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symptom.hyponatremia-workup.v1

Hyponatremia symptom-triage (ED workup + cross-engine to syndrome)

symptomacutesubacuteundifferentiatedadultgeriatricacuteoutpatient
Start encounter →Print handoutPRODUCTION

Phase C shard-3-neuro-sym wave-11 expansion (2026-05-15) — pattern-matches symptom.diarrhea.ed.v1 (wave-10), symptom.cough.ed.v1 (wave-10), symptom.nausea_vomiting.ed.v1 (wave-10), symptom.weakness.ed.v1 (c1c2bc96 wave-9). Engine scope: ED triage + acuity (acute <48h vs chronic) + chronicity + volume-status (hypovolemic / euvolemic / hypervolemic) stratification + STAT 3% saline for severe symptomatic + cause workup (BMP + serum osm + urine osm + urine Na + TSH + cortisol). Companion to syndrome.hyponatremia.core.v1 which owns definitive correction algorithm + per-cause management. Bayesian linkage (LR+, LR−, T_treat, T_test, sodium thresholds, ODS risk thresholds) lives in companion depth bundle _briefs/symptom.hyponatremia-workup.v1.depth.md. 4 sibling-differentiation rows: parent (syndrome.hyponatremia.core.v1) + hypervolemic pivots (cardio.acute-hf.core.v1 + gi.cirrhosis.core.v1) + CSW (neuro.sah.core.v1). 8 severity triggers (≥6 per spec): acute_severe_symptomatic + over_correction_with_ods_risk + hypovolemic + hypervolemic_chf_cirrhosis + euvolemic_siadh + cerebral_salt_wasting_post_sah_tbi + adrenal_crisis + thiazide_mdma_exercise. KEY SAFETY RULES: STAT 3% saline for severe symptomatic regardless of acuity (seizure/coma/RR <8/AMS/vomiting); AVOID overcorrection >8-10 mEq/24h or >18 mEq/48h to prevent ODS / central pontine myelinolysis; high-ODS risk = premenopausal women + alcoholic + malnourished + hypokalemic + severe Na <115; REVERSE overcorrection with D5W + DDAVP; CSW vs SIADH distinction is critical (uric acid + volume status); AVOID tolvaptan in cirrhosis (FDA boxed warning); STAT hydrocortisone empiric for adrenal crisis (do not wait for cortisol). Calculators wired (0): Adrogue-Madias / sodium correction calculator — schema-blocked; ticketed in shard-3 state file. Panels wired: panel.cbc + panel.renal + panel.lft + panel.thyroid + panel.inflammation. Schema-blocked: workup.hyponatremia / workup.serum_osmolality / workup.urine_studies_hypona / calc.adrogue_madias / calc.sodium_correction — NOT in clinical-tools-registry; manual application in setting playbook required_assessments + ticketed in shard-3 state file. Regimen_axes intentionally empty — engine is triage-only. Detailed drug ladder (3% NaCl, NS, fluid restrict, urea, tolvaptan, D5W+DDAVP rescue, hydrocortisone, levothyroxine, fludrocortisone, lorazepam, mannitol, discontinue offending med) lives in setting_playbooks.ed.drug_actions; definitive treatment is owned by syndrome.hyponatremia.core.v1. Setting playbooks: ED (primary) + outpatient (chronic mild follow-up + deprescribing + cause workup). SCAFFOLDED status: no workup.hyponatremia in clinical-tools-registry; PRODUCTION audit would fail. Will promote once registry entries land.

Entry points (15)

  • lab_abnormality
    Na <120 + seizure / coma / severe AMS — acute severe symptomatic hyponatremia; STAT 3% saline 100 mL IV bolus × 3 q10 min until sx improvement; AVOID overcorrection >8-10 mEq/24h to prevent ODS (Verbalis 2014 PMID 24484567)
    acute_severe_hyponatremia_seizure_or_coma
  • lab_abnormality
    Chronic Na 125-134 + asymptomatic — outpatient workup; cause stratification (medication, hypothyroid, adrenal, SIADH, hypervolemic, hypovolemic, reset osmostat); slow correction to prevent ODS
    chronic_asymptomatic_hyponatremia
  • symptom
    Na <135 + orthostatic / dry mucosa / decreased turgor / GI losses (V/D, diuretic, hemorrhage) / renal losses (CSW) — hypovolemic hyponatremia; IVF NS 1-2 L bolus → replace volume; recheck Na + correction trajectory
    hypovolemic_hyponatremia
  • symptom
    Na <135 + edema + JVD + ascites + chronic disease — hypervolemic hyponatremia (CHF, cirrhosis, nephrotic); fluid restriction 800-1000 mL/d + diuretic ± tolvaptan (caution cirrhosis) → route cardio.acute-hf.core.v1 / gi.cirrhosis.core.v1
    hypervolemic_hyponatremia_chf_cirrhosis_nephrotic
  • symptom
    Na <135 + euvolemic + urine osm >100 + urine Na >40 — SIADH (medication, malignancy, CNS, pulmonary, postoperative); fluid restriction 800-1000 mL/d ± urea ± tolvaptan ± salt tabs + furosemide (workup cause)
    euvolemic_siadh
  • symptom
    Chronic mild hyponatremia (Na 125-130) + stable + no sx + chronic illness (TB, malignancy, psychiatric, malnutrition, pregnancy) — reset osmostat; no specific tx beyond addressing cause
    reset_osmostat
  • symptom
    Hyponatremia + psychiatric hx + excessive water intake + urine osm <100 (max dilution) — psychogenic polydipsia; fluid restriction + psychiatric eval; resolve with restriction
    psychogenic_polydipsia
  • symptom
    Post-SAH / TBI + hyponatremia + hypovolemic (orthostatic, hemoconcentration) + urine Na >40 — CSW (distinct from SIADH); requires VOLUME REPLACEMENT (NS or 3% saline) — opposite of SIADH; consider fludrocortisone; route neuro.sah.core.v1 (PMID 27797307)
    cerebral_salt_wasting
  • symptom
    Hyponatremia + heavy alcohol use + low dietary solute intake — beer potomania / tea-and-toast; urine osm appropriately dilute (<200) but limited solute clearance; nutrition + solute repletion
    beer_potomania_low_solute
  • symptom
    Hyponatremia + recent thiazide (HCTZ, chlorthalidone) initiation / dose increase — thiazide-induced; discontinue thiazide; replete volume; consider alternative antihypertensive
    thiazide_induced_hyponatremia
  • symptom
    Hyponatremia + MDMA (ecstasy) OR endurance event (marathon, ultra) + excessive water intake during exertion — exercise-associated; restriction + 3% saline if symptomatic; ICU monitoring for cerebral edema
    mdma_endurance_exercise_hyponatremia
  • symptom
    Hyponatremia + hypothyroid features (cold, bradycardia, AMS, hypothermia, non-pitting edema, severe TSH elevation) — severe hypothyroidism / myxedema; route endo.myxedema-coma.core.v1; levothyroxine + cortisol + supportive
    hypothyroid_severe_hyponatremia
  • symptom
    Hyponatremia + hyperkalemia + hypotension + steroid history OR Addison features — adrenal insufficiency; STAT hydrocortisone 100 mg IV (empiric) + fluids; route endo.adrenal-crisis.core.v1
    adrenal_insufficiency_hyponatremia
  • lab_abnormality
    Apparent hyponatremia + hyperglycemia (correct Na 2.4 mEq per 100 mg/dL glucose >100) OR hyperlipidemia / paraproteinemia — pseudohyponatremia; corrected Na may be normal; do not aggressively correct
    pseudohyponatremia_hyperglycemia_or_lipid
  • lab_abnormality
    Na ≤120 + seizure / coma / RR <8 / cerebral herniation features — life-threatening; STAT 3% saline + ICU + neuroprotection + treat seizure (lorazepam)
    severe_hyponatremia_with_seizure_threshold

Required inputs (29)

  • agerequired
    demographic • used at CONTEXT
    Age shifts priors: elderly → thiazide / SIADH / hypovolemic from GI losses + medication; young adult → MDMA / psychogenic polydipsia / exercise / adrenal; pediatric → CSW post-meningitis (Verbalis PMID 24484567)
  • sexrequired
    demographic • used at CONTEXT
    Premenopausal female + post-op hyponatremia → high ODS / cerebral edema risk (lower osmotic threshold); pregnancy → physiologic dilutional
  • serum_sodium_valuerequired
    lab • used at FRAME
    Severity by Na: severe ≤120, moderate 121-129, mild 130-134 — drives 3% saline indication + monitoring intensity (Verbalis PMID 24484567)
  • acuity_chronicity_durationrequired
    symptom • used at FRAME
    Acute (<48 h) → tolerant to faster correction (cerebral edema risk dominates); chronic (>48 h or unknown) → SLOW correction (max 8-10 mEq/24h) to prevent ODS / central pontine myelinolysis (Sterns NEJM PMID 30207998)
  • neuro_symptoms_severityrequired
    symptom • used at ENTRY
    Severe sx (seizure, coma, AMS, vomiting, RR <8) → STAT 3% saline regardless of acuity; moderate sx (headache, nausea, confusion) → cautious 3% saline if severe Na; asymptomatic → cause workup
  • volume_status_assessmentrequired
    symptom • used at ENTRY
    Hypovolemic (orthostatic, dry mucosa, decreased turgor, JVD flat, hemoconcentration) → IVF NS; euvolemic (no edema, no orthostatic) → SIADH workup; hypervolemic (edema, JVD, ascites) → fluid restrict + diuretic
  • medications_thiazide_ssri_carbamazepine_chemo_desmopressinrequired
    history • used at CONTEXT
    Thiazide (HCTZ, chlorthalidone), SSRI (especially elderly), carbamazepine, oxcarbazepine, MDMA, chemotherapy (cyclophosphamide, vincristine), desmopressin, NSAIDs → drug-induced; discontinue or substitute
  • heart_failure_cirrhosis_nephrotic_historyrequired
    history • used at CONTEXT
    CHF / cirrhosis / nephrotic syndrome → hypervolemic hyponatremia; fluid restrict + diuretic; route cardio.acute-hf.core.v1 / gi.cirrhosis.core.v1; AVOID over-correction
  • malignancy_small_cell_lung_cancer
    history • used at CONTEXT
    Small-cell lung cancer + head/neck cancer + lymphoma + bladder + GI malignancy → SIADH ectopic ADH production; CT chest / imaging workup
  • cns_pathology_sah_tbi_stroke_meningitis
    history • used at CONTEXT
    SAH / TBI / stroke / meningitis / abscess → SIADH OR CSW (distinguish — volume status critical); CSW → volume replacement; SIADH → fluid restrict (Sterns CSW PMID 27797307)
  • pulmonary_pathology_pneumonia_tuberculosis
    history • used at CONTEXT
    Pneumonia / TB / abscess / COPD with hypoxia → SIADH; resolve with pulmonary tx
  • endocrine_hypothyroid_adrenalrequired
    history • used at CONTEXT
    Hypothyroidism (myxedema) + adrenal insufficiency (Addison) → endocrine hyponatremia; cortisol + TSH + ACTH stim; STAT hydrocortisone if adrenal crisis suspected (Spasovski PMID 25411137)
  • psychiatric_or_polydipsia_history
    history • used at CONTEXT
    Psychiatric (schizophrenia, bipolar) + excessive water intake → psychogenic polydipsia; urine osm <100 (max dilution); restriction
  • exertional_event_marathon_mdma
    history • used at CONTEXT
    Endurance event / MDMA + excessive water intake → exercise-associated / MDMA-related; 3% saline if symptomatic + ICU; high cerebral edema risk
  • sbprequired
    vital • used at CONTEXT
    Hypotension + hyponatremia → adrenal crisis OR severe hypovolemia OR sepsis; STAT IVF + hydrocortisone empiric if adrenal suspected
  • hrrequired
    vital • used at CONTEXT
    Tachycardia → volume depletion / sepsis; bradycardia → hypothyroid
  • rrrequired
    vital • used at CONTEXT
    Bradypnea (RR <8) → severe hyponatremia with cerebral edema / brainstem compromise → STAT 3% saline + airway
  • temp
    vital • used at CONTEXT
    Hypothermia → hypothyroid / adrenal; fever → infection / SIADH from CNS / pulm infection
  • bmp_full_panelrequired
    lab • used at INITIAL_WORKUP
    Na (confirm), K (hyperK + Na low → adrenal), Cl, HCO3 (anion gap), BUN/Cr (volume status, AKI), glucose (pseudohypona correction), Ca, Mg, PO4
  • serum_osmolalityrequired
    lab • used at INITIAL_WORKUP
    Serum osm <275 → true hypotonic hyponatremia; isotonic (280-295) → pseudohyponatremia (hyperlipidemia, paraproteinemia); hypertonic (>295) → hyperglycemia, mannitol, glycine (TURP) — different management
  • urine_osmolalityrequired
    lab • used at INITIAL_WORKUP
    Urine osm <100 → primary polydipsia / beer potomania / reset osmostat (max dilution); urine osm >100 → SIADH / hypovolemic / hypervolemic / endocrine (Verbalis 2014 PMID 24484567)
  • urine_sodiumrequired
    lab • used at INITIAL_WORKUP
    Urine Na <20 → hypovolemic (extrarenal losses), hypervolemic (CHF/cirrhosis); urine Na >40 → SIADH, CSW, adrenal, thiazide, renal salt-wasting
  • tsh_t4_free_cortisol_acthrequired
    lab • used at INITIAL_WORKUP
    TSH + free T4 → hypothyroid; AM cortisol + ACTH stim → adrenal insufficiency; both endocrine causes correctable with replacement
  • lft_albumin
    lab • used at INITIAL_WORKUP
    Albumin (cirrhosis, malnutrition), LFT (cirrhosis); albumin <30 → suspect malnutrition / cirrhosis / nephrotic
  • uric_acid_serum
    lab • used at BRANCHING_WORKUP
    Uric acid <4 in SIADH (low due to dilution); uric acid normal/high in CSW + hypovolemic — helpful adjunct to distinguish CSW from SIADH
  • glucose_serumrequired
    lab • used at INITIAL_WORKUP
    Glucose >200 → corrected Na (add 2.4 mEq/L per 100 mg/dL above 100); pseudohyponatremia must be corrected before treatment
  • lipid_panel_protein
    lab • used at BRANCHING_WORKUP
    Severe hyperlipidemia / paraproteinemia → pseudohyponatremia on standard ion-selective electrode (less common with direct ISE)
  • chest_xray_or_ct
    imaging • used at BRANCHING_WORKUP
    CXR / CT chest — pneumonia, TB, small-cell lung cancer (SIADH cause); empyema; abscess
  • ct_head_or_mri_if_neurosx
    imaging • used at BRANCHING_WORKUP
    CT head / MRI — SAH, TBI, stroke, abscess, mass (SIADH or CSW cause); CT before LP for meningitis if AMS

12-phase flow (12)

  1. 1FRAME
    Sodium severity (severe ≤120 / moderate 121-129 / mild 130-134); acuity (acute <48 h vs chronic >48 h or unknown); chronicity drives correction rate (acute → tolerant; chronic → SLOW max 8-10 mEq/24h to prevent ODS) (Verbalis PMID 24484567; Sterns PMID 30207998)
    inputs: serum_sodium_value, acuity_chronicity_duration
    advance: severity + acuity stratified
  2. 2ENTRY
    Neurologic severity (seizure / coma / AMS / vomiting / RR <8 → STAT 3% saline; moderate sx → cautious 3% saline; asymptomatic → workup); volume status (hypovolemic / euvolemic / hypervolemic) — drives initial fluid strategy
    inputs: neuro_symptoms_severity, volume_status_assessment
    advance: symptom severity + volume status determined
  3. 3CONTEXT
    Age + sex + vitals + temp; medication review (thiazide, SSRI, carbamazepine, MDMA, cyclophosphamide, desmopressin, NSAIDs); HF / cirrhosis / nephrotic history; malignancy (SCLC SIADH); CNS pathology (SAH/TBI/stroke/meningitis — SIADH vs CSW); pulmonary (pneumonia/TB SIADH); endocrine (hypothyroid, adrenal); psychiatric polydipsia; exertional (marathon, MDMA)
    inputs: age, sex, sbp, hr, rr, temp, medications_thiazide_ssri_carbamazepine_chemo_desmopressin, heart_failure_cirrhosis_nephrotic_history, malignancy_small_cell_lung_cancer, cns_pathology_sah_tbi_stroke_meningitis, pulmonary_pathology_pneumonia_tuberculosis, endocrine_hypothyroid_adrenal, psychiatric_or_polydipsia_history, exertional_event_marathon_mdma
    advance: context complete
  4. 4RED_FLAGS
    Acute severe symptomatic hyponatremia (Na <120 + seizure / coma / RR <8 / cerebral herniation features) → STAT 3% saline 100 mL IV bolus × 3 q10 min until sx improvement; over-correction risk (>8-10 mEq/24h → ODS / central pontine myelinolysis) — premenopausal women + alcoholic + malnourished + hypokalemic at higher ODS risk
    inputs: serum_sodium_value, neuro_symptoms_severity, rr
    advance: no immediate life-threat OR 3% saline + ICU activated
  5. 5INITIAL_WORKUP
    BMP (Na confirmed, K, BUN/Cr, glucose for pseudo correction); serum osmolality (true hypotonic vs pseudo); urine osmolality (max dilution <100 in polydipsia/potomania; high in SIADH/hypovolemic/hypervolemic); urine Na (extrarenal vs renal); TSH + cortisol + ACTH stim (endocrine); LFT + albumin; uric acid (low in SIADH); lipid panel + protein (pseudo correction)
    inputs: bmp_full_panel, serum_osmolality, urine_osmolality, urine_sodium, tsh_t4_free_cortisol_acth, glucose_serum, lft_albumin, uric_acid_serum, lipid_panel_protein
    actions: panel.cbc, panel.renal, panel.lft, panel.thyroid
    advance: cause stratification possible
  6. 6BRANCHING_WORKUP
    Hypovolemic + urine Na <20 → extrarenal (GI, sweat); urine Na >40 → renal (diuretic, salt-wasting, CSW). Euvolemic + urine osm >100 + urine Na >40 → SIADH (workup CNS, pulm, malig, drugs). Hypervolemic + edema → CHF (route cardio.acute-hf.core.v1), cirrhosis (route gi.cirrhosis.core.v1), nephrotic. Endocrine → TSH + cortisol; psychiatric → polydipsia. CXR / CT chest for malignancy or pneumonia; CT/MRI head for CNS
    inputs: chest_xray_or_ct, ct_head_or_mri_if_neurosx
    advance: definitive cause identified or routed to syndrome engine
  7. 7DIFFERENTIAL
    Hypovolemic: GI losses (V/D), renal (diuretic, mineralocorticoid def, salt-wasting), sweat. Euvolemic: SIADH (CNS, pulm, malig, drug, postop), hypothyroid, adrenal, reset osmostat, primary polydipsia, beer potomania. Hypervolemic: CHF, cirrhosis, nephrotic, advanced CKD. Pseudo: hyperglycemia, hyperlipidemia, paraproteinemia. Special: CSW (post-SAH/TBI), exercise-associated, MDMA, thiazide.
    advance: cause ranked
  8. 8RISK_STRATIFICATION
    Severity by Na (≤120 severe), neuro sx (seizure/coma/vomiting), acuity (acute → faster correction tolerable; chronic → slower); ODS risk factors (premenopausal female, alcoholic, malnourished, hypokalemic, severe Na <115); CHF/cirrhosis volume status
    advance: risk stratification documented
  9. 9TREATMENT
    STAT 3% saline 100 mL IV bolus × 3 q10 min if severe sx (seizure/coma/AMS/vomiting/RR <8) regardless of acuity. Acute (<48h) or severe sx → faster correction tolerated; chronic (>48h or unknown) → SLOW max 8-10 mEq/24h to prevent ODS (Sterns PMID 30207998; Hoorn PMID 20009108). Hypovolemic → NS 1-2 L bolus + cause workup. Euvolemic SIADH → fluid restrict 800-1000 mL/d ± urea ± tolvaptan ± salt + furosemide. Hypervolemic → fluid restrict + diuretic ± tolvaptan (caution cirrhosis). CSW → volume replacement NS / 3% saline + fludrocortisone (route neuro.sah.core.v1). Hypothyroid → levothyroxine (route endo.myxedema-coma.core.v1). Adrenal → hydrocortisone 100 mg IV STAT (route endo.adrenal-crisis.core.v1). Reverse over-correction with D5W + desmopressin if Na rise >8-10 mEq/24h. Stop offending drugs.
    inputs: serum_sodium_value, neuro_symptoms_severity, volume_status_assessment
    advance: definitive treatment initiated or routed
  10. 10DISPOSITION
    Discharge: chronic asymptomatic mild hyponatremia (Na >130) on outpatient workup; corrected pseudohyponatremia; psychogenic polydipsia with fluid restriction. Observation: moderate sx + Na 125-129 responding to NS + workup. Ward: most hyponatremia requiring IV correction + monitoring. Telemetry: severe symptomatic on 3% saline + Na q2-4h. ICU: severe symptomatic (seizure, coma, RR <8); cerebral edema; CHF/cirrhosis decompensated; ODS / over-correction. Route to: syndrome.hyponatremia.core.v1 (definitive algorithm); cardio.acute-hf.core.v1; gi.cirrhosis.core.v1; neuro.sah.core.v1 (CSW); endo.myxedema-coma.core.v1; endo.adrenal-crisis.core.v1.
    advance: disposition assigned + downstream handoff complete
  11. 11MONITORING
    Na q2-4h during 3% saline (target rise 4-6 mEq/L in 6 h then plateau); BMP q4-6h until stable; correction trajectory (max 8-10 mEq/24h; reverse with D5W + DDAVP if exceeded); seizure recurrence; neuro exam q1h while severe; volume status reassessment q2-4h; ICU-level if severe sx
    inputs: serum_sodium_value, neuro_symptoms_severity
    advance: Na trajectory controlled + sx improved
  12. 12FOLLOWUP
    Outpatient endocrinology if SIADH / hypothyroid / adrenal; nephrology if CKD / CSW / refractory; oncology if SIADH-paraneoplastic; cardiology / hepatology if hypervolemic; psychiatric if polydipsia; deprescribing thiazide / SSRI / carbamazepine if drug-induced; fluid restrict education; sodium intake counseling; recurrence prevention
    advance: long-term plan in place + follow-up scheduled