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Published on: March 29, 2020
Platelet function in cats with hyperthyroidism
Elizabeth C Hiebert1, David L Panciera1, Katie M Boes2
1Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.
Insights
Hyperthyroid cats did not show altered platelet function, measured by closure time, compared to healthy cats. However, hyperthyroid cats had a higher platelet count, suggesting further research into feline hypercoagulable states.
Area of Science:
- Veterinary Medicine
- Cardiovascular Physiology
- Hematology
Background:
- Hyperthyroidism in cats is associated with thromboembolic events.
- The role of platelet function in feline hyperthyroidism-related thromboembolism is not fully understood.
Purpose of the Study:
- To compare platelet function in hyperthyroid cats with age-matched euthyroid cats.
- To investigate if hyperthyroidism shortens collagen and adenosine diphosphate (C-ADP) closure times.
Main Methods:
- Platelet function was assessed using the platelet function analyzer (PFA-100) measuring C-ADP closure times.
- Platelet counts were also measured in 16 hyperthyroid and 9 euthyroid cats over 7 years of age.
Main Results:
- No significant difference in C-ADP closure times was observed between hyperthyroid and control cats.
- Hyperthyroid cats exhibited a significantly higher mean platelet count compared to controls.
- Treatment duration with methimazole did not significantly affect closure times.
Conclusions:
- Platelet function, under high shear conditions with C-ADP, is not affected by hyperthyroidism in this feline cohort.
- Further investigation is warranted to explore potential hypercoagulable states and the roles of platelets and von Willebrand factor in hyperthyroid cats.
Objectives:
Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls.
Methods:
Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism.
Results:
Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group (P = 0.023).
Conclusions And Relevance:
Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have.
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