title: Dynamic changes in serum 25-hydroxyvitamin D during pregnancy and lack of effect on thyroid parameters.
abstract: OBJECTIVE
  To explore vitamin D status and its dynamic changes during pregnancy in women living in Northeast China. The association between 25-hydroxyvitamin D and serum calcium, phosphate and parathyroid hormone was studied. Because vitamin D deficiency or thyroid dysfunction/autoimmunity during pregnancy may lead to similar adverse events, the relationship between 25-hydroxyvitamin D and thyroid parameters was investigated.
  
  
  METHODS
  Serum samples of 50 women (aged 22 to 36 years) were selected retrospectively. The samples were collected at gestational 8 weeks ± 3 days, 20 weeks ± 3 days and 32 weeks ± 3 days for measurement of 25-hydroxyvitamin D, calcium, phosphate, parathyroid hormone, and thyroid parameters.
  
  
  RESULTS
  The median 25-hydroxyvitamin D levels were 28.29, 39.23 and 40.03 nmol/L, respectively, from the first to the third trimester. The 25-hydroxyvitamin D concentration during the first trimester was significantly lower than the next two trimesters (p<0.01) and was unchanged between the second and the third trimester. Of these women, 96%, 78% and 76% showed 25-hydroxyvitamin D ≤ 50 nmol/L during each trimester. Season was associated with 25-hydroxyvitamin D during each trimester (p<0.05), and a significant association was found between calcium and 25-hydroxyvitamin D during the first and the second trimesters. Only triiodothyronine was associated with 25-hydroxyvitamin D in the first trimester (p = 0.024), but statistical significance was only a trend (p = 0.063) after excluding abnormal values. No association was observed between 25-hydroxyvitamin D and phosphate, parathyroid hormone, and other thyroid parameters.
  
  
  CONCLUSIONS
  Vitamin D deficiency during pregnancy was prevalent in women from Northeast China who did not use supplementation. No significant relationships were observed between 25-hydroxyvitamin D and thyroid parameters during pregnancy.
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Yuhang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Miao
authors.affiliation: Department of Gynecology and Obstetrics, Shenyang Women's and Children's Hospital, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Chenyang
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Zhongyan
authors.initials: Z
authors.lastname: Shan
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Guan
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, People's Republic of China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Teng
mesh_terms: D000328:Adult; D002118:Calcium / Q000097:blood; D002681:China; D005260:Female; D006801:Humans; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood; D011262:Pregnancy Trimester, Second / Q000097:blood; D011263:Pregnancy Trimester, Third / Q000097:blood; D011264:Pregnancy Trimesters / Q000097:blood* / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium