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

Abstract

Summary Ten ketotic cows and ten 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. Plasma 17-hydroxycorticosteroid values averaged 5.09 μ g. % for the normal cows and 7.48 μ g. % for the ketotic cows; whereas plasma protein-bound iodine values were 4.22 μ g. % and 2.58 μ g. %, respectively, for the normal and ketotic cows. In both instances, differences between mean values were highly significant statistically (P μ g. %, and 2.65 μ g. %, respectively. It will be noted that in the ketotic cows high 17-hydroxycorticosteroid values were associated with low protein-bound iodine values. This suggested that ketosis may be caused by a relative adrenal-cortical insufficiency induced by hypothyroidism.