Excerpt from EY3 of Dr. Bolton’s work.
An enunciation of the relationship between thyroid hormones and thyroid stimulating hormone during acute nonthyroidal illness and recovery will be postponed until after the statistical analysis is complete .
Total T4 is the most common hormone measured in dogs suspected of hypothyroidism and is low in cases of this disease. It can also decrease in dogs with nonthyroidal illness, frequently resulting in an inappropriate diagnosis of hypothyroidism and unnecessary thyroid hormone supplementation. The results of this study have demonstrated that total T4 normalization occurs in 80% of cases by hospital discharge and 96% of cases by the 2-week follow-up. Thus, in dogs diagnosed with acute nonthyroidal illness having a low total T4, rechecking this hormone 2 weeks following nonthyroidal illness resolution is likely to result in an accurate assessment of thyroid hormone status for the patient (i.e., normal total T4).