As it has been previously reported that the plasma reverse triiodothyronine (rT3) levels generally remain normal in such patients, it can be inferred that the low FT3 levels are not connected to an enhanced conversion of T4 to the metabolically inactive rT3 (often seen in euthyroid sick syndrome in which the type 2 and 3 deiodinases are upregulated) [24], but are most probably due to the diminished conversion of T4 to T3 in the periphery. Here, CD4 is linked to euthyroid sick syndrome.