Background: The American Association of Clinical Endocrinologists (AACE) current recommendation is 1000-1200 mg calcium daily for postmenopausal and osteoporotic women. Some patients are reluctant to supplement calcium due to the fear of developing a kidney stone (nephrolithiasis). In the United States, every adult will have a 10% to 15% chance to get kidney stones in their lifetime. And the recurrence rate is up to 50% after 10 years. There is no clear theory on how kidney stones are formed. There are lots of factors that play into the role of kidney stone generation, such as urinary calcium, oxalate, citrate, phosphate, and pH levels. About 75% of kidney stones are calcium oxalate stones. And most patients with calcium oxalate stones are hypercalciuric and hyperoxaluric.Calcium supplements can increase calcium excretion in the urine, and in theory can increase the risk of calcium kidney stones. The purpose of this review is to find out if calcium supplementation does indeed increase risk of kidney stones in postmenopausal women.
Methods: An exhaustive search was conducted using Medline-OVID, Medline-PubMed, CINAHL, and Web of Science using the keywords: calcium supplementation, kidney calculi and postmenopausal women. Relevant articles were assessed for quality using GRADE.
Results: The initial search yielded 19 articles for review. After additional reading of the abstracts, two studies met inclusion criteria and were included in this systematic review. These articles include one randomized controlled trial and one observational study.
Conclusion: According to the results from the two studies and data collected, calcium supplementation in postmenopausal women does not increase the risk of calcium oxalate kidney stones. Also postmenopausal patients who had an incidence of kidney stones in the past should not be discouraged from taking calcium supplements to prevent them from having osteoporosis. Dietary and supplemental calcium intake in these studies seems to actually decrease the risk of kidney stone formation.
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