Endocrine Abstracts

Introduction: Vitamin D plays an important role in the regulation of the mother-placenta-fetus systemensuring normal growth, weight and development of the fetus, reducing the risks of gestational diabetes mellitus, eclampsia and preterm labor. There is insufficient data in the literature on the vitamin D metabolic pathways in pregnant women, and the available results require confirmation using more accurate methods of determination.

Objective: To study of vitamin D metabolism peculiarities in normal pregnancy in comparison with a control group of healthy female patients.

Methods: Two groups of patients participated in the study: group 1- pregnant patients (n=20) from 18 to 45 years of age with gestational age from week 9 to 13; group 2 - healthy female patients (n=19) who underwent blood sampling for vitamin D metabolites to determine total 25(OH)D by immunochemiluminescence assay and 25(OH)D3, 3-epi-25(OH)D3, 24,25(OH)2D3, 1,25(OH)2D3 by high-performance liquid chromatography with mass spectrometric detection (HPLC-MS/MS).

Results: In group 1, the following results were obtained: total 25(OH)D, 26.1 ng/ml [17.4; 37.3], 25(OH)D3, 25.6 ng/ml [17.4; 37.3], 3-epi-25(OH)D3, 1.8 ng/ml [1.1; 3.2], 1,25(OH)D3, 33.4 pg/ml [16.1; 46.0], 24,25(OH)D3, 0.8 ng/ml [0.4; 1.5]. In group 2: total 25(OH)D - 16.7 ng/ml [13.5; 27.2], 25(OH)D3 - 19.5 ng/ml [14.0; 27.0], 3-epi- 25(OH)D3 - 1.1 ng/ml [0.75; 1.47], 1,25(OH)D3 - 38.8 pg/ml [34.0; 46.4], 24,25(OH)D3 - 1.5 ng/ml [0.82; 2.69]. For the above parameters, statistically significantly higher levels in the pregnancy group were obtained for total 25(OH)D (P=0.02) and 3-epi-25(OH)D3 (P=0.002). The ratio of 1,25(OH)D3/25(OH)D3 metabolites, reflecting 1-alpha-hydroxylase activity, was 0.00132 ng/ml [0.00067; 0.00206] vs 0.0021 ng/ml [0.00153; 0.00264] (P=0.02); the 25(OH)D3/24,25(OH)D3 ratio reflecting 24-hydroxylase activity was 24.1 ng/ml [18.6; 60.7] vs 11.6 ng/ml [10.9; 17.6], P=0,003, and the 3-epi-25(OH)D3/25(OH)D3 ratio reflecting 3-epimerase activity, 0.08 ng/ml [0.07; 0.10] vs 0.05 ng/ml [0.05; 0.6], P=0.0004, for group 1 and group 2, respectively.

Conclusions: The data obtained indicate that in the first trimester of pregnancy the epimerization of vitamin D increases, which raises the levels of this metabolite in the blood. A decrease in activation and increase in deactivation of vitamin D in pregnant women was also observed, which reflects the ratios of metabolites that characterize these processes.