Stepien, RL, Rapoport GS, Henik RA, Sartor LL, Wenholz L: Effect of measurement method on blood pressure findings in cats before and after therapy for hyperthyroidism. Journal of Veterinary Internal Medicine 17: 754, 2003.

Abstract presented at the 13th ECVIM-CA Congress.

Elevated blood pressure (BP) is reported to occur in the majority of cats with hyperthyroidism but measurement method and patient temperament or level of anxiety ("white coat effect") may alter blood pressure findings. The purpose of this study was to document the effect of different measurement methods on blood pressure findings in cats with hyperthyroidism before and after treatment. BP was measured by one of three measurement methods in hyperthyroid cats prior to therapy for hyperthyroidism. Group 1 (n=84) cats had Doppler BP measurements obtained under controlled conditions by a single trained operator, Group 2 (n=13) cats had oscillometric systolic BP measurements (tail cuff) obtained under controlled conditions with a single trained operator and Group 3 (n=27) cats had Doppler BP measurements obtained in a busy clinic environment by operators with varying amounts of training. For all statistical analyses, a p value of <0.05 was considered significant.

Median [interquartile range] BP in Group 1 cats with untreated hyperthyroidism was significantly lower (140[131-153] mmHg) than that of Group 2 cats (163[152-170] mmHg) and Group 3 cats (160 [150-171] mmHg). Median BP values for Groups 2 and 3 did not differ. 19% of group 1 cats had BP measurements > 160 mmHg, a significantly lower proportion than noted in Group 2 (62%) and Group 3 cats (56%).

Blood pressure measurements were obtained 30-60 days post-therapy for a number of cats in each group (Group 1, n=23, Group 2, n=13, Group 3, n=10). When compared to pretreatment values for the same cats, post-therapy average BP, median BP and mean difference in individual BP did not differ significantly among groups.

We conclude that the method of measurement may affect BP results in hyperthyroid cats and that within the Doppler method, BP values obtained in a controlled environment by a trained operator are significantly lower than values obtained in a less controlled situation. Blood pressure methodologies used in this small study did not detect a significant change in BP in response to therapy for hyperthyroidism.