PTH and endothelial dysfunction: A deficiency of magnesium ions (Mg2+) in the blood, known as hypomagnesemia, may be a trigger for osteoporosis by the following pathways: (1) alter the structure of apatite crystals and affect bone cells; (2) reduce levels of parathyroid hormone (PTH) and lead to deficiency of vitamin D; (3) increase inflammatory cytokines and stimulate bone osteoporosis; (4) promote endothelial dysfunction.