How are absorptive hypercalciuria types I and II differentiated?

Updated: Jun 02, 2021
  • Author: Stephen W Leslie, MD, FACS; Chief Editor: Vecihi Batuman, MD, FASN  more...
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The fasting and post–calcium-loading parameters are essentially the same in these 2 entities. The main difference is that patients with absorptive hypercalciuria type I still have hypercalciuria, defined as urinary excretion in excess of 200 mg of calcium per 24 hours, while on a 400-mg low-calcium diet. Patients with absorptive hypercalciuria type II have a less severe form of calcium hyperabsorption and are able to achieve normal urinary calcium levels while on the low-calcium diet.

Essentially, if the patient demonstrates normocalciuria on the restricted calcium diet, further testing is unnecessary because absorptive hypercalciuria type II is the only disorder that normalizes urinary calcium excretion on a limited oral calcium diet.

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