Serum Sodium <135 mEq/L
Hyponatremia detected
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NephrologyManagement
Hyponatremia Management Algorithm
Hyponatremia Management Algorithm: Serum Sodium <135 mEq/L → Severe Symptoms Present? → EMERGENT: Hypertonic Saline → Check Serum Osmolality → Hypotonic...
Pathway Overview
15 steps
Algorithm Steps
15 total
01Start 02Decision Severe Symptoms Present?
Neurological emergency assessment
- Severe: Seizures, obtundation, coma, respiratory arrest
- Moderate: Nausea, confusion, headache, disorientation
- Mild/Asymptomatic: Fatigue, gait disturbance, falls
03Warning EMERGENT: Hypertonic Saline
Immediate treatment for severe symptoms
- 3% NaCl 100-150 mL IV bolus over 10-20 min
- Can repeat x2 if symptoms persist
- Target: 4-6 mEq/L rise in first 1-2 hours
- Goal: Symptom improvement, NOT normalization
- Transfer to ICU for close monitoring
04Action Check Serum Osmolality
Classify by tonicity
- Hypotonic (<275 mOsm/kg): TRUE hyponatremia - continue workup
- Isotonic (275-295): Pseudohyponatremia (lipids, proteins)
- Hypertonic (>295): Translocational (hyperglycemia, mannitol)
05Decision Hypotonic Hyponatremia?
True dilutional hyponatremia
06Outcome Non-Hypotonic
Treat underlying cause (hyperglycemia, pseudohyponatremia)
07Action Assess Volume Status
Clinical examination + urine studies
- Hypovolemic: Orthostasis, tachycardia, dry mucosa, elevated BUN/Cr
- Euvolemic: No edema, normal BP/HR
- Hypervolemic: Edema, JVD, ascites, pulmonary congestion
- Check: Urine Na, Urine Osm, FENa
08Decision Volume Status?
Guide etiology and treatment
09Action Hypovolemic Hyponatremia
Volume resuscitation
- Causes: GI losses, diuretics, adrenal insufficiency
- Urine Na typically <20 mEq/L (renal compensation)
- Treatment: Isotonic saline (0.9% NaCl)
- Monitor for rapid autocorrection as volume restored
- Check cortisol if suspect adrenal insufficiency
10Warning Safe Correction Limits
CRITICAL: Avoid overcorrection → ODS risk
- Target: ≤8-10 mEq/L in first 24 hours
- High ODS risk (chronic, severe, malnourished): ≤6 mEq/L/24h
- If overcorrected: D5W infusion or desmopressin to re-lower
- Check Na+ q2-4h during active correction
11Action Monitor & Adjust
Serial sodium monitoring
- Check Na+ every 2-4 hours initially
- Watch for autocorrection (common in hypovolemic)
- Desmopressin 1-2 mcg IV/SC if overcorrecting
- Identify and treat underlying cause
12Outcome Sodium Normalized
Na+ >130 mEq/L, symptoms resolved
13Outcome Chronic Management
Long-term cause treatment, periodic monitoring
14Action Euvolemic Hyponatremia
Usually SIADH or related
- Causes: SIADH (most common), hypothyroidism, glucocorticoid deficiency
- SIADH criteria: Urine Osm >100, Urine Na >30, euvolemic, normal renal/adrenal/thyroid
- Treatment:
- - Fluid restriction (500-1000 mL/day) - first line
- - Oral urea 15-30g/day if FR fails
- - Tolvaptan 15mg daily if severe/refractory
- Path rejoins step 10Shared downstream outcome
15Action Hypervolemic Hyponatremia
Fluid overload states
- Causes: Heart failure, cirrhosis, nephrotic syndrome
- Treatment: Treat underlying cause
- - Fluid restriction
- - Loop diuretics
- - Salt restriction
- AVOID isotonic saline (worsens volume overload)
- Path rejoins step 10Shared downstream outcome
- Path rejoins step 04Shared downstream outcome
Guideline Source
Clinical practice guideline on diagnosis and treatment of hyponatraemia (ERA/ESE/ESICM)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Requires accurate serum and urine osmolality
- Volume status assessment can be challenging
- Does not address pediatric-specific management
- Overcorrection risks require close monitoring
Contraindicated Populations
neonates
Applicable Regions
EUUSglobal
EU: European ERA/ESE/ESICM guidelines
US: American guidelines align with European approach
Version 1Next review: 2027-01-01
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Frequently Asked Questions
What is the Hyponatremia Management Algorithm?
The Hyponatremia Management Algorithm is a management clinical algorithm for Nephrology. It provides a structured decision tree to guide clinical decision-making, based on Clinical practice guideline on diagnosis and treatment of hyponatraemia (ERA/ESE/ESICM).
What guideline is the Hyponatremia Management Algorithm based on?
This algorithm is based on Clinical practice guideline on diagnosis and treatment of hyponatraemia (ERA/ESE/ESICM) (DOI: 10.1093/ndt/gfu040).
What are the limitations of the Hyponatremia Management Algorithm?
Known limitations include: Requires accurate serum and urine osmolality; Volume status assessment can be challenging; Does not address pediatric-specific management; Overcorrection risks require close monitoring. Individual patient factors may require deviation from these recommendations.
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