Which test increases specifically in ESS/NTI?

Which test increases specifically in ESS/NTI?

• A. rT3
• B. FT4
• C. TSH
• D. TT4

Answer: (A)

In non-thyroidal illness (ESS/NTI), the body’s handling of thyroid hormones changes due to altered deiodinase enzyme activity. The conversion of thyroxine (T4) to the active hormone T3 is reduced, while the pathway producing reverse T3 (rT3) is favored. This shift causes rT3 levels to rise specifically, even as T3 levels drop and thyroid-stimulating hormone (TSH) often remains normal or only modestly affected. Free T4/T4 can be normal or low, but they don’t rise as a characteristic feature. So the test that increases specifically in ESS/NTI is reverse T3, reflecting the altered peripheral metabolism of thyroid hormones during illness.

In non-thyroidal illness (ESS/NTI), the body’s handling of thyroid hormones changes due to altered deiodinase enzyme activity. The conversion of thyroxine (T4) to the active hormone T3 is reduced, while the pathway producing reverse T3 (rT3) is favored. This shift causes rT3 levels to rise specifically, even as T3 levels drop and thyroid-stimulating hormone (TSH) often remains normal or only modestly affected. Free T4/T4 can be normal or low, but they don’t rise as a characteristic feature. So the test that increases specifically in ESS/NTI is reverse T3, reflecting the altered peripheral metabolism of thyroid hormones during illness.