From the Research
Sick thyroid syndrome, also known as euthyroid sick syndrome or nonthyroidal illness syndrome, is a condition where patients with severe non-thyroid illnesses show abnormal thyroid function tests despite having normally functioning thyroid glands, and treatment should focus on addressing the underlying illness rather than correcting the thyroid abnormalities. This condition typically presents with low levels of triiodothyronine (T3), normal or low thyroxine (T4), and normal or low thyroid-stimulating hormone (TSH) 1. It's commonly seen in critically ill patients suffering from conditions like sepsis, major trauma, heart failure, or during starvation. The body deliberately reduces thyroid hormone activity as an adaptive response to conserve energy during severe illness. Some key points to consider in the management of sick thyroid syndrome include:
- The degree of thyroid function impairment correlates with disease severity and low levels of thyroid hormones, particularly thyroxine, predict a poor prognosis 1.
- Interpretation of thyroid function tests in the critically ill patient can be difficult and differential diagnosis of euthyroid sick syndrome is challenging, particularly in patients in whom no test results from before the onset of a critical illness are available 1.
- Thyroid hormone replacement is not recommended in most cases, as it may interfere with the body's natural adaptive mechanisms 2.
- Healthcare providers should distinguish this syndrome from true thyroid disorders through careful clinical assessment and laboratory testing, considering that premature thyroid hormone supplementation could potentially harm rather than help these patients 3. The most recent and highest quality study on this topic is from 2017, which provides a comprehensive review of the pathogenesis, diagnosis, and clinical consequences of euthyroid sick syndrome, and discusses the pros and cons of its treatment 1.