What is the role of a calcium loading test in the traditional workup of hypercalciuria?

Updated: Jun 02, 2021
  • Author: Stephen W Leslie, MD, FACS; Chief Editor: Vecihi Batuman, MD, FASN  more...
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In the traditional diagnostic approach, a calcium-loading test is performed, with the type of hypercalciuria determined in the following ways:

  • Absorptive hypercalciuria - During a defined period of fasting, patients with absorptive hypercalciuria show a significant decrease in urinary calcium excretion; patients are then administered a large oral calcium meal, with urine samples obtained periodically afterwards tending to show a great increase in the patient’s urinary calcium excretion

  • Renal leak hypercalciuria – In this type, the kidney has an obligatory calcium-losing defect, so patients are expected to show relatively little effect from dietary measures alone, including fasting; following a large oral calcium meal, patients with renal leak hypercalciuria do not demonstrate as large an increase in urinary calcium as do those with absorptive hypercalciuria

In practice, however, performing the calcium-loading test is difficult, tedious, and usually reserved for selected cases in a tertiary care center or for research purposes.

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