Changes in the pituitary — thyroid system during extracorporeal membrane oxygenation: a prospective observational study

Abstract

INTRODUCTION: The severity of the patient's condition that required ECMO and the changes observed in the pituitary — thyroid system (decreased T4 and T3 levels, low-normal or decreased TSH level) can be considered as a lack of body reserves due to the developed critical illness. OBJECTIVES: Study changes of TSH, T3, T4 levels during the ECMO procedure, during weaning/death on the ECMO. MATERIALS AND METHODS: The prospective observational study was performed in intensive care unit (47 patients on ECMO). After connecting ECMO (D0), (D1-D3-D5-D7-D9), and until the completion of ECMO, assessment of TSH, FT4, FT3 levels was carried out. OBJECTIVE: Analysis of changes in thyroid hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) levels in blood plasma during ECMO, at ECMO weaning/death on ECMO. RESULTS: On the day of ECMO (D 0) and every second day, median FT4 levels were D0 (p = 0.03); D1 (p = 0.03); D3 (p = 0.05), D11 (p = 0.02) and last observation day (p = 0.009) between surviving and dying patients respectively. T3 level D5 (3.1–1.9; p = 0.002); D11 (3.7–2.5; p = 0.05), last day of follow-up (3.1–2; p = 0.001), respectively. On the last day of ECMO between the survived and non-survived patients there were the following: differences in TSH levels; negative correlation of lactate levels, SOFA score and FT3, TSH, FT4. The analysis of the ROC curve (low levels of FT3, FT4, TSH in plasma in patients on the last day of ECMO) indicates a prognostically unfavorable outcome. CONCLUSIONS: The moment of ECMO connection initiation is regarded as subacute phase critical illness. Along with a high level of plasma lactate and high score of SOFA scale, the level of decrease in FT3, FT4 and TSH in patients correlates with the lethal outcome. Low levels of TSH, FT4, and FT3 may be considered as a predictor of adverse outcome at the time of weaning/death on ECMO.