AQUA FONTIS is a unicentric, multidisciplinary, prospective cross-section and longitudinal study that aims at the development of a more clear-cut diagnostic definition and classification of non-thyroidal illness syndrome (NTIS).

Detailed Description:

Non-thyroidal illness syndrome (NTIS), also referred to as euthyroid sick syndrome (ESS) or thyroid allostasis in critical illness, tumors, uremia and starvation (TACITUS), 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.

Inclusion Criteria:

• Severe illness requiring intensive care
• Stay of at least 24 hours at the ICU

Exclusion Criteria:

• Substituted hypothyroidism or substitution in case of thyroid carcinoma
• Hyperthyroidism that is treated with thyrostatic agents and exhibits a THS level not below the reference region
• Manifest AIDS disease

Critically ill patients treated at three intensive care units of the Bergmannsheil university hospitals and that comply with the eligibility criteria.