Expected and unexpected TT4 concentrations in cats grouped by age.

TT4 concentrations in each age group are reported. The values are described by 25th percentile, 50th percentile (median), 75th percentile, IQR, expected TT4 concentration (low and high), and outlier values. The gray shading represents identical values for expected and unexpected TT4 concentrations in cats aged 1 through 9 years. The number of TT4 samples that exceed 3.5 ug/dL, and the percentage of these unexpected outliers in each age group are reported.