From the FDA Drug Label
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action Intravenous administration of calcium gluconate increases serum ionized calcium level. Calcium gluconate dissociates into ionized calcium in plasma. Ionized calcium and gluconate are normal constituents of body fluids.
The FDA drug label does not answer the question.
From the Research
Administering 1 gram of calcium gluconate intravenously will increase serum calcium levels by approximately 0.1-0.2 mmol/L (0.4-0.8 mg/dL). This modest increase occurs because calcium gluconate contains only about 90 mg of elemental calcium per gram (9% calcium by weight) 1. When administered, calcium gluconate dissociates in the bloodstream, releasing calcium ions that become available to increase serum levels. The effect is relatively short-lived, typically lasting 1-2 hours, as the body quickly begins to redistribute and excrete the additional calcium. For this reason, calcium gluconate is often given as a continuous infusion when sustained elevation of calcium levels is needed.
Some key points to consider:
- The actual increase in serum calcium may vary between patients depending on their body weight, kidney function, and baseline calcium status 2.
- In emergency situations such as severe hypocalcemia or cardiac arrest associated with hyperkalemia, multiple doses may be required to achieve the desired clinical effect 1.
- Calcium gluconate is preferred over calcium chloride for intravenous repletion of calcium deficiencies in the inpatient setting due to its lower irritancy to veins 3.
- The dose equivalence of calcium gluconate and calcium chloride should be carefully considered, with 10 mL of 10% calcium gluconate containing 2.2 mmol of calcium, equivalent to 4.4 mL of 7.35% calcium chloride or 2.2 mL of 14.7% calcium chloride 1.
Overall, the increase in serum calcium levels after administering 1 gram of calcium gluconate will depend on various factors, but a general estimate is an increase of 0.1-0.2 mmol/L (0.4-0.8 mg/dL), as supported by the most recent and highest quality study 1.