Changes in thyroid function in patients with liver failure and their clinical significance: A clinical study of non-thyroidal illness syndrome in patients with liver failure

Abstract

Background: Non-thyroidal illness syndrome (NTIS) develops in a large proportion of critically ill patients and is associated with high risk for death. We aimed to investigate the correlation between NTIS and liver failure, and the short-term mortality of patients with these conditions.

Methods: The clinical data of 87 patients with liver failure were collected retrospectively, 73 of them were randomly selected for an observational study and to establish prognostic models, and 14 for model validation. Another 73 sex- and age-matched patients with mild chronic hepatitis were randomly selected as a control group. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were measured. The clinical characteristics of patients with liver failure and NTIS were analyzed. The follow-up of patients lasted for 3 months. Additionally, the values for predicting short-term mortality of model for end-stage liver disease (MELD), Child-Turcotte-Pugh (CTP), chronic liver failure-sequential organ failure assessment (CLIF-SOFA) scores, FT3-MELD model, and FT3 were evaluated.

Results: The observation group had significantly lower FT3 (2.79 ± 0.71 vs. 4.43 ± 0.75 pmol/L, P < 0.001) and TSH [0.618 (0.186-1.185) vs. 1.800 (1.570-2.590) mIU/L, P < 0.001], and higher FT4 (19.51 ± 6.26 vs. 14.47 ± 2.19 pmol/L, P <0.001) than the control group. NTIS was diagnosed in 49 of the patients with liver failure (67.12%). In the observation group, patients with NTIS had a higher mortality rate than those without (63.27% vs. 25.00%, P = 0.002). Across the whole cohort, the 3-month mortality was 50.68%. The international normalized ratios (INR) were 2.40 ± 1.41 in survivors and 3.53 ± 1.81 in deaths (P = 0.004), the creatinine (Cr) concentrations were 73.27 ± 36.94 µmol/L and 117.08 ± 87.98 µmol/L (P = 0.008), the FT3 concentrations were 3.13 ± 0.59 pmol/L and 2.47 ± 0.68 pmol/L (P < 0.001), the MELD scores were 22.19 ± 6.64 and 29.57 ± 7.99 (P < 0.001), the CTP scores were 10.67 ± 1.53 and 11.78 ± 1.25 (P = 0.001), and the CLIF-SOFA scores were 8.42 ± 1.68 and 10.16 ± 2.03 (P < 0.001), respectively. FT3 was negatively correlated with MELD score (r = -0.430, P < 0.001). An FT3-MELD model was established by subjecting FT3 concentration and MELD score to logistic regression analysis using the following formula: Logit(P) = -1.337 × FT3+0.114 × MELD+0.880. The area under the receiver operating characteristic (ROC) curve was 0.827 and the optimal cut-off value was 0.4523. The corresponding sensitivity and specificity were 67.6% and 91.7%. The areas under the ROC curve for FT3 concentration, MELD score, CTP score, and CLIF-SOFA score were 0.809, 0.779, 0.699, and 0.737, respectively.

Conclusions: Patients with liver failure often develop NTIS. FT3-MELD score perform better than CTP and CLIF-SOFA scores in predicting mortality in patients with liver failure. Thus, the FT3-MELD model could be of great value for the evaluation of the short-term mortality of such patients.

Keywords: Free triiodothyronine; Liver failure; Non-thyroidal illness syndrome; Prognosis.