Review
Copyright ©The Author(s) 2021.
World J Diabetes. Sep 15, 2021; 12(9): 1363-1385
Published online Sep 15, 2021. doi: 10.4239/wjd.v12.i9.1363
Table 1 Vitamin D as a hormone: Comparison of the pituitary-thyroid and parathyroid hormone-vitamin D axes

Pituitary-thyroid axis
Parathyroid-vitamin D axis
Organ(s)Thyroid glandsSkin/liver/kidney
Source compoundIodine, tyrosineCholecalciferol (cholesterol), ergocalciferol
PrehormoneLevothyroxine, T1/2 = 6-7 d25-hydoxyvitamin D2/D3, T1/2 = 13-17 d
Active hormoneTriiodothyronine, T1/2 = 14-24 h1,25-dihydroxyvitamin D2/D3, T1/2 = 10-20 h
TransportationThyroxine binding globulinVitamin D binding protein
ReceptorThyroid hormone receptorVitamin D receptor
Stimulating factorThyroid stimulating hormoneParathyroid hormone
EffectEnergy homeostasisCalcium homeostasis