VDR and rickets: There is no single effective treatment for fibromyalgia.[4] Whilst initially studied for its effects on bone health and calcium homeostasis, the global effects of vitamin D have recently become the focus of much research as vitamin D receptors (VDR) are increasingly found in multiple tissues.[5] The similarity in symptomatology of vitamin D deficiency (VDD) and chronic widespread pain has led researchers to investigate the relationship between hypovitaminosis D and fibromyalgia.