Frequency of Non-Thyroidal Illness Syndrome in Pediatric Patients with Sepsis and Septic Shock

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Abstract Background Non-Thyroidal Illness Syndrome (NTIS) is considered when patients demonstrate abnormal thyroid functions and levels decrease at onset of infection and keep decreasing with disease progression. Levels usually get normalized after the illness is cured. NTIS is not studied well in pediatric population. Aim of the Work Assess the hormonal changes of NTIS in sepsis and septic shock patients. Furthermore, Follow up the severity of NTIS and its effect on outcome. Patients and Methods This study (1st phase: Cross-sectional, 2nd phase: Prospective) included 40 critically ill children categorized into two groups: (i) Sepsis group : was defined according to standard international criteria using pediatric Sequential Organ Failure Assessment (p SOFA) score and sepsis was considered when p SOFA score > 2 (ii) Septic shock group: was defined by a vasopressor requirement to maintain a mean arterial pressure ≥ 65 mm Hg and having a serum lactate level > 2 mmol/L despite adequate fluid resuscitation (Singer et al., 2016), with 20 patients in each group. Patients were admitted to the pediatric intensive care unit (PICU). Thyroid hormone levels were assessed and compared in day 1 and day 5 in all patients and subgroups. All patients were followed up until discharge or death. ROC curve and Univariate and multivariate approaches were used to assess the link between thyroid hormones and prediction of mortality. Results NTIS was found in 47.5% of patients. NTIS was higher among septic shock group than sepsis 65.5% versus 30% (p value = 0.027). NTIS was associated with each of ventilation, catecholamines infusion and SOFA score (p value =0.044, 0,027 and 0.033) respectively. FT3 (Free triiodothyronine) levels were lower and rT3 (reverse T3) levels were higher in day 5 of illness than day 1 (p value =0.041and 0.000) respectively. Furthermore, FT3 levels in day 5 were lower, and rT3 levels in day 1 and day 5 were higher in non survivors than survivors (p value =.0.002, 0.015 and 0.003) respectively. ROC curve to assess thyroid hormone levels, SOFA score and CRP (C-reactive protein) as predictors of mortality revealed that FT3 levels in day 5 was the best in predicting PICU mortality (sensitivity 100%, and specificity 68.42%), Followed by SOFA score day 5 (sensitivity 100%, and specificity 57.89%). In the multivariate regression analysis, we discovered that high rT3 levels in day1 and CRP in day 5 were independently associated with PICU mortality. Conclusion NTIS is common among critically ill children and higher among septic shock group than sepsis. Also, Beside the SOFA score, FT3 measured in day5 of illness and rT3 measured in day1 of illness were the best predictors of PICU mortality.