70 mg/dL (ETA 2018 consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverecardiac_decompensation_on_T3
    New arrhythmia or chest pain after T3 administration (ETA 2018 consensus; ATA 2014)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatedrug_induced_hypothyroidism
    Causative drug present (amiodarone, lithium, IFN, TKI) (ETA 2018 consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Myxedema coma — 5-pillar (steroid first → T4 ± T3 → warming → supportive → trigger)
axis: myxedema_coma_5pillarstep 1 - Pillar 1 — Hydrocortisone FIRST (cover concurrent AI)
Selected step "Pillar 1 — Hydrocortisone FIRST (cover concurrent AI)" — Myxedema coma suspected (AMS + hypothermia + severe hypothyroid pattern)
  • hydrocortisone
    first line
    glucocorticoid_short_acting
    100 mg IV bolus, then 100 mg IV q8h × 7 days then taper • IV • q8h
    triggers: myxedema_coma_suspected
    ATA 2014 + ETA 2020 — give BEFORE T4 to prevent precipitating adrenal crisis (T4 increases cortisol clearance); 50% have concurrent AI
    rxcui 5492

ed playbook — drug actions (6)

  1. 1. hydrocortisone IV
    100 mg IV bolus FIRST • IV • STAT
    trigger: Myxedema coma suspected
    Before T4 — prevents adrenal crisis (ETA 2018 consensus; ATA 2014)
  2. 2. levothyroxine IV
    200-400 mcg IV LOAD (100-200 mcg if elderly/CAD) • IV • load x 1
    trigger: After HC
    ETA 2018 consensus
  3. 3. liothyronine IV
    5-20 mcg IV bolus, then 2.5-10 mcg q8h • IV • q8h x 24-48h
    trigger: Severe coma
    Add active T3 (ETA 2018 consensus)
  4. 4. D50 if hypoglycemic
    25 g IV push • IV • PRN
    trigger: Glucose <70
    Common with concurrent AI (ETA 2018 consensus)
  5. 5. NS cautious
    250-500 mL over 1h then titrated • IV • continuous
    trigger: Hypotension
    Avoid overload (ETA 2018 consensus)
  6. 6. broad-spectrum antibiotics
    Per source • IV • per agent
    trigger: Suspected infection
    Infection #1 trigger (Mathew Thyroid 2011)

Auto-drafted A&P note

ed

Subjective

- Possible entry pathways: AMS + hypothermia + bradycardia (ETA 2018 consensus; Wall JCEM 2000); Core temperature <35 C (Mathew Thyroid 2011); TSH markedly elevated + FT4 low (ATA 2014 Jonklaas).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Myxedema coma** (endo.myxedema-coma.core.v1).
Phenotype framing: Phenotype: known hypothyroid decompensated, newly-diagnosed severe hypothyroidism, post-thyroidectomy/RAI, drug-induced (amio/lithium/IFN/TKI) (ETA 2018 consensus)
Scope: Recognize triad (AMS + hypothermia + precipitant) in hypothyroid patient; mortality 30-50% — empirical therapy without delay (ETA 2018 consensus; Wall JCEM 2000)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Myxedema coma — 5-pillar (steroid first → T4 ± T3 → warming → supportive → trigger)** — step "Pillar 1 — Hydrocortisone FIRST (cover concurrent AI)".
1. hydrocortisone 100 mg IV bolus, then 100 mg IV q8h × 7 days then taper IV q8h (glucocorticoid_short_acting, first line) — ATA 2014 + ETA 2020 — give BEFORE T4 to prevent precipitating adrenal crisis (T4 increases cortisol clearance); 50% have concurrent AI

Setting playbook (ed) — Recognize myxedema coma, give HC FIRST then T4, warm passively, transfer to ICU (ETA 2018 consensus; ATA 2014)
2. hydrocortisone IV 100 mg IV bolus FIRST IV STAT — Myxedema coma suspected (Before T4 — prevents adrenal crisis (ETA 2018 consensus; ATA 2014))
3. levothyroxine IV 200-400 mcg IV LOAD (100-200 mcg if elderly/CAD) IV load x 1 — After HC (ETA 2018 consensus)
4. liothyronine IV 5-20 mcg IV bolus, then 2.5-10 mcg q8h IV q8h x 24-48h — Severe coma (Add active T3 (ETA 2018 consensus))
5. D50 if hypoglycemic 25 g IV push IV PRN — Glucose <70 (Common with concurrent AI (ETA 2018 consensus))
6. NS cautious 250-500 mL over 1h then titrated IV continuous — Hypotension (Avoid overload (ETA 2018 consensus))
7. broad-spectrum antibiotics Per source IV per agent — Suspected infection (Infection #1 trigger (Mathew Thyroid 2011))

Non-pharmacologic actions:
- Passive rewarming with blankets (NO active external warming → vasodilation collapse) (ETA 2018 consensus)
- Cardiac monitor + IV access x 2 (ETA 2018 consensus)
- Foley + strict I/Os (ETA 2018 consensus)
- Airway support: low threshold for intubation if hypercapnic / GCS <8 (ETA 2018 consensus)
- Avoid sedatives/opioids (ETA 2018 consensus)

AVOID / contraindication checks:
- Never T4 before hydrocortisone (ETA 2018 consensus; ATA 2014)
- Passive rewarming only — no active external warming (ETA 2018 consensus)
- Cautious fluid resuscitation — avoid overload (ETA 2018 consensus)
- Correct Na <8 mEq per 24h (ETA 2018 consensus)
- Avoid sedatives and opioids (ETA 2018 consensus)
- Lower T4 dose in elderly and CAD (ETA 2018 consensus; ATA 2014)

Monitoring

Regimen monitoring:
- Continuous telemetry (ETA 2018 consensus)
- Core temp q1h (ETA 2018 consensus)
- q1-2h BP + GCS (ETA 2018 consensus)
- q4-6h BMP + glucose (ETA 2018 consensus)
- q24-48h TSH/FT4/FT3 (ATA 2014 Jonklaas)
- Daily ECG QTc (ETA 2018 consensus)
- Pulse oximetry continuous (ETA 2018 consensus)

Setting (ed) monitoring:
- Core temp q15 min (ETA 2018 consensus)
- BP + HR q15 min (ETA 2018 consensus)
- GCS q1h (ETA 2018 consensus)
- POC glucose q1h x 4h (ETA 2018 consensus)

Follow-up plan: Endo within 1 wk; titrate PO levothyroxine; education on adherence + sick-day continuation; address precipitant prevention; review medications causing hypothyroidism (ATA 2014 Jonklaas; NICE 2019)
- Close-out criterion: PO regimen + follow-up scheduled; adherence plan documented

Monitoring phase: Continuous telemetry, art line BP if unstable, core temp q1h, serial electrolytes + glucose q4-6h, TSH/FT4/FT3 q24-48h, neuro checks q2h, daily ECG (QT) (ETA 2018 consensus)

Disposition

Current setting: ed — Recognize myxedema coma, give HC FIRST then T4, warm passively, transfer to ICU (ETA 2018 consensus; ATA 2014)

Disposition criteria:
- ICU mandatory for all confirmed myxedema coma (ETA 2018 consensus)

Escalation triggers (move to higher acuity):
- Hypercapnic respiratory failure → intubate (ETA 2018 consensus)
- Refractory shock → ICU + pressors (ETA 2018 consensus)
- Severe hyponatremia <120 with seizures → 3% NaCl + ICU (ETA 2018 consensus)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] AMS + hypothermia + severe hypothyroid lab pattern with no HC given (ETA 2018 consensus; ATA 2014)
- [LIFE_THREATENING] Na <120 with seizure or coma (ETA 2018 consensus)
- [LIFE_THREATENING] pH <7.35 + PaCO2 >50 with depressed GCS (ETA 2018 consensus)

Citations

- 2014 ATA Hypothyroidism Guideline + 2020 ETA/BTA Myxedema Coma Consensus + 2024 ATA Position Statement on Severe Hypothyroidism + Popoveniuc 2014 score [PMID:25266247](https://pubmed.ncbi.nlm.nih.gov/25266247/)
- Cited evidence (PMID 24518183) [PMID:24518183](https://pubmed.ncbi.nlm.nih.gov/24518183/)

Last reconciled with current guidelines: 2026-05-22.
References
  • 2014 ATA Hypothyroidism Guideline + 2020 ETA/BTA Myxedema Coma Consensus + 2024 ATA Position Statement on Severe Hypothyroidism + Popoveniuc 2014 score — PMID:25266247
  • Cited evidence (PMID 24518183) — PMID:24518183