Autoantibodies against thyroid hormones: a case report about a dog with hypothyroidism and increased concentrations of T4 and T3 [German]

摘要

The article is about a two year old Do-Khyi (Tibetan Mastiff) with distinct clinical symptoms of hypothyroidism. The dog showed autoantibodies to T4 and T3, which - through in vitro interference - led to a false increase of the T4- and T3-serum levels. Free T4 was first measured with an analogue radioimmunoassay and was identified as highly raised. The measuring by equilibrium dialysis assay showed, however, that in reality the concentration of free T4 was very low (below detection limit). Ultrasonographically, both thyroid glands were small and hypoechoic compared to the surrounding tissue. The dog responded very well to the treatment with levothyroxin and the free T4, measured by equilibrium dialysis assay, increased, into the normal range. This case points out that diagnostic problems can arise with dogs producing autoantibodies to thyroid hormones. The measurement of free T4 by means of equilibrium dialysis assay is very useful for both diagnosis and therapeutic monitoring.