The Relation of Thyroid to the Conversion of Cyanides to Thiocyanate*

In 1932 Marine, Raumann, Spence, and Cipra (1) discovered that administration of cyanides to rabbits will usually lead to thyroid hyperplasia. As one phase of our study of the mechanism of this phenomenon we have investigated the fate of several cyanides given to normal and thyroidectomized rabbits with the results presented in this paper. Lang (2) first showed that 12 to 17 per cent of administered cyanide (KCN and CH&N) is detoxicated by conversion to thiocyanate and can be recovered from the urine as such. Hunt (3) also recovered considerable amounts of thiocyanate from the urine of guinea pigs injected with acetonitrile. Unfortunately his animals were fed on a diet containing cabbage, and we now know that the Crucifera contain large amounts of thiocyanate. Since this early work, the Rupp and Schied (4) method for estimating SCN has been chiefly used. While capable of yielding satisfactory determinations on pure solutions, we have found that this method gives results from 35 to 1000 per cent too high, when applied to urine and other animal matter. In the work reported here, the thiocyanate excretion of rabbits is used as a measure of cyanide metabolism and is determined by oxidation to HCN and estimation of the latter by the Liebig-DBniges method. With the amounts measured in these experiments, results correct within about 5 per cent are readily obtained. The