Association of Serum Total T4 and fPLI Concentrations in Cats
ACVIM 2008
J.M. Steiner1; M. Rick2; K.M. Aicher1; J.S. Suchodolski1
1Gastrointestinal Laboratory, Texas A&M University, College Station, TX, USA; 2Veterinary Endocrinology, Michigan State University, Lansing, MI, USA

Hyperthyroidism is common in cats and is often associated with clinical signs of gastrointestinal disease, such as vomiting, diarrhea, weight loss, and in rare cases anorexia. Chronic pancreatitis is also common in cats and is often associated with vague clinical signs that may include some of the same clinical sings observed in cats with hyperthyroidism. The objective of this study was to explore a possible association of serum total T4 and fPLI concentrations to determine whether hyperthyroid cats may be commonly affected by concurrent pancreatitis.

Left-over serum samples from 168 cats were used for this study. Serum total T4 (TT4; reference range: 10-55 nmol/L) and feline pancreatic lipase immunoreactivity (fPLI; reference range: 2.9-6.0 µg/L) concentrations were measured in all serum samples. All datasets were evaluated for normal distribution using a D'Agostino and Pearson omnibus normality test. Median serum fPLI concentrations were compared between cats with a serum TT4 within the reference range and those with an increased serum TT4 concentration using a Mann-Whitney test. The proportion of cats with a serum fPLI concentration outside the reference range (> 6.0 µg/L) or in the diagnostic range for pancreatitis (> 12 µg/L) were compared between cats with a serum TT4 within the reference range and those with an increased serum TT4 concentration using a Fisher's exact test. Significance was set at p < 0.05 for all statistical analyses.

Seventy-two cats had a serum TT4 concentration within the reference range and 88 cats had an increased serum TT4 concentration (range: 56 to >156 nmol/L). Serum fPLI concentrations in both groups of cats failed normality testing. Median serum fPLI concentration in cats with an increased serum TT4 concentration (10.2 µg/L) was not significantly different from that in cats with a serum TT4 concentration within the reference range (9.5 µg/L; p-value = 0.3874). The proportion of cats with a serum fPLI concentration above the upper limit of the reference range or above the diagnostic cut-off value for pancreatitis was not significantly different between cats with an increased serum TT4 concentration and those with a serum TT4 concentration within the reference range (p-values: 0.8119 and 0.7844, respectively).

In this study, we were unable to show a significant association of serum TT4 and fPLI concentrations, suggesting that feline pancreatitis is no more common in cats with an increased serum TT4 concentration than in those with a serum TT4 concentration within the reference range. One limitation of this study was the use of left-over serum samples, which precluded the evaluation of clinical findings and may have led to preferential inclusion of cats with clinical signs of gastrointestinal disease. Thus, further studies, evaluating serum fPLI concentrations in cats with a clinical diagnosis of hyperthyroidism would be warranted.

Speaker Information
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Joerg Steiner


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