[Calcium response to vitamin D supplementation]

Area of Science:

• Endocrinology
• Nephrology
• Nutritional Science

Background:

• Sufficient serum vitamin D levels are crucial for preventing chronic diseases.
• The impact of vitamin D supplementation on urine calcium excretion is debated.
• Many women have low vitamin D levels (deficiency or insufficiency).

Purpose of the Study:

• To assess urine calcium excretion in women with normal or high calcium levels after achieving vitamin D sufficiency.
• To compare the effects of different vitamin D supplementation regimens on calciuria.

Main Methods:

• Prospective interventional study involving 113 women (63 hypercalciuric, 50 normocalciuric).
• Baseline serum vitamin D and urine calcium excretion were measured.
• Participants received weekly vitamin D2/D3 or monthly vitamin D3 supplementation until serum levels reached ≥30 ng/ml.
• Urine calcium excretion was re-evaluated post-supplementation.

Main Results:

• Overall, no significant changes in urine calcium excretion were observed across all supplementation methods.
• Weekly supplementation led to increased urine calcium in 19% of hypercalciuric and 12% of normocalciuric women.
• Monthly high-dose supplementation increased urine calcium in 40% of hypercalciuric and 44% of hypercalciuric patients with renal lithiasis.

Conclusions:

• Vitamin D supplementation to achieve sufficiency is safe for most women.
• A subset of patients, especially those on monthly high-dose regimens, may experience significant calciuria increases.
• This increase in calciuria could elevate risks for kidney stones and bone loss in genetically predisposed individuals.