Severe Hypocalcemia Management

Algorithm Steps

1. ▶

   Start

   Suspected Severe Hypocalcemia

   Corrected calcium <7.5 mg/dL (<1.9 mmol/L) or symptomatic

   1. ●

      Action

      Recognize Clinical Features

      Neuromuscular irritability predominates

      • Perioral/fingertip paresthesias
      • Tetany (carpopedal spasm, laryngospasm)
      • Chvostek sign: facial twitch on tapping
      • Trousseau sign: carpal spasm with BP cuff
      • Seizures
      • Prolonged QTc, arrhythmias
      • Hypotension, heart failure
      1. ◆

         Decision

         Severity Assessment

         Symptoms guide urgency

         • SEVERE/SYMPTOMATIC: Tetany, seizures, arrhythmias, laryngospasm
         • MODERATE: Paresthesias, muscle cramps, positive Chvostek/Trousseau
         • MILD/ASYMPTOMATIC: Incidental finding, Ca 7.5-8.0 mg/dL
         1. ●

            Action

            SEVERE: IV Calcium Replacement

            Emergency treatment

            • Calcium gluconate 10%: 1-2 ampules (10-20 mL) IV over 10 min
            • = 93-186 mg elemental calcium
            • Dilute in 50-100 mL D5W or NS
            • Cardiac monitoring during infusion
            • Then: Continuous infusion 1-2 mg/kg/hr elemental Ca
            1. ●

               Action

               Continuous Calcium Infusion

               After initial bolus for severe cases

               • Calcium gluconate: 10 ampules (100 mL) in 1L D5W
               • Infuse at 50-100 mL/hr (0.5-1 mg/kg/hr elemental)
               • Target: Corrected Ca 8.0-9.0 mg/dL
               • Do NOT add to bicarbonate-containing solutions
               • Peripheral line OK, but check for infiltration
               1. ●

                  Action

                  Identify Underlying Cause

                  Guide long-term management

                  • Post-thyroidectomy/parathyroidectomy: Transient or permanent hypoparathyroidism
                  • Vitamin D deficiency: Check 25-OH vitamin D
                  • Hypomagnesemia: Alcoholism, diuretics, malabsorption
                  • Chronic kidney disease: Check PTH, phosphorus
                  • Pancreatitis: Saponification of calcium
                  • Medications: Bisphosphonates, denosumab, cinacalcet
                  1. ⚠

                     Warning

                     ⚠️ Digoxin Caution

                     Risk of digoxin toxicity

                     • Calcium increases digoxin toxicity risk
                     • Slow calcium infusion if on digoxin
                     • Cardiac monitoring mandatory
                     • Consider lower infusion rates
                  2. ●

                     Action

                     Monitoring

                     Close follow-up during treatment

                     • Ionized or corrected calcium q4-6h
                     • Magnesium level
                     • Continuous ECG during IV infusion
                     • Phosphorus (avoid hypercalcemia if high phosphorus → calcification)
                     • Symptoms (paresthesias, tetany)
                     1. ●

                        Action

                        Transition to Oral Therapy

                        When calcium stable >8.0 mg/dL

                        • Oral calcium carbonate 1-3 g TID with meals
                        • Calcitriol 0.25-1 mcg/day (active vitamin D)
                        • Cholecalciferol if vitamin D deficient
                        • Overlap IV and oral before stopping IV
                        • Follow-up labs in 1-2 weeks
                        1. ✓

                           Outcome

                           Calcium Normalized

                           Continue oral supplements, address cause

                        2. ⚠

                           Warning

                           Chronic Hypoparathyroidism

                           Long-term management needed

                           • Lifelong calcium + calcitriol
                           • Target: Low-normal calcium (avoid hypercalciuria)
                           • Monitor for nephrocalcinosis/nephrolithiasis
                           • Consider PTH replacement (natpara) in refractory cases
            2. ●

               Action

               Check & Correct Magnesium

               CRITICAL: Hypocalcemia won't correct if Mg low

               • Mg <1.0 mg/dL: MgSO4 2g IV over 10-20 min, then infusion
               • Mg 1.0-1.5 mg/dL: MgSO4 1-2g IV over 1 hour
               • Oral: Mg oxide 400-800 mg daily
               • Hypomagnesemia causes PTH resistance
         2. ●

            Action

            MODERATE: IV/Oral Calcium

            Less urgent replacement

            • IV: Calcium gluconate infusion (slower rate)
            • OR Oral: Calcium carbonate 1-3 g TID with meals
            • Add calcitriol 0.25-0.5 mcg BID
            • Check and correct magnesium
         3. ●

            Action

            MILD: Oral Calcium + Vitamin D

            Outpatient management

            • Oral calcium 1-3 g/day in divided doses
            • Vitamin D or calcitriol
            • Recheck in 1-2 weeks
            • Identify underlying cause