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syndrome.hyponatremia.core.v1PRODUCTION
syndrome.hyponatremia.core.v1

Hyponatremia (syndrome aggregator)

nephrologyacutesyndromeadult
Hard-required inputs
0 / 8
Care setting:

Encounter flow

12/12 authored

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

Current phase

Frame

Detailed

Confirm hypotonic hyponatremia: tonicity assessment first to rule out pseudo + translocational (Spasovski 2014 ESC — Algorithm 1 step 1)

Inputs
3
Actions
1
Advance rule
Set
Advance when

Hypotonic confirmed (Spasovski 2014 ESC)

Patient inputs (12)

Elderly + women + premenopausal women at higher ODS risk (Sterns NEJM 2015)

Pseudohyponatremia from hyperglycemia — Hillier corrected sodium formula in this runtime (Spasovski 2014 ESC)

Hypovolemic / euvolemic / hypervolemic branches treatment (Spasovski 2014 ESC — Algorithm 1)

Thiazides, SSRIs, desmopressin, MDMA, NSAIDs as drivers (Verbalis AJM 2013; Spasovski 2014 ESC)

Severity tier and correction ceiling calculation (Spasovski 2014 ESC)

Tonicity classification: hypotonic <275 vs isotonic vs hypertonic (Spasovski 2014 ESC)

High UOsm → ADH-driven (SIAD/HF/cirrhosis); low → primary polydipsia/low-solute diet (Verbalis AJM 2013; Spasovski 2014 ESC)

UNa <20 → hypovolemic; UNa >40 → SIAD/CSW/diuretic (Verbalis AJM 2013; Spasovski 2014 ESC)

Hypervolemic subtype; tolvaptan contraindicated (FDA boxed warning; Schrier NEJM 2006 SALT)

Hypervolemic subtype; tolvaptan candidacy (Schrier NEJM 2006 SALT-1/2)

Hypothyroidism rare cause of euvolemic hyponatremia (Spasovski 2014 ESC — exclude before diagnosing SIAD)

Adrenal insufficiency rare but reversible cause (Spasovski 2014 ESC — exclude before diagnosing SIAD)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (8)

8 need judgement
  • informationallife_threateningsevere_symptomatic_hypoNa — Spasovski 2014
    Seizure / coma / severe AMS regardless of Na value (Spasovski 2014 ESC)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverena_under_120_with_symptoms — Spasovski 2014
    Na <120 + headache, nausea, gait disturbance (Spasovski 2014 ESC — moderately symptomatic)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereovercorrection_risk — Spasovski 2014
    Na rise >10 mmol/L in 24h OR >0.5 mmol/L/hour (Sterns NEJM 2015)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereods_high_risk_pt — Spasovski 2014
    Chronic Na <105 OR alcoholism OR malnutrition OR liver disease OR hypokalemia (Sterns NEJM 2015)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereexercise_associated_hyponatremia — Spasovski 2014
    Marathon / endurance event + new AMS or seizure + Na <130 + hypotonic fluid intake history (2015 International Exercise-Associated Hyponatremia Consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveretolvaptan_LFT_alert — Spasovski 2014
    AST/ALT >3x ULN on tolvaptan (FDA boxed warning; Schrier NEJM 2006 SALT)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatecsw_vs_siad_ambiguity — Spasovski 2014
    CNS injury (SAH, TBI, meningitis, post-neurosurgery) + hyponatremia + UNa >40 — distinguish CSW (volume-depleted, FEurate >11% after Na correction, often hypotensive / postural / negative balance) vs SIAD (euvolemic, FEurate <11%, normal-to-positive balance — Maesaka 2009; Sterns NEJM 2015)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatebeer_potomania_or_low_solute_pattern — Spasovski 2014
    Chronic alcohol use OR low-solute diet (tea-and-toast in elderly) + hyponatremia + Uosm <100 + low protein/Na intake (Sterns NEJM 2015)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

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TREATMENTrequiredDrives dose adjustment
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Recommended regimen

Tonicity-volume-driven correction (Spasovski 2014 ESC; Verbalis AJM 2013)
axis: hyponatremia_tonicity_volume_treestep severe_symptomatic - Severe symptomatic (seizure / coma / AMS) — STAT 3% NaCl (Spasovski 2014 ESC)
Selected step "Severe symptomatic (seizure / coma / AMS) — STAT 3% NaCl (Spasovski 2014 ESC)" — severe-symptomatic phenotype: seizure / coma / AMS regardless of Na level OR Na <120 with severe symptoms (Spasovski 2014 ESC — recommendation 6.3.1)
  • hypertonic_saline_3pct
    first line
    hypertonic_saline
    100-150 mL IV bolus over 10-20 min • IV • repeat × 2 if symptoms persist (max 3 boluses)
    triggers: severe_symptoms, Na<120
    Spasovski 2014 ESC — bolus increases Na by 2-3 mmol/L per bolus; aim for 4-6 mmol/L total acute rise
    rxcui 9863

ed playbook — drug actions (4)

  1. 1. 3% NaCl bolus
    100-150 mL IV over 10-20 min • IV • repeat × 2 if symptoms persist (max 3)
    trigger: Severe symptoms (seizure/coma/AMS) (Spasovski 2014 ESC)
    Spasovski 2014 ESC — 4-6 mmol/L acute rise reverses cerebral edema
  2. 2. normal saline
    500-1000 mL IV • IV • titrate
    trigger: Hypovolemic + asymptomatic (Spasovski 2014 ESC)
    Volume restoration suppresses ADH (Spasovski 2014 ESC; Verbalis AJM 2013)
  3. 3. fluid restriction
    <800-1000 mL/day • PO • continuous
    trigger: Euvolemic SIAD (Verbalis AJM 2013)
    Spasovski 2014 ESC first-line
  4. 4. DDAVP clamp + D5W
    DDAVP 2-4 mcg IV/SC + D5W 6 mL/kg • IV/SC • as needed
    trigger: Over-correction risk (Na rising >0.5/h or already up >8 in 24h) (Sterns NEJM 2015)
    ODS prevention; reverse trajectory (Sterns NEJM 2015)

Auto-drafted A&P note

ed

Subjective

- Possible entry pathways: Serum Na <135 mmol/L mild / <130 moderate / <125 severe (Spasovski 2014 ESC severity tiers); Altered mental status / seizure / coma (Spasovski 2014 ESC — severely symptomatic); Headache, nausea, vomiting (Spasovski 2014 ESC — moderately symptomatic).

Objective

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

Assessment

**Hyponatremia (syndrome aggregator)** (syndrome.hyponatremia.core.v1).
Phenotype framing: Pseudo / translocational / hypovolemic (GI, diuretic, salt-wasting, CSW) / euvolemic (SIAD, hypothyroid, AI, primary polydipsia, beer potomania, exercise, MDMA) / hypervolemic (HF, cirrhosis, nephrotic, advanced CKD) (Spasovski 2014 ESC — Algorithm 1; Verbalis AJM 2013)
Scope: Confirm hypotonic hyponatremia: tonicity assessment first to rule out pseudo + translocational (Spasovski 2014 ESC — Algorithm 1 step 1)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Tonicity-volume-driven correction (Spasovski 2014 ESC; Verbalis AJM 2013)** — step "Severe symptomatic (seizure / coma / AMS) — STAT 3% NaCl (Spasovski 2014 ESC)".
1. hypertonic_saline_3pct 100-150 mL IV bolus over 10-20 min IV repeat × 2 if symptoms persist (max 3 boluses) (hypertonic_saline, first line) — Spasovski 2014 ESC — bolus increases Na by 2-3 mmol/L per bolus; aim for 4-6 mmol/L total acute rise

Setting playbook (ed) — Identify severe symptoms requiring 3% NaCl, classify by tonicity-volume tree, prevent overcorrection (Spasovski 2014 ESC — Algorithm 1)
2. 3% NaCl bolus 100-150 mL IV over 10-20 min IV repeat × 2 if symptoms persist (max 3) — Severe symptoms (seizure/coma/AMS) (Spasovski 2014 ESC) (Spasovski 2014 ESC — 4-6 mmol/L acute rise reverses cerebral edema)
3. normal saline 500-1000 mL IV IV titrate — Hypovolemic + asymptomatic (Spasovski 2014 ESC) (Volume restoration suppresses ADH (Spasovski 2014 ESC; Verbalis AJM 2013))
4. fluid restriction <800-1000 mL/day PO continuous — Euvolemic SIAD (Verbalis AJM 2013) (Spasovski 2014 ESC first-line)
5. DDAVP clamp + D5W DDAVP 2-4 mcg IV/SC + D5W 6 mL/kg IV/SC as needed — Over-correction risk (Na rising >0.5/h or already up >8 in 24h) (Sterns NEJM 2015) (ODS prevention; reverse trajectory (Sterns NEJM 2015))

Non-pharmacologic actions:
- Frequent Na monitoring (q2h while on 3%) (Spasovski 2014 ESC)
- Identify and treat trigger (drug, hormonal, water excess) (Verbalis AJM 2013)
- STAT nephrology consult if Na <120 + symptoms (Spasovski 2014 ESC)
- ICU/HDU bed for 3% NaCl infusion (Spasovski 2014 ESC)

AVOID / contraindication checks:
- Tolvaptan block if liver disease (FDA boxed warning; Schrier NEJM 2006 SALT — hepatotoxicity)
- Tolvaptan inpatient only and lt 30d (FDA label; Spasovski 2014 ESC)
- Fluid restriction caution if cirrhosis (Spasovski 2014 ESC — risk of renal impairment)
- Max correction 8 10 per 24h or 6 if ods risk (Sterns NEJM 2015; Spasovski 2014 ESC)
- Ddavp clamp if overcorrection (Sterns NEJM 2015 — ODS prevention)

Monitoring

Regimen monitoring:
- Na q2h while 3pct running (Spasovski 2014 ESC)
- Na q4-6h while titrating (Spasovski 2014 ESC; Verbalis AJM 2013)
- Na q6-12h after stable (Spasovski 2014 ESC)
- LFTs baseline and monthly on tolvaptan (FDA boxed warning; Schrier NEJM 2006 SALT)

Setting (ed) monitoring:
- Na q2h while on 3% NaCl (Spasovski 2014 ESC)
- Na q4-6h while titrating (Spasovski 2014 ESC)
- Hourly UOP (Verbalis AJM 2013)
- Mental status reassessment (Sterns NEJM 2015)

Follow-up plan: Address cause (med review, HF/cirrhosis treatment); educate on fluid intake; outpatient BMP (Verbalis AJM 2013; Spasovski 2014 ESC)
- Close-out criterion: Follow-up scheduled (Verbalis AJM 2013; Spasovski 2014 ESC)

Monitoring phase: Na q2h while titrating then q4–6h; correction ceiling ≤10 mmol/24h (≤8 if high-risk); DDAVP clamp + D5W if overcorrecting (Spasovski 2014 ESC; Sterns NEJM 2015)

Disposition

Current setting: ed — Identify severe symptoms requiring 3% NaCl, classify by tonicity-volume tree, prevent overcorrection (Spasovski 2014 ESC — Algorithm 1)

Disposition criteria:
- Discharge: Na >130 + asymptomatic + cause identified + outpatient follow-up arranged (Verbalis AJM 2013)
- Admit ward: Na 120-130 + needing fluid restriction + workup (Spasovski 2014 ESC)
- Admit ICU: Na <120 + symptoms or 3% running (Spasovski 2014 ESC)

Escalation triggers (move to higher acuity):
- Persistent seizures despite 3 boluses → ICU + continuous 3% + airway (Spasovski 2014 ESC)
- Over-correction trajectory → DDAVP + D5W (Sterns NEJM 2015 — ODS prevention)
- Na <115 → ICU regardless of symptoms (Spasovski 2014 ESC)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Seizure / coma / severe AMS regardless of Na value (Spasovski 2014 ESC)
- [SEVERE] Na <120 + headache, nausea, gait disturbance (Spasovski 2014 ESC — moderately symptomatic)
- [SEVERE] Na rise >10 mmol/L in 24h OR >0.5 mmol/L/hour (Sterns NEJM 2015)

Citations

- European Clinical Practice Guideline on Hyponatraemia 2014 (ESE/ESICM/ERA-EDTA) + Endocrine Society 2013 Expert Panel + US Expert Panel 2013 + 2015 International Exercise-Associated Hyponatremia Consensus + Sterns NEJM 2015 review [PMID:24569125](https://pubmed.ncbi.nlm.nih.gov/24569125/)
- Cited evidence (PMID 24138591) [PMID:24138591](https://pubmed.ncbi.nlm.nih.gov/24138591/)
- Cited evidence (PMID 24065153) [PMID:24065153](https://pubmed.ncbi.nlm.nih.gov/24065153/)
- Cited evidence (PMID 17105757) [PMID:17105757](https://pubmed.ncbi.nlm.nih.gov/17105757/)
- Cited evidence (PMID 10824078) [PMID:10824078](https://pubmed.ncbi.nlm.nih.gov/10824078/)

Last reconciled with current guidelines: 2026-05-12.
References
  • European Clinical Practice Guideline on Hyponatraemia 2014 (ESE/ESICM/ERA-EDTA) + Endocrine Society 2013 Expert Panel + US Expert Panel 2013 + 2015 International Exercise-Associated Hyponatremia Consensus + Sterns NEJM 2015 review — PMID:24569125
  • Cited evidence (PMID 24138591) — PMID:24138591
  • Cited evidence (PMID 24065153) — PMID:24065153
  • Cited evidence (PMID 17105757) — PMID:17105757
  • Cited evidence (PMID 10824078) — PMID:10824078