Observational and Diagnostical Study on Transient Allostatic Responses of Thyroid Function After Syncopation and Seizure

Study Overview
=================
Brief Summary
-----------------
Changes of thyroid function may occur after short loss of consciousness, but they haven't been systematically evaluated up to now, although occasional observations suggest temporal increases in TSH concentration. This study aims at assessing transient changes of biomarkers of thyroid function after syncopation and seizure. Results of the study might contribute to an improved detection rate of thyrotoxicosis.

Detailed Description
-----------------
Transient allostatic responses of thyroid function have been described in critical illness. Own observations suggest similar reactive responses after syncopation and cerebral seizures. They are marked especially by increased concentration of serum thyrotropin (TSH), suggesting a type 2 allostatic response. However, changes of thyroid function after temporal loss of consciousness haven't been systematically evaluated up to now. Current diagnostic guidelines recommend primarily the determination of serum TSH concentration for screening of thyroid function, and the measurement of peripheral thyroid hormones (T4 and/or T3) is only recommended if TSH determination results in pathological values. This TSH reflex strategy may be misleading after short-term loss of consciousness. This study aims at assessing the prevalence of allostatic responses of thyroid function after events of syncopation or seizure and at investigating the consecutive temporal development of biomarkers of thyroid function. An additional aim includes the diagnostic value of TSH determination, compared to measurement of free thyroid hormones, for thyroid dysfunction after syncopation or seizure. Results of this study might contribute to an improved detection rate of thyrotoxicosis. In cases of medical emergencies and in-patient treatment interventions with a significant iodine load are common, including the application of iodinated radiocontrast agents and amiodarone. In this setting, undetected hyperthyroidism may lead to thyroid storm, which is associated with a high mortality.

Official Title
-----------------
Observational and Diagnostical Study on Transient Allostatic Responses of Thyroid Function After Syncopation and Seizure (Thyro-Syncope)

Conditions
-----------------
Seizures, Syncope

Intervention / Treatment
-----------------
* Diagnostic Test: Evalution of thyroid function


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Admission after syncope or seizure Age of 18 years or older First bleed not later than two hours after event (syncope or seizure) Written informed consent obtained Exclusion Criteria: Results of thyroid hormones not available within two hours after event Pituitary dysfunction Thyroid dysfunction Use of iodinated radiocontrast agents less than three months ago Therapy with amiodarone in the previous three years Pregnancy

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Syncope<br>Subjects admitted immediately after syncopation. | Diagnostic Test: Evalution of thyroid function<br>* Determination of TSH, free T4, free T3, SPINA-GT, SPINA-GD and Jostel's TSH index<br>|
| Seizre<br>Subject admitted immediately after cerebarl seizure | Diagnostic Test: Evalution of thyroid function<br>* Determination of TSH, free T4, free T3, SPINA-GT, SPINA-GD and Jostel's TSH index<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of allostatic responses of thyroid function after short-term loss of consciousness | Prevalence of increased TSH immediately after syncope or seizure | 2 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time series of thyroid function after short-term loss of consciousness | Temporal evolution of TSH and thyroid hormone concentration during three days after syncope or seicure | 72 hours | 
| Diagnostic value of TSH after short-term loss of consciousness | Sensitivity, specificitay and likelihood ratios of TSH compared to free T4 and free T3 after syncopation or seizure | 72 hours | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
thyroid allostasis, TACITUS, syncope, seizure, loss of consciousness