[Problems with interpretation of low levels of thyroidal hormones conditioned by changes in transport proteins]

In clinical practice, we often observe conditions accompanied by secondary drop of binding proteins that bind, more or less specifically, thyroidal hormones. This is usually considered as normal situation that is often not properly interpreted from clinical point of view. In other words, we tolerate such conditions because we build on values of free hormones FT3 and FT4. However, it is very rare to observe significant decrease or even absence of thyroxin binding globulin (TBG) due to inborn error of metabolism. In such situations, the overall level of thyroidal hormones becomes a part of evaluated laboratory profile. Unusual laboratory constellation is in sharp contrast to the so-called "healthy patient". Due to increased migration of persons, we had an opportunity to take care of a patient of this kind.