What are the advantages of a calcium-loading test for the diagnosis of hypercalciuria?

Updated: Apr 23, 2019
  • Author: Stephen W Leslie, MD, FACS; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

The theoretical advantage of a formal calcium-loading test is a more precise diagnosis, which leads more quickly to definitive therapy. This is particularly useful in differentiating absorptive hypercalciuria type I and type II from renal leak hypercalciuria.

Usually, 2 separate 24-hour urine collections are gathered and analyzed for calcium while the patient is on a regular diet. This is undertaken to confirm the diagnosis of hypercalciuria, establish the baseline urinary calcium level, and determine if the degree of hypercalciuria is consistent and reproducible.

The patient is placed on a strict low-calcium diet of 400 mg of calcium and 100 mEq of sodium per day for 1 week. At the end of the week, an additional 24-hour urine sample is taken and tested for calcium and creatinine.


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