Hyponatremia Management Algorithm

Algorithm Steps

1. ▶

   Start

   Serum Sodium <135 mEq/L

   Hyponatremia detected

   1. ◆

      Decision

      Severe Symptoms Present?

      Neurological emergency assessment

      • Severe: Seizures, obtundation, coma, respiratory arrest
      • Moderate: Nausea, confusion, headache, disorientation
      • Mild/Asymptomatic: Fatigue, gait disturbance, falls
      1. ⚠

         Warning

         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
         1. ●

            Action

            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)
            1. ◆

               Decision

               Hypotonic Hyponatremia?

               True dilutional hyponatremia

               1. ✓

                  Outcome

                  Non-Hypotonic

                  Treat underlying cause (hyperglycemia, pseudohyponatremia)

               2. ●

                  Action

                  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
                  1. ◆

                     Decision

                     Volume Status?

                     Guide etiology and treatment

                     1. ●

                        Action

                        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
                        1. ⚠

                           Warning

                           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
                           1. ●

                              Action

                              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
                              1. ✓

                                 Outcome

                                 Sodium Normalized

                                 Na+ >130 mEq/L, symptoms resolved

                              2. ✓

                                 Outcome

                                 Chronic Management

                                 Long-term cause treatment, periodic monitoring

                     2. ●

                        Action

                        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
                     3. ●

                        Action

                        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)