Calcium levels are tightly regulated both extracellularly, where it plays a central role in bone formation and turnover, and intracellularly, given its numerous roles in intracellular signaling. Meeting adequate dietary calcium requirements is imperative (and varies by age) for maintaining adequate calcium homeostasis and optimizing bone health. However, there are numerous scenarios where dietary absorption and storage and/or other impacts on its network of hormone regulators (parathyroid hormone (PTH), calcitriol, calcitonin, and FGF23) can be impacted, causing various disturbances and resulting in either hypocalcemia or hypercalcemia.