SPINA (structure parameter inference approach) is a method for calculating constant structure parameters of endocrine feedback control systems in vivo from hormone levels obtained from serum or plasma.
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 and clinical trials. 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, sourcecode requires THINK Pascal (for Mac OS Classic), winsoft PocketStudio (for Palm OS / Garnet OS) or Lazarus/Free Pascal (for Mac OS X, Windows and Linux).