Platelet function in cats with hyperthyroidism

Abstract

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.

Assessment of hemostasis in hyperthyroid and euthyroid cats using two viscoelastic assays and platelet aggregometry

“…With respect to WBPIA, the hyperthyroid cats in our study did not appear to have a significant increase in platelet aggregability based on MaxA. These results are in concordance with a recent study using the PFA100 which did not document a difference in platelet function between hyperthyroid and euthyroid cats 18 . Our study does have some major limitations regarding WBPIA.…”

“…These results are in concordance with a recent study using the PFA100 which did not document a difference in platelet function between hyperthyroid and euthyroid cats. 18 Our study does have some major limitations regarding WBPIA. Only the cats whose CBCs performed the day of WBPIA had adequate platelet numbers (>100 000 cells/μL) could be analyzed, leading to exclusion of some subjects.…”

“…The lack of screening for underlying cardiac disease was a limitation of this study. 18 The aim of the present study was to evaluate platelet function and hemostasis in both a hyperthyroid and a euthyroid group with 2 viscoelastic methods (VCM-Vet and ROTEM) and whole blood platelet impedance aggregometry (WBPIA). Our hypothesis was that hyperthyroid cats would show evidence of altered hemostasis suggestive of a potential hypercoagulable state when compared to euthyroid controls.…”

Platelet function analyzer‐200 closure curve analysis and assessment of flow‐obstructed samples

“…The time from initiation of flow to its termination is the "closure time" (CT) which is the primary output of the analyzer. 3 While the PFA has been used in the diagnosis and monitoring of several human and veterinary platelet disorders 3,4 and for investigation of platelet function in cats with systemic disease, 5,6 a current primary role in veterinary medicine is to assess the effect of clopidogrel. [7][8][9][10][11][12] Two cartridges have been designed for this purpose; the COL/ ADP cartridge, which is compatible with both analyzers and the P2Y cartridge, which claims greater sensitivity and is only compatible with the PFA-200 and upgraded PFA-100.…”

Study on the epidemiology and the clinical importance of selected infectious, parasitic and metabolic diseases in cats from Greece

“…The most common haematologic and serum biochemistry abnormalities associated with feline hyperthyroidism include anaemia, leucocytosis, increased activities of alanine aminotransferase (ALT) and alkaline phosphatase (ALP), decreased calcium and increased inorganic phosphorous concentrations and decreased potassium osmolalities Milner et al, 2006;Frenais et al, 2009;Williams et al, 2013;Hiebert et al, 2020).…”