Calcium (Ca) and magnesium (Mg) are non-heavy metals with the same valence charge that are both critical for physiologic function, yet overlap each other in their mechanisms. For example, they both use the same transport systems in kidney competing with each other for absorption. They also oppose one another in blood coagulation, smooth muscle contraction and PTH release.
The relationship between Ca and Mg is important as it promotes a balance in given biological systems for proper function of the body. Deficiency either mineral could result in an improper balance leading to problems.