T4:FT4 Ratio

Hemopet’s Hemolife Diagnostics Division has discovered and patented an important novel diagnostic tool to evaluate thyroid disorders in dogs called the T4:FT4 Ratio. This ratio has been added to Hemolife’s portfolio of all “green” technology and breed- and age-specific interpretive analysis, and is available on all of Hemolife’s thyroid profile laboratory test results to assist veterinarians in diagnosing thyroid conditions more accurately. 

The T4:FT4 Ratio determines the ratio between the level of total T4 and its free, unbound fraction. This diagnostic tool provides enhanced specificity for canine thyroid disorders. Importantly, clinicians can now determine whether the values of the different thyroid analytes being measured indicate a thyroid disorder and/or some other underlying disease (non-thyroidal illness, NTI). Note that this ratio does not diagnose or rule out the presence of heritable autoimmune thyroiditis, where affected dogs have elevated thyroid autoantibodies (typically high thyroglobulin autoantibodies, TgAA).

Thyroid data from nearly 15,000 samples collected over the last 20 months were examined. Results from 1000 healthy dogs during a 6-week period revealed a tight T4:FT4 ratio ranging from 1.30-1.54. Ratios below 1.25, by contrast, indicated the presence of primary NTI or NTI secondary to hypothyroidism. A subset of 242 dogs with elevated liver cell-specific enzyme (high ALT) was further analyzed as a group confirmed to have NTI. Of these, 119 dogs were receiving thyroxine treatment for hypothyroidism. The T4:FT4 Ratio was a critical factor in distinguishing the dogs with primary hypothyroidism from those with primary or secondary NTI. The results were highly statistically significant (p=< 0.001). Further, the variance of T4 data for the 223 dogs with liver disease not receiving thyroxine was much higher than that of the 119 dogs with high ALT that had their hypothyroidism corrected by thyroid medication (2.225 vs 0.085).

This once again validates the need for doing comprehensive thyroid panels and the special importance of the T4 and free T4 data, along with measuring TgAA to exclude thyroiditis. Without this information, a disorder can be misdiagnosed or valuable effort and time expended on inaccurate care and treatment.

Using the Hemolife all “green” technology and breed- and age-specific interpretive analysis, plus the new T4:FT4 ratio, veterinarians and clients are once again assured of obtaining the leading thyroid technology profiles and analysis. Hemolife is the only veterinary diagnostic laboratory anywhere in the world that can provide these unique assays and analysis. Results are available within 24-48 hours.

Official Press Release: T4:FT4 Ratio – Clinical Breakthrough to Diagnose Thyroid Disorders in Dogs

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