Dihydrotachysterol (DHT) is a synthetic vitamin D analog developed in the early 20th century to help manage disorders of calcium metabolism, particularly hypocalcemia. Chemically derived from irradiated ergosterol and structurally related to vitamin D compounds, it differs from natural vitamin D in that it does not require renal activation, making it especially useful in patients with hypoparathyroidism or impaired kidney function. Its development followed the discovery of vitamin D’s role in preventing rickets in the 1920s, as researchers sought more controllable and rapidly acting alternatives; dihydrotachysterol emerged as a therapeutic agent that could raise blood calcium levels more predictably. By the mid-1900s, it was widely used for conditions such as hypoparathyroidism and certain forms of rickets, although its use has declined somewhat with the advent of newer active vitamin D analogs like calcitriol. Despite this, dihydrotachysterol remains historically significant as one of the earliest synthetic vitamin D derivatives used in clinical endocrinology.
