Endocrine Abstracts

Introduction

Vitamin D deficiency is considered as a major public health concern. Due to vitamin D’s crucial role in the intestinal calcium absorption, its deficiency may result in hypocalcemia and in a spectrum of associated clinical manifestations.

Aim

To assess the effect of 25(OH) vitamin D level (25(OH)D) on the frequency of hypocalcemia episodes and the daily profile of serum calcium and 24-h urinary calcium levels.

Methods

The interventional, prospective, comparative study of 10 healthy volunteers (women/men – 9/1) was performed. We have analyzed the daily profiles of serum calcium (total (Ca_total) and albumin-corrected calcium (Ca_corr)) and 24-h urinary Ca levels. The descriptive statistics are represented by medians and the first and third quartiles in Me (Q1; Q3) and by absolute and relative frequencies.

Results

Episodes of hypocalcemia were registered in patients with low vitamin D levels: in 3.33% for Ca_total and in 5.8% for Ca_corr. No clinical symptoms was observed. The frequency of hypocalcemia decreased to 0% for Ca_total and to 2.5% for Ca_corr after vitamin D supplementation, while we did not detect any difference in Me serum Ca and 24-h urinary Ca levels. However, the summary number of reference calcium values increased as 25(OH)D level was reached more than 30 ng/ml: from 90.8 to 100% for Ca_total and from 94.2 to 97.5% for Ca_corr. Analysis of Ca_total and Ca_corr deviations during the day showed a less variability of the calcium profile after vitamin D treatment. This study also revealed circadian character of daily serum calcium profile with the presence of maximum (0940–1740) and minimum (2340–0740) values during the day.

Conclusion

Target 25(OH)D levels more than 30 ng/ml are needed for effective calcium absorption. We confirmed the decreased frequency of hypocalcemia and the less variability of serum calcium levels during the day, as well as an increased number of reference calcium values after vitamin D supplementation.