Approach to a Quantitative Follow-up of Non-thyroidal Illness Syndrome (AQUA FONTIS)

• Assessment of the significance of an innovative physiological index approach (SPINA) in differential diagnosis between NTIS and latent thyrotoxicosis. [ Time Frame: Three weeks after admission to ICU (evaluation point 1.5) and additionally on day of discharge from the hospital (evaluation point 1.999) ] [ Designated as safety issue: No ]
  Diagnostic accuracy (sensitivity, specificity and AUCs of ROC analysis) of the thyroid's calculated secretory capacity (GT) for differentiation between NTIS and subclinical hyperthyroidism.
  
  

• Correlation of variables that quantify distinct components of NTIS with independent predictors of evolution, survival or pathophysiological condition and influencing or disturbing factors like medication. [ Time Frame: 24 hours (evaluation point 1.1), 72 hours (evaluation point 1.2) and further on weekly (evaluation points 1.3 to 1.5) after admission to the intensive care unit up to the day of discharge from hospital (evaluation point 1.999) ] [ Designated as safety issue: No ]
  

Detailed Description:

Non-thyroidal illness syndrome (NTIS or euthyroid sick syndrome) is a complex endocrine condition that may occur in critically ill patients. It is associated with significantly increased morbidity and mortality.

NTIS is characterised by three components that may occur single or in combination:

1. central hypothyroidism (transient thyrotropic insufficiency)
2. impaired protein binding of thyroid hormones and
3. reduced formation of T3 and increased conversion to rT3 (low-T3-syndrome).

Despite of long lasting research to some of its details NTIS is still poorly characterized in an integrative view. Additionally, it lacks a clinically usable classification.

Given the fact that patients with NTIS are faced with poor prognosis, several studies have been conducted in the past evaluating the question of possible treatment. However, they didn't yield unambiguous results, maybe due to the fact that these studies did not differentiate among the distinct components of NTIS.

Therefore, this study is intended to develop a clear-cut definition and classification of NTIS in order to set a foundation for future therapeutic studies.

This study recruits critically ill patients treated in medical and surgical intensive care units of the Bergmannsheil University hospitals for evaluation of integrative thyrotropic control and follow-up. From these data the correlation of individual prognosis with laboratory-defined components of NTIS will be determined.

This project is intended to:

1. deliver a prognostical aid by providing a differentiated classification,
2. to contribute to a standardised, rational and inexpensive diagnostical procedure and
3. to lay the foundation for future therapeutic trials by identifying subgroups that may benefit from therapy.