TSH testing can help distinguish primary hypothyroidism from other causes of low serum T4 concentrations, such as pituitary gland dysfunction.

In primary hypothyroidism, TSH is elevated in an attempt to stimulate the thyroid gland to produce more T4;
In contrast, when T4 is low due to pituitary gland dysfunction, TSH may not be elevated or even decreased.

Veterinarians consider laboratory test results such as cTSH, clinical signs, and individual differences in animals when formulating treatment plans.
Therefore, accurate detection of cTSH levels provides veterinarians with important clinical decision support.