From the Research
Sick thyroid syndrome, also known as euthyroid sick syndrome or non-thyroidal illness syndrome, is a condition where thyroid function tests appear abnormal in patients with severe non-thyroidal illnesses despite having normally functioning thyroid glands, and it typically does not require specific thyroid treatment, as the abnormal thyroid function tests usually resolve once the underlying illness improves 1.
Definition and Presentation
Sick thyroid syndrome typically presents with low levels of triiodothyronine (T3) and sometimes low thyroxine (T4), but with normal or low thyroid-stimulating hormone (TSH) levels. This syndrome occurs as the body's adaptive response to severe illness, including critical conditions like sepsis, major trauma, burns, heart failure, or after major surgery.
Pathophysiology and Clinical Impact
The changes in thyroid hormone levels are believed to be a protective mechanism to conserve energy during severe stress by reducing the body's metabolic rate. A recent study found that a significant 44.29% of patients with chronic heart failure exhibited low T3 levels, highlighting the substantial occurrence of sick thyroid syndrome in this population 1.
Diagnosis and Treatment
Unlike true thyroid disorders, sick thyroid syndrome does not typically require specific thyroid treatment. Treatment focuses on addressing the primary illness rather than correcting the thyroid hormone abnormalities. Physicians should avoid misdiagnosing this condition as primary hypothyroidism, as unnecessary thyroid hormone replacement therapy could potentially be harmful in these patients.
Key Considerations
- The syndrome is believed to be an adaptive response to illness, aimed at reducing the body's metabolic rate and conserving energy during severe physiological stress 1.
- Recognizing sick thyroid syndrome can guide tailored treatments, prompting intensive monitoring and optimized management of the underlying illness.
- Routine thyroid function assessments and regular monitoring of anemia are crucial in managing heart failure patients, as the study found a high prevalence of anemia, particularly among male patients 1.