Iodothyronine antibodies are not correlated with prevalence or prognosis of non-thyroidal illness syndrome

Patients suffering from critical illness usually exhibit a characteristic functional state of thyrotropic feedback control that is referred to as non-thyroidal illness syndrome (NTIS). Today, there are still important questions unsolved, e.g. regarding the interdependence of immunological and endocrine functions in critical illness.

Therefore, in the context of the prospective AQUA FONTIS study we investigated 164 patients that were treated in medical, surgical and heart surgical intensive care units (ICUs) of the Bergmannsheil university hospitals in Bochum, Germany. Here, we examined the titres of antibodies reacting with thyroxine (T4-ab) and triiodothyronine (T3-ab) that were determined 24 h after admission to the ICU, and investigated their correlation with parameters of thyroid homeostasis, length of stay in hospital (LOSIH) or ICU (LOSICU) and survival of patients.

All patients exhibited Gaussian distributed antibody titres that were in the normal range for healthy volunteers. Moreover, the titres didn’t correlate with functional characteristics like thyrotroph thyroid hormone sensitivity index (TTSI) as a parameter for the central component of NTIS, or sum activity of 5′-deiodinase as a marker for impaired deiodination. Again, antibody titres didn’t exhibit correlation with survival, LOSIH or LOSICU, in the latter two cases even if only the subgroup of surviving patients was considered.

In conclusion, despite of immunological activation, e.g. in case of sepsis, antibodies directed against T3 or T4 are not elevated among critically ill patients nor do they play a role in the prognosis of the disease.

Endocrine Abstracts (2008) 16 P821