Vitamin B12 and Vitamin D Levels in Patients with Autoimmune Hypothyroidism and Their Correlation with Anti-Thyroid Peroxidase Antibodies

Med Princ Pract. 2020;29(4):364-370. doi: 10.1159/000505094. Epub 2019 Nov 29.


Background: This study was designed to investigate the vitamin D (vit-D) and vitamin B12 (vit-B12) levels and their correlation with anti-thyroid peroxidase (anti-TPO) antibodies in patients with autoimmune hypothyroidism.

Methods: A total of 130 patients diagnosed with autoimmune hypothyroidism were included in the study retrospectively. The patients were divided into two groups as those having vit-B12 levels below 200 pg/mL (n = 60) and vit-B12 levels equal to or above 200 pg/mL (n = 70). These two groups were compared in terms of age, sex, thyroid-stimulating hormone (TSH), free-T4 (FT4), vit-D, and anti-TPO. The correlation between vit-B12 and anti-TPO levels was also investigated in these groups. Patients were then divided into four groups according to their vit-D levels. Patients with normal vit-D levels (25[OH]D >30 ng/mL; n = 5), those with vit-D insufficiency (20-30 mg/mL; n = 9), those with vit-D deficiency (10-20 ng/mL; n = 43), and those with severe vit-D deficiency (<10 ng/mL; n = 73). These four groups were compared in terms of age, gender, TSH, FT4, vit-B12, and anti-TPO levels. In addition, the correlation between levels of vit-D and anti-TPO was also investigated.

Results: We found that vit-B12 deficiency and vit-D deficiency were associated with autoimmune hypothyroidism, and that there was a negative correlation between vit-B12 and vit-D levels and anti-TPO antibodies in these patients.

Conclusion: In patients with autoimmune hypothyroidism, vit-D and vit-B12 deficiency should be investigated at the time of diagnosis and periodically on follow-ups.

Keywords: Anti-thyroid peroxidase antibodies; Autoimmune hypothyroidism; Vitamin B12; Vitamin D.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Female
  • Hashimoto Disease / blood*
  • Hashimoto Disease / complications*
  • Humans
  • Iodide Peroxidase / blood*
  • Male
  • Middle Aged
  • Retrospective Studies
  • Thyroiditis, Autoimmune / blood*
  • Thyroiditis, Autoimmune / complications*
  • Thyrotropin / blood
  • Vitamin B 12 / blood*
  • Vitamin B 12 Deficiency / blood
  • Vitamin B 12 Deficiency / complications*
  • Vitamin D / blood*
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / complications*
  • Vitamins / blood
  • Young Adult


  • Vitamins
  • Vitamin D
  • Thyrotropin
  • Iodide Peroxidase
  • Vitamin B 12

Supplementary concepts

  • Hypothyroidism, Autoimmune