Interrelationships among Plasma 17-Hydroxycorticosteroid Levels, Plasma Protein-Bound Iodine Levels, and Ketosis in Dairy Cattle

Abstract

Ten ketotic cows and 10 normal cows, paired as to herd, breed, milk production level, time since parturition, and time of drawing and processing blood, were used in a study to relate adrenal-cortical and thyroid activity to the ketotic condition. Plasma level of 17-hydroxycorticosteroids was used as the index of adrenal-cortical activity, and thyroid activity was indicated by levels of plasma protein-bound iodine (PBI). Plasma 17-hydroxycorticosteroid values averaged 5.09 [mu]g% for the normal cows and 7.48 [mu]g% for the ketotic cows; whereas plasma PBI values were 4.22 [mu]g% and 2.58 [mu]g%, respectively, for the normal and ketotic cows. In both instances, differences between mean values were highly significant statistically (P 0.01). In another series of 11 ketotic cows (no paired control cows), the mean plasma 17-hydroxycorticosteroid values and the mean plasma PBI values were 7.03 [mu]g%, and 2.65 [mu]g%, respectively. It will be noted that in the ketotic cows high 17-hydroxycorticosteroid values were associated with low PBI values. This suggested that ketosis may be caused by a "relative" adrenal-cortical insufficiency induced by hypothyroidism.