TH influence cardiac function with different mechanisms: inotropic and chronotropic positive effect via nuclear and non-nuclear pathways in cardiomyocytes, increase in cardiac contractility through augmented tissue oxygen delivery and consumption decrease in systemic vascular resistance, through direct TH action on vascular smooth muscle cells other endocrine effects are exerted on renin-angiotensin-aldosterone axis and on erythropoietin secretion. ĭue to the importance of TH in cardiac function, it is not surprising that cardiac patients have been extensively studied under this profile. A retrospective study in a large group of patients treated with mechanical ventilation (MV) confirmed that NTIS represents a risk factor for prolonged MV. In a very recent paper in unselected ICU patients, free T 3 (fT 3) was the most powerful and the only independent predictor of ICU mortality, with a prognostic improving value when added to APACHE II score. Therefore we present a review of these recent results and some personal data in patients affected by chronic obstructive pulmonary disease and patients studied after major cardiovascular surgery.Ī low T 3 state has been described in a variety of clinical situations, such as starvation, sepsis, surgery, trauma, myocardial infarction and heart failure, cardiopulmonary bypass, respiratory failure, bone marrow transplantation, other severe illness. The role of intracellular oxidative stress (OS) has been underlined. The question is open and different reviews have been published on this topic but, very recently different molecular mechanisms have been shown to gain insight the complex situation of NTIS. ![]() Since there is no clear evidence of tissue hypothyroidism, such a condition seems to be an adaptative response, and thyroid replacement therapy is not usually required, but this topic is still debated, since indirect signs of true hypothyroidism at tissue levels have been showed. The hormonal response exhibits different pattern in acute and chronic phase, since in the first phase the alteration predominate in peripheral metabolism of TH, while in the latter central mechanisms controlling thyroid secretion progressively arise. Moreover, the severity of morbidity and outcome in patients studied in intensive care unit (ICU) has been correlated with the alteration in thyroid function. NTIS has been depicted in about 70% of hospitalized patients for different diseases. ![]() However, T 3 lowering is only one of the endocrine picture described is such a situation therefore the term NTIS seems to be more appropriate, also strengthening its extrathyroidal source. ![]() In critical illness, several abnormalities in thyroid hormone (TH) secretion, metabolism and action have been described in patients without previous diagnosis of intrinsic thyroid disease and are collectively called “Non thyroidal syndrome” (NTIS) this term is now largely employed, in the place of “euthyroid sick syndrome” or “low-T 3 syndrome”, due to the most common abnormality, a decreased level of serum total triiodothyronine (T 3), which can be detected very early, within 2 hours after the onset of severe physical stress.
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