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February 13, 1943


JAMA. 1943;121(7):518. doi:10.1001/jama.1943.02840070046016

Among the products derived from ergosterol on irradiation are two compounds with closely similar structure, calciferol and tachysterol. The former, known as vitamin D2 in the European literature, is known here, when dissolved in oil, as viosterol. About twelve years ago the suggestion was made that the toxic effects of overdosage with irradiated ergosterol were due to something other than vitamin D; an active calcifying factor was discovered which would not cure rickets. This substance was identified as a dihydrotachysterol, a derivative of tachysterol. This substance, known also as A. T. 10, has the property of increasing the level of serum calcium and also of causing a definite urinary excretion of phosphorus, properties which suggested its use in human parathyroid tetany, with highly favorable results.1

The early claims that dihydrotachysterol was ineffective in curing rickets were reinvestigated by Shohl and his co-workers,2 who concluded that it is