Acute Hyponatremia Management - Hospitalist

Algorithm Steps

1. ▶

   Start

   Hyponatremia Detected

   Na+ <135 mEq/L

   1. ◆

      Decision

      Severity Assessment

      Symptoms and sodium level

      • SEVERE SYMPTOMS:
      • - Seizures, coma
      • - Severe confusion
      • - Respiratory distress
      • MODERATE SYMPTOMS:
      • - Nausea/vomiting
      • - Confusion, headache
      • MILD/ASYMPTOMATIC:
      • - Na 125-134 without symptoms
      1. ⚠

         Warning

         SEVERE: Immediate Treatment

         Symptomatic or Na+ <120

         • HYPERTONIC SALINE (3% NaCl):
         • - 100-150 mL IV over 10-20 min
         • - Goal: Raise Na+ by 4-6 mEq/L
         • - Can repeat x1-2 if still symptomatic
         • THEN slow down:
         • - Max 8-10 mEq/24h total correction
         • - Check Na+ q2h initially
         • ICU admission recommended
         1. ●

            Action

            Confirm True Hypotonic Hyponatremia

            Rule out pseudo- and non-hypotonic

            • CHECK SERUM OSMOLALITY:
            • Normal/High Osm (>280):
            • - Pseudohyponatremia (hyperlipidemia)
            • - Hyperglycemia (corrected Na = Na + 1.6×[(glu-100)/100])
            • - Mannitol
            • LOW Osm (<280) = TRUE HYPONATREMIA
            • - Proceed with workup
            1. ◆

               Decision

               Assess Volume Status

               Key to etiology and treatment

               • HYPOVOLEMIC: Dry mucosa, tachycardia, orthostatic
               • EUVOLEMIC: No edema, no signs of dehydration
               • HYPERVOLEMIC: Edema, JVD, ascites
               1. ●

                  Action

                  Hypovolemic Hyponatremia

                  Na+ and water loss, more Na+ than water

                  • CAUSES:
                  • - GI losses (vomiting, diarrhea)
                  • - Diuretics
                  • - Adrenal insufficiency
                  • - Salt-wasting nephropathy
                  • LABS: UNa usually <20 (renal conserving)
                  • TREATMENT:
                  • - Normal saline (0.9% NS)
                  • - Treat underlying cause
                  • - Hold diuretics
                  1. ⚠

                     Warning

                     CRITICAL: Correction Limits

                     Avoid osmotic demyelination syndrome

                     • MAX CORRECTION:
                     • - 8-10 mEq/L in first 24 hours
                     • - 8 mEq/L per 24h thereafter
                     • HIGH RISK FOR ODS:
                     • - Na+ <105 mEq/L
                     • - Hypokalemia
                     • - Alcoholism, malnutrition
                     • - Liver disease
                     • IF OVERCORRECTING:
                     • - Stop hypertonic/NS
                     • - Give D5W
                     • - Consider desmopressin (DDAVP)
                     1. ●

                        Action

                        Monitoring

                        Frequent reassessment

                        • SEVERE: Na+ q2h until stable
                        • MODERATE: Na+ q4-6h
                        • MILD: Na+ q12-24h
                        • Adjust treatment based on response
                        • Watch for overcorrection
                        • Check K+ (often low too)
                        1. ✓

                           Outcome

                           Goals

                           Safe correction

                           • Treat symptoms first
                           • Correct slowly (8-10 mEq/24h max)
                           • Address underlying cause
                           • Avoid ODS
                           • Target Na+ >130 mEq/L
               2. ●

                  Action

                  Euvolemic Hyponatremia

                  Most common inpatient

                  • CAUSES:
                  • - SIADH (most common)
                  • - Hypothyroidism
                  • - Adrenal insufficiency
                  • - Primary polydipsia
                  • - Reset osmostat
                  • SIADH CRITERIA:
                  • - Euvolemic, Serum Osm <280
                  • - Urine Osm >100, UNa >40
                  • - Normal thyroid/adrenal
                  • TREATMENT:
                  • - Fluid restriction (800-1500 mL/day)
                  • - Salt tablets ± loop diuretic
                  • - Tolvaptan (if refractory)
               3. ●

                  Action

                  Hypervolemic Hyponatremia

                  Total body water excess

                  • CAUSES:
                  • - CHF
                  • - Cirrhosis
                  • - Nephrotic syndrome
                  • - Kidney failure
                  • LABS: UNa usually <20
                  • TREATMENT:
                  • - Fluid AND sodium restriction
                  • - Diuretics (loop)
                  • - Treat underlying condition
                  • - Vaptans in select cases (CHF)