What is the role of intestinal adaptation in the pathophysiology of hypercalciuria?

Updated: Jun 02, 2021
  • Author: Stephen W Leslie, MD, FACS; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Intestinal adaptation occurs with long-term, consistent calcium intake. This means that patients with persistently low dietary calcium increase their intestinal calcium absorption, and those with a high calcium intake show a corresponding decrease in intestinal absorption.

Fractional calcium absorption decreases with larger calcium loads, probably due to saturation of active absorption pathways. It plateaus at about 500 mg of calcium for most people. This means that an oral calcium dose is absorbed better if administered in small, divided portions rather than in a single large calcium bolus. In general, each additional 100 mg of daily dietary calcium ingestion increases urinary calcium levels by 8 mg/day in a healthy population but raises urinary calcium levels by 20 mg/day in hypercalciuric patients.

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