The Changes of Thyroid Function and Related Factors in Critical Patients without Thyroid Illness in ICU: A Retrospective Cross-Sectional Study

Abstract

Objective: To retrospectively analyze the changes of thyroid function and related factors in critical patients with non-thyroid illness, hoping to find some indicators for the further examination of the thyroid function in the intensive care unit situation.

Methods: The clinical data of 52 patients admitted to the ICU of Fuzhou First Hospital in Fujian Province, China, from May 2018 to March 2019 were collected. Patients were allocated into the central hypothyroidism group (CH group, n = 21) and the low T₃ syndrome group (LT₃S group, n = 31) based on thyroid function. All related medical data were collected, and the correlations between variables were identified using Spearman's or Pearson's rank correlation coefficients.

Results: The Acute Physiology and Chronic Health Evaluation (APACHE) II score in the CH group and the LT₃S group were 20.6 ± 3.6 and 19.3 ± 3.6, respectively, measured within 24 hours following hospital admission. The mean value of thyroid-stimulating hormone (TSH) in the CH group (0.3 ± 0.3 IU/mL) was significantly lower than that in the LT₃S group (1.7 ± 0.9 IU/mL), P < 0.001. Fasting plasma glucose (FPG) level in the CH group was significantly higher than that in the LT₃S group (10.3 ± 5.0 mmol/L vs 6.8 ± 2.5 mmol/L, P = 0.002).

Conclusion: Central hypothyroidism may exist in critically ill patients and may be associated with elevated fasting plasma glucose levels; accordingly, it should be included as part of patient assessment. When FPG is higher than 6.4mmol/L on admission, thyroid function should be actively examined.

Keywords: central hypothyroidism; critical illness; fasting blood glucose; thyroid-stimulating hormone.

Figure 1

(A) Fasting blood plasma glucose level was negatively correlated with serum thyroid-stimulating hormone level; (B) fasting blood plasma glucose level was negatively correlated with serum reverse triiodothyronine level; (C) fasting blood plasma glucose level was not associated with serum free triiodothyronine level; (D) fasting blood glucose level was not associated with serum free tetraiodothyronine level.

Figure 2

With fasting plasma glucose as the variable and central hypothyroidism as the grouped variable, the receiver operating characteristic curve was created and the area under the curve was calculated as being 0.78.