hormones play an essential role for metabolism, growth and
differentiation. Therefore, exact regulation of thyroid hormone levels
is vital for most organisms. Although the principles of thyrotropic feedback control have been described decades ago we still have not yet gained a comprehensive understanding of its dynamics.
significant progress has been made with mathematical modelling of
thyroid homeostasis. However, due to nonlinear interactions, these
cybernetic modells cannot simultaneously describe static and dynamic
behaviour. This gap may be filled with computer simulations that
additionally provide a more intuitive insight into the dynamics of
is an interactive simulation program of pituitary thyroid feedback
control that enables one to study the relationship between structure
and behaviour of thyroid homeostasis, i.e. between the architecture of
the intercausal network and the resulting hormone levels. Its goal is
to support both science and education in thyroidology.
is based on a parametrically isomorphic model of the overall system.
Applications of this program cover research, including development of
hypotheses, and education of students in biology and medicine, nurses and patients.
SimThyr has significantly contributed to research on thyroid homeostasis. It helped to prove a new hypothesis about the emergence of pulsatile TSH release and it delivered key indications that central hyperdeiodination leads to low T3 syndrome in humans. Additionally, it suggested the existence of epigenetic effects of thyroid status on central homeostasis.
Other research projects used SimThyr to investigate the effects of
certain structure parameters of the feedback loop on diagnostic quality
in the evaluation of thyroid function. Furthermore, the software is
used for educational projects at several locations.
The algorithms underlying the continuous simulation process have been released in several publications.
They may also be applied in form of classical mathematical modelling.
However, using them in a computer simulation provides a deeper and more
intuitive insight into temporal dynamics of thyroid homeostasis.
Over the previous years, SimThyr has received several certificates and awards.
is a free and open source application that is offered on the base of a
BSD licence. Binaries are available for Mac OS, Mac OS X and Windows,
source code requires THINK Pascal (for Mac OS Classic) or Lazarus/Free
Pascal (for Mac OS X, Windows and Linux).