Serum Total Thyroxine Evaluation in Critically Ill Feline Patients

Abstract

This retrospective case control study compared serum total thyroxine (tT4) concentrations in hospitalized critical cats (CCs) and non-hospitalized cats with non-thyroidal chronic diseases (chronic group, CG) and evaluated the relationship between the serum tT4 concentration of CCs and systemic inflammation (systemic inflammatory response syndrome (SIRS)), disease severity (Acute Patient Physiologic and Laboratory Evaluation (APPLEfast)), and prognosis. Cats with previously suspected or diagnosed thyroid disease were excluded. Serum tT4 was evaluated in surplus serum samples at the time of admission for CCs and CGs. The APPLEfast score of the CC group was calculated at admission. The systemic inflammatory response syndrome (SIRS) in CCs was determined using proposed criteria. Cats were divided into survivors and non-survivors according to the discharge outcome. Forty-nine cats were retrospectively included. Twenty-seven cats died during hospitalization. The CG group was composed of 37 cats. The CC group showed a significantly lower tT4 compared to the CG group (1.3 ± 0.7 vs. 2 ± 0.9; p < 0.0001). Among SIRS, APPLEfast, and tT4, only tT4 was associated with mortality (p = 0.04). The tT4 cut-off point for mortality was 1.65 μg/dL (sensitivity 81%, specificity 57%, odds ratio (OR) 5.6). Twenty-five cats (51%) had SIRS that was not associated with tT4. Non-thyroidal illness syndrome can occur in critically ill cats and the evaluation of tT4 in hospitalized cats could add prognostic information.

Evaluation of cardiac troponin I as a predictor of death in critically ill cats

“…Additionally, while 1 study of cats with polytrauma found the scores to be significant prognosticators, 37 our findings of lack of prognostic value are in agreement with results from several other studies in cats that have applied the APPLE scores, suggesting a need for additional prognostic composite score development in cats. 17,[38][39][40][41] In contrast, several studies applying the APPLE scores in critically ill dogs have found the scores to be significant prognosticators for death. 3,5,42 Nevertheless, substantial overlap between survivors and nonsurvivors confirms that such scores are not useful (or intended) for prognostication of individual animals.…”

“…Additionally, while 1 study of cats with polytrauma found the scores to be significant prognosticators, 37 our findings of lack of prognostic value are in agreement with results from several other studies in cats that have applied the APPLE scores, suggesting a need for additional prognostic composite score development in cats. 17 , 38 , 39 , 40 , 41 …”