Relation between the vitamin D status and the occurrence and severity of thyroid malignancy

Abstract

Background. In spite of large volume of data linking vitamin D with cardiovascular morbidity, autoimmunity, cancer, and virtually every organ system, vitamin D and thyroid is a lesser-known aspect of vitamin D in clinical practice. The association between vitamin D deficiency and thyroid cancer is controversial. Some studies have demonstrated that higher serum vitamin D levels might protect against thyroid cancer, whereas others have not, or have even indicated the opposite to to be the case. This review intends to highlight the current literature on the impact of vitamin D status on thyroid cancer. Materials and methods. References for this review were identified through searches of PubMed for articles published to from 2005 to June 2021 using the terms “thyroid cancer” and “vitamin D”. Results. A large volume of medical literature is available from observational studies linking vitamin D with thyroid cancer. Data from interventional studies documenting beneficial effects of vitamin D on thyroid autoimmunity is also available, but lesser than that from observational studies. Short-term high dose oral vitamin D supplementation reduces TPOAb titers. Certain vitamin D receptor (VDR) gene polymorphism have been linked to increased occurrence of autoimmune thyroid disorders. Vitamin D deficiency, decreased circulating calcitriol has been linked to increased thyroid cancer. Certain VDR gene polymorphisms have been linked with increased as well as decreased occurrence of thyroid cancer. Data is scant on use of vitamin D and its analogues for treating thyroid cancer. The results suggest that Vitamin D deficiency may have value as a negative prognostic indicator in papillary thyroid cancer and that pre-operative laboratory evaluation may be less useful. This is important because Vitamin D deficiency is modifiable. Conclusions. In spite of large volume of medical literature from observational studies linking vitamin D with thyroid cancer, meaningful concrete clinical data on impact of vitamin D supplementation on hard clinical end points in these disorders is lacking, and should be the primary area of research in the next decade.

Keywords

• thyroid cancer, 25-hydroxyvitamin d, vitamin d deficiency