From the Guidelines
For patients with calcium oxalate kidney stones, dietary calcium is preferred over supplemental calcium, and calcium citrate is the best form of calcium supplement to use, as it helps inhibit stone formation by binding to oxalate in the digestive tract. The recommended dosage is typically 200-400 mg of elemental calcium taken with meals, two to three times daily 1. Dietary calcium has been shown to reduce the risk of stone formation by binding to dietary oxalate in the gut, thereby reducing oxalate absorption and urinary excretion 1. In contrast, supplemental calcium may be associated with an increased risk of stone formation, particularly if taken between meals, as it may not effectively bind to dietary oxalate 1. Some key points to consider when using calcium supplements for calcium oxalate kidney stones include:
- Staying well-hydrated by drinking at least 2-3 liters of water daily to dilute stone-forming substances in urine 1
- Spreading calcium intake throughout the day with meals to maximize its binding capacity to dietary oxalate
- Limiting sodium intake to 100 mEq (2,300 mg) daily, as high sodium intake can increase urinary calcium excretion 1
- Consuming 1,000-1,200 mg per day of dietary calcium, as prospective observational studies consistently show an independent reduced risk of stone formation with higher dietary calcium intake 1. It's also important to note that certain beverages, such as alcoholic beverages, coffee, tea, wine, and orange juice, may be associated with a lower risk of stone formation, while sugar-sweetened beverages may demonstrate an increased risk 1. However, these beverages have not been evaluated in randomized trials, and their effects on stone formation are not fully understood. Overall, the best approach for managing calcium oxalate kidney stones is to focus on dietary changes, including increasing fluid intake, limiting sodium and animal protein, and consuming adequate dietary calcium, rather than relying on supplemental calcium 1.
From the FDA Drug Label
The changes induced by potassium citrate produce urine that is less conducive to the crystallization of stone-forming salts (calcium oxalate, calcium phosphate and uric acid). Increased citrate in the urine, by complexing with calcium, decreases calcium ion activity and thus the saturation of calcium oxalate Citrate also inhibits the spontaneous nucleation of calcium oxalate and calcium phosphate (brushite).
The best form of calcium when using for calcium oxalate kidney stones is calcium citrate.
- Calcium citrate is the preferred form of calcium because it can help increase urinary citrate levels, which can help prevent the formation of calcium oxalate stones.
- The use of calcium citrate can help decrease calcium ion activity and thus the saturation of calcium oxalate, making it less likely for stones to form 2.
From the Research
Forms of Calcium for Calcium Oxalate Kidney Stones
- The best form of calcium to use for preventing calcium oxalate kidney stones is not explicitly stated in the provided studies, but it can be inferred that calcium citrate may be beneficial 3.
- Calcium citrate can help increase urinary citrate levels, which can bind with calcium and inhibit the crystallization of calcium oxalate stones 3.
- Potassium citrate has also been shown to be effective in reducing urinary calcium excretion and increasing urinary citrate levels in patients with calcium oxalate stones and hypercalciuria 4.
Dietary Recommendations
- Moderate calcium intake, rather than restriction, may actually reduce the risk of calcium oxalate stone formation 5.
- Increasing calcium intake may reduce urinary oxalate excretion by binding more oxalate in the gut 6.
- Restricting dietary oxalate intake may also be beneficial in reducing the risk of calcium oxalate stone formation, especially in individuals with a high rate of oxalate absorption 6.
Treatment Options
- Potassium citrate and hydrochlorothiazide have been shown to be effective in reducing urinary calcium excretion in patients with calcium oxalate stones and hypercalciuria 4.
- Citrate salts, including potassium citrate and potassium-sodium citrate, have been shown to prevent new stone formation and reduce further stone growth in patients with residual stones that predominantly contain oxalate 3.