Serum 3,3′,5′-Triiodothyronine (rT₃) and 3,5,3′-Triiodothyronine/rT₃Are Prognostic Markers in Critically Ill Patients and Are Associated with Postmortem Tissue Deiodinase Activities

Abstract

In critically ill patients who required more than 5 d of intensive care, rT3 and T3/rT3 were already prognostic for survival on d 1. On d 5, T4, T3, but also TSH levels are higher in patients who will survive. Serum rT3 and T3/rT3 were correlated with postmortem tissue deiodinase activities.

Physiological role and regulation of iodothyronine deiodinases: A 2011 update

“…Whether these changes are teleologically beneficial (for example, to reduce the metabolic rate during stressful circumstances) or a maladaptive process is still a matter of debate. However, the degree of reduction in thyroid hormone levels in these conditions does correlate with their mortality (85,86). The mechanisms underlying these multifactorial endocrinological alterations are not completely defined.…”

“…Peripherally, the decrease in circulating T3 levels, the most common abnormality in patients with NTIS, is mainly due to a reduced activation of T4 to T3 by D1 and D2 (87) and accelerated inactivation of T3 and T4 by D3. Sick patients often show both a robust reactivation of D3 in liver and skeletal muscle and a decreased liver D1 activity (86,88).…”

“…Moreover, since D1 is a T3-responsive gene, a reduction in this enzyme is further accentuated as the T3 falls. The role of D2 in the whole picture is poorly defined, its activity being decreased (86), unaltered (89) or increased (90) in skeletal muscle of severely ill patients. Furthermore, a potential contribution of a reduction in thiol cofactor of D1 or D2, due to an increase in the intracellular reactive oxygen species, is likely but not yet documented.…”

Thyroid abnormalities in term infants with fungal sepsis

“…[4][5][6][7][8] NTIS has been used as an interesting parameter of severity, since it has been verified that more severe patients have more prolonged alterations and a later recovery, and that the prognosis in adults is poor, and may even lead to death. [9][10][11][12] However, there are still no reports of there being a worse prognosis in infants, let alone those presenting fungal sepsis.…”

“…[19][20][21][22][23][24][25][26][27][28] Currently, four stages of NTIS are recognized in adults and children, known as low T3 syndrome, low T3-T4 syndrome, high T4 syndrome, and mixed syndromes. [4][5][6][7][8][9][10][20][21][22][23][24][25][26][27][28] Low T3 syndrome This is characterized by low serum levels of T3, normal or slightly increased TSH, and normal free T4 and T4. The level of reverse T3 may be normal or increased.…”