SPINA (structure parameter inference approach) is a method that delivers estimated structure parameters of endocrine feedback control systems in vivo from serum or plasma hormone levels. The algorithm is based on equilibrium analysis of a compartmental nonlinear model.
A first successful implementation applies to evaluation of thyroid function. It allows for calculating the thyroid's maximum secretory capacity (GT or SPINA-GT) and the sum activity of peripheral 5'-deiodinases (GD or SPINA-GD) from levels of TSH, (F)T4 and (F)T3 that have been determined once only (SPINA Thyr).
This method is increasingly used in experimental research. SPINA Thyr has been evaluated in clinical trials covering more than 10,000 subjects with various disorders of thyroid homeostais. Additional applications targeting other endocrine feedback loops are currently being developed or prepared, respectively.
SPINA Thyr is a free application that calculates GT and GD. It is offered on the base of a BSD licence. Binaries are available for Mac OS, Mac OS X, Palm OS, Garnet OS and Windows. For other operating systems, including Linux, Solaris and BSD, SPINA Thyr is available as sourcecode. Building from source requires THINK Pascal (for Mac OS Classic), winsoft PocketStudio (for Palm OS / Garnet OS) or Lazarus/Free Pascal (for Mac OS X, Windows, Linux, BSD and Solaris). A special version of the calculation engine is available for modern S implementation, e.g. R.