Calcium Intake and Urinary Stone Disease
Calcium homeostasis is a complicated and incompletely understood process that is primarily regulated through an interaction between the intestines, kidneys, and bones. Intestinal calcium absorption is determined by many factors including the amount of regular calcium intake, as well as vitamin D and parathyroid hormone levels. Intestinal calcium absorption is likely different between stone formers and non-stone formers, with higher levels of calcium absorption in those with a history of stones independent of their calcium intake. We no longer recommend dietary calcium restriction as this may lead to bone demineralization and an increase in stone formation. Practitioners need to continue to educate patients to maintain moderate dietary calcium intake. The effect of calcium supplementation on stone formation is currently controversial. It is likely that large doses of supplemental calcium, especially if taken separate from a meal, may lead to stone formation. When necessary, stone forming patients should be encouraged to take their calcium supplements with a meal and their stone disease should be monitored.
As 80–90% of kidney stones are composed of calcium in the form of either calcium oxalate or calcium phosphate, excess calcium excretion in the urine has been a primary focus in preventing stone recurrence. Calcium metabolism and calcium homeostasis are complex processes that involve multiple organ systems. A thorough understanding of the interaction between the various players in calcium homeostasis is critical to understanding the abnormalities and dysregulation that can arise when calcium is not managed appropriately by the intestines, vitamin D and parathyroid hormones, bones, and the kidneys. Calcium intake is perhaps one of the most misunderstood factors related to urinary stone formation and there is controversy as to whether there are differences in the effect of dietary and supplemental calcium on kidney stone formation.
Abstract and Introduction
Abstract
Calcium homeostasis is a complicated and incompletely understood process that is primarily regulated through an interaction between the intestines, kidneys, and bones. Intestinal calcium absorption is determined by many factors including the amount of regular calcium intake, as well as vitamin D and parathyroid hormone levels. Intestinal calcium absorption is likely different between stone formers and non-stone formers, with higher levels of calcium absorption in those with a history of stones independent of their calcium intake. We no longer recommend dietary calcium restriction as this may lead to bone demineralization and an increase in stone formation. Practitioners need to continue to educate patients to maintain moderate dietary calcium intake. The effect of calcium supplementation on stone formation is currently controversial. It is likely that large doses of supplemental calcium, especially if taken separate from a meal, may lead to stone formation. When necessary, stone forming patients should be encouraged to take their calcium supplements with a meal and their stone disease should be monitored.
Introduction
As 80–90% of kidney stones are composed of calcium in the form of either calcium oxalate or calcium phosphate, excess calcium excretion in the urine has been a primary focus in preventing stone recurrence. Calcium metabolism and calcium homeostasis are complex processes that involve multiple organ systems. A thorough understanding of the interaction between the various players in calcium homeostasis is critical to understanding the abnormalities and dysregulation that can arise when calcium is not managed appropriately by the intestines, vitamin D and parathyroid hormones, bones, and the kidneys. Calcium intake is perhaps one of the most misunderstood factors related to urinary stone formation and there is controversy as to whether there are differences in the effect of dietary and supplemental calcium on kidney stone formation.
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