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Urinary Disorders

Calcium Total 24 hr Urine

12/09/2010

Question:

I take 1800 mg calcium citrate on a daily basis because my parathyroids barely function. I also take .25mcg Calcitriol. How would this high calcium "diet" be expected to affect the total 24hr urine calcium levels? At a local lab, the standard range is: 35 - 250. Is any level over 250 considered a risk/danger for kidney stones, etc. even though the blood serum calcium levels are on the low side?

Answer:

Since you have a low blood calcium level (as expected in a patient with underactive parathyroids), the calcitriol and calcium supplements should merely result in bringing your calcium level up towards normal, and should not cause the urine calcium level to be high. Also, some of the calcium that you eat (as food and as tablets) will bind in the intestines with a food substance called oxalate. Oxalate is a component of many kidney stones, and if it binds to calcium in the intestines, it cannot be absorbed into the bloodstream and then go into the urine to cause trouble.

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University