Electrolyte · Hyperkalemia treatment · Antidote
Calcium gluconate
Indications
- Acute symptomatic hypocalcemia, including citrate effects in massive transfusion or CRRT
- Hyperkalemia with ECG changes (off-label)
- Magnesium toxicity, as with preeclampsia infusions (off-label)
- Calcium channel blocker or beta-blocker poisoning (off-label)
- Hydrofluoric acid burns: gel, or local or intra-arterial infusion (off-label)
Dosing
| Where | Dose |
|---|---|
| Cardiac arrest | Calcium chloride: 1 g (10 mL of 10%) for hyperkalemia or calcium channel blocker overdose |
| Metabolic and electrolyte boluses | Calcium gluconate: 1–3 g IV over 2–5 min (stabilizes; repeat if ECG changes persist) |
| Metabolic and electrolyte boluses | Calcium chloride: 1 g via central line (three times the elemental calcium) |
| Unit conversions | Calcium (total): mg/dL ÷ 4 = mmol/L; ionized 1.1–1.3 mmol/L = 4.4–5.2 mg/dL |
| Unit conversions | Calcium gluconate 10%: 1 g = 4.65 mEq (93 mg) elemental calcium |
| Unit conversions | Calcium chloride 10%: 1 g = 13.6 mEq (272 mg) elemental calcium |
On the quick cards
Mechanism of action
Calcium gluconate dissociates in plasma, raising ionized Ca²⁺ with no liver step (label). Extracellular Ca²⁺ screens negative surface charges and shifts sodium channel gating, raising the threshold potential; this restores the gap that hyperkalemia's depolarized resting potential had narrowed, and with it conduction, without lowering potassium. A larger Ca²⁺ gradient also drives calcium through L-type channels a calcium channel blocker has left open, and Ca²⁺ antagonizes magnesium at the neuromuscular junction and heart.
Pharmacology
- Cardiovascular: reverses hyperkalemic ECG changes in about 3 min, for 30–60 min
- Cardiovascular: raises contractility and BP when ionized calcium is low; rapid injection causes hypotension, bradycardia and arrhythmias (label)
- Neuromuscular: ends tetany, laryngospasm and seizures; reverses magnesium-induced weakness and respiratory depression
- Hematologic: clotting needs Ca²⁺ (factor IV), so citrate-induced hypocalcemia impairs hemostasis
Pharmacokinetics
| Onset | 1–3 min IV |
|---|---|
| Duration | 30–60 min of membrane protection; ionized calcium starts falling again within 10 min of a bolus (Martin 1990) |
| Distribution | 99% of body calcium is in bone; serum calcium is about 50% ionized, 40% protein-bound and 8–10% complexed (label) |
| Protein binding | About 40%, mostly albumin; alkalosis increases binding and lowers ionized calcium |
| Metabolism | None; no liver step is needed (label), and it matched chloride in anhepatic patients (Martin 1990) |
| Elimination | Kidney filtration with PTH-regulated reabsorption; urinary calcium rises after a dose (label) |
| Equivalence | 30 mL of 10% gluconate ≈ 10 mL of 10% chloride (about 7 mmol) |
Chemistry
- Calcium D-gluconate (C₁₂H₂₂CaO₁₄, MW 430): two anions of gluconic acid, an oxidized glucose, per Ca²⁺
- 10% is 100 mg/mL with 9.3 mg (0.465 mEq) of elemental calcium per mL; 1 g gives 93 mg (4.65 mEq), a third of the chloride salt (label)
- Solubility is only about 3.3 g/100 mL (PubChem), so 10% is supersaturated and stabilized with calcium saccharate; warm cold vials to 60–80 °C to redissolve crystals (label)
- About 680 mOsm/L, a third of calcium chloride's, with pH 6.0–8.2 (label), so a secure peripheral IV is acceptable
- Contains aluminum (vials up to 512 mcg/L), a concern in kidney failure and premature infants (label)
Adverse effects and cautions
In the one-pagers
- Electrolyte ImbalancesHyperkalemia: stabilize, shift, remove: Stabilize (ECG changes): calcium gluconate 10% 30 mL over 10 min; in arrest or peri-arrest, calcium chloride 10% 10 mL over 5 min (same calcium). Acts in about 3 min, lasts 30–60 min; repeat if changes persist.
- BurnsElectrical and chemical burns: Hydrofluoric acid: pain out of proportion, often delayed. Calcium gluconate gel; watch calcium, magnesium, potassium and QT.
- Obstetric EmergenciesPreeclampsia and eclampsia: Magnesium toxicity: absent patellar reflexes, slow shallow breathing, drowsiness; oliguria raises levels. Stop the infusion, support breathing, give calcium gluconate 1 g IV (10 mL of 10%) over about 3 min.
- Pharmacology by Class and SuffixAntidotes and reversal: Magnesium sulfate: Calcium gluconate
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In the algorithms
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Sources
- FDA label: Calcium Gluconate (Fresenius Kabi, 2023)
- FDA label: Calcium Gluconate bulk bag (WG Critical Care, 2026)
- Martin 1990 (calcium salts without a liver)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.