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Clin J Am Soc Nephrol. 2012 May;7(5):829-34. doi: 10.2215/CJN.11331111. Epub 2012 Mar 15.

Effect of vitamin D repletion on urinary calcium excretion among kidney stone formers.

Author information

1
Department of Medicine, Columbia University, New York, New York, USA. DELEAF@partners.org

Abstract

BACKGROUND AND OBJECTIVES:

Despite the important role of vitamin D in maintaining bone health, many clinicians are reluctant to treat vitamin D deficiency in kidney stone formers because of the theoretical risk of increasing urinary calcium excretion. This study examined the effect of vitamin D repletion on urinary calcium excretion among stone formers.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:

Participants (n=29) were recruited from urology clinics affiliated with New York Presbyterian Hospital. Enrollment criteria included a history of nephrolithiasis, urinary calcium excretion between 150 and 400 mg/d, and a serum 25-hydroxyvitamin D level <30 ng/ml. Participants were given oral ergocalciferol (50,000 IU/wk) for 8 weeks. Serum and 24-hour urine tests were repeated after 8 weeks.

RESULTS:

Levels of 25-hydroxyvitamin D increased significantly after vitamin D repletion (17±6 and 35±10 ng/ml, P<0.001), but mean 24-hour urinary calcium excretion did not change (257±54 and 255±88 mg/d at baseline and follow-up, respectively, P=0.91). However, 11 participants had an increase in urinary calcium excretion ≥20 mg/d; these participants also had an increase in urine sodium excretion, likely reflecting dietary variability. No participant experienced adverse effects from vitamin D, including hypercalcemia.

CONCLUSIONS:

Among stone formers with vitamin D deficiency, a limited course of vitamin D repletion does not seem to increase mean urinary calcium excretion, although a subset of individuals may have an increase. These data suggest that vitamin D therapy, if indicated, should not be withheld solely on the basis of stone disease, but 24-hour urinary calcium excretion should be monitored after repletion.

PMID:
22422535
DOI:
10.2215/CJN.11331111
[Indexed for MEDLINE]
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