Vitamin D: the underappreciated D-lightful hormone that is important for skeletal and cellular health

Vitamin D deficiency is more common than realized. It is making a resurgence in neonates and is common in black patients and older adults. Vitamin D deficiency not only causes generalized muscle weakness, muscle aches, and bone aches and pains but also can precipitate and exacerbate osteoporosis and cause osteomalacia. Although the kidney plays a critical role in producing 1,25-dihydroxyvitamin D, which is important for regulating calcium, phosphorus, and bone metabolism, it is now recognized that a wide variety of other tissues have the enzymatic machinery to produce 1,25-dihydroxyvitamin D. Vitamin D receptors are common in most tissues in the body, and the new revelation that many tissues produce 1,25-dihydroxyvitamin D suggests a new important role for this hormone in helping to maintain good health throughout life.