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.

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.

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

Eligible are subjects addmitted for in-patient treatment after syncope or cerebral seicure

Anonymised data may be shared upon request.