Euthyroid Sick Syndrome is also known as what?

• A. Non-thyroidal illness
• B. Hypothyroid disease
• C. Autoimmune thyroiditis
• D. Endemic goiter

Answer: (A)

Euthyroid Sick Syndrome describes abnormal thyroid tests that occur in people with acute or chronic non-thyroidal illness, even though they are clinically euthyroid. The pattern is often low T3 with normal or low T4 and generally normal or only mildly suppressed TSH. Because the thyroid gland itself isn’t the problem, this situation is best described by the name non-thyroidal illness (NTIS), which is the term most clinicians use to capture this syndrome.

This distinction matters: it isn’t hypothyroid disease caused by autoimmune destruction or iodine deficiency (those conditions would have true thyroid gland dysfunction and different test patterns). The focus in management is treating the underlying illness, not starting thyroid hormone replacement based solely on these test results.