From the Guidelines
For calcium supplementation, calcium carbonate is typically recommended at a dosage of 1,000-1,500 mg of elemental calcium daily, divided into 2-3 doses. This equates to approximately 2,500-3,750 mg of calcium carbonate since it contains 40% elemental calcium 1. Calcium carbonate should be taken with meals to enhance absorption, as it requires stomach acid for proper dissolution. For optimal absorption, individual doses should not exceed 500-600 mg of elemental calcium at one time, as the body can only absorb limited amounts at once. Patients should swallow tablets with a full glass of water and avoid taking calcium supplements within 1-2 hours of other medications, particularly antibiotics, thyroid medications, and certain blood pressure medications, as calcium may interfere with their absorption.
Key Considerations
- Side effects may include constipation, gas, or bloating, which can be minimized by starting with lower doses and gradually increasing 1.
- Calcium carbonate is preferred for most patients due to its higher elemental calcium content, lower cost, and convenience, though patients with low stomach acid (such as elderly individuals or those on acid reducers) may benefit from calcium citrate instead 1.
- The decision to use calcium supplements should consider the balance between potential benefits and harms, including the risk of cardiovascular disease 1.
- Dietary calcium intake should also be considered, as calcium-rich foods and beverages are the preferred sources of calcium 1.
Special Populations
- For patients with chronic kidney disease, the total calcium intake from diet, calcium-containing phosphate binders, and dialysate should not exceed 2 g/day 1.
- In dialysis patients, calcium supplementation should be limited to under 1,500 mg/day to avoid hypercalcemia and vascular calcification 1.
From the Research
Recommended Dosage and Administration of Calcium Carbonate
The recommended dosage and administration of calcium carbonate for patients requiring calcium supplementation vary depending on the patient's condition and the specific formulation of the calcium carbonate.
- For patients with chronic renal failure, a daily dose of 3 g of calcium carbonate has been shown to be effective in treating secondary hyperparathyroidism 2.
- For patients on hemodialysis, the required daily dose of calcium carbonate has been reported to be around 2.71 +/- 0.48 g, corresponding to 5.4 +/- 0.95 capsules of 500 mg, with an adjuvant daily aluminum hydroxide dose of 0.69 +/- 0.27 g 3.
- Calcium carbonate should be taken on an empty stomach, a few minutes before meals, to improve its absorption 3, 4.
Factors Affecting Calcium Carbonate Absorption
Several factors can affect the absorption of calcium carbonate, including:
- The presence of food in the stomach, which can enhance absorption 4
- The dose of calcium carbonate, with higher doses not necessarily leading to greater absorption 5
- The formulation of the calcium carbonate, with some preparations being more effective than others 6
Comparison with Other Calcium Supplements
Calcium carbonate has been compared to other calcium supplements, such as calcium citrate, in terms of absorption and efficacy.