Nonthyroidal illness in critically ill children

Prognostic role of euthyroid sick syndrome in MIS-C: results from a single-center observational study

Background

Euthyroid sick syndrome (ESS) is characterized by low serum levels of free triiodothyronine (fT3) with normal or low levels of thyroid stimulating hormone (TSH) and free thyroxine (fT4) and is reported in different acute clinical situations, such as sepsis, diabetic ketoacidosis and after cardiac surgery. Our aim was to evaluate the predicting role of ESS for disease severity in patients with Multisystem Inflammatory Syndrome in children (MIS-C).

Methods

A single-centre observational study on consecutive patients with MIS-C. Before treatment clinical, and laboratory data were collected and, in a subset of patients, thyroid function tests were repeated 4 weeks later. Variables distribution was analyzed by Mann-Whitney U-test and correlations between different parameters were calculated by Spearman's Rho coefficient.

Results

Forty-two patients were included and 36 (85.7%) presented ESS. fT3 values were significantly lower in patients requiring intensive care, a strong direct correlation was shown between fT3 and Hb, platelet count and ejection fraction values. A significant inverse correlation was retrieved between fT3 levels and C-reactive protein, brain natriuretic peptide, IL-2 soluble receptor and S-100 protein. Subjects with severe myocardial depression (EF < 45%) had lower fT3 values than subjects with higher EF. The thyroid function tests spontaneously normalized in all subjects who repeated measurement 4 weeks after admission.

Conclusion

ESS is a frequent and transient condition in acute phase of MIS-C. A severe reduction of fT3 must be considered as important prognostic factor for severe disease course, with subsequent relevant clinical impact in the management of these patients.

Biochemical indicators of euthyroid sick syndrome in critically ill children

OBJECTIVES

This study aimed to determine the prevalence and predictors of euthyroid sick syndrome (ESS) in pediatric intensive care, and to establish a link between thyroid function tests and mortality.

METHODS

Between January 2015 and March 2020, children admitted to our pediatric intensive care unit (PICU) and tested for free triiodothyronine (fT3), free thyroxine (fT4), and thyrotropin (TSH) levels were included. Patients with decreased fT3, with normal or decreased fT4, and normal or decreased TSH levels were assigned to the ESS group. The association between biochemical indicators and ESS, as well as the relationship between fT3 and mortality, were examined.

RESULTS

A total of 141 (36%) of 386 children included to study were classified in the ESS group. The ESS group had a higher rate of 28-day mortality (12 [8.5%] vs. 9 [3.7%]). Blood urea nitrogen (BUN), albumin, platelet, lactate, and pediatric index of mortality 3 [PIM3 (%)] were significantly associated with ESS (odds ratios in order: 1.024, 0.422, 0.729, 1.208, 1.013). Multivariate regression analysis showed that BUN, albumin, platelet, and lactate were independently associated with ESS progression. The area under curve (AUC [95%CI]) for fT3 was 0.644 (0.555-0.789) to detect mortality. Children with a fT3 level lower than 2.31 pg/mL had significantly higher 28-day mortality (log rank test, p=0.001).

CONCLUSIONS

Our study identified BUN, albumin, lactate, and platelet count as independent risk factors for ESS progression in children. Furthermore, our findings indicated a correlation between fT3 and mortality, which makes fT3 an ideal candidate to be included in mortality indices.

Non-thyroidal illness syndrome and SARS-CoV-2-associated multisystem inflammatory syndrome in children

PURPOSE

COVID-19 disease may result in a severe multisystem inflammatory syndrome in children (MIS-C), which in turn may alter thyroid function (TF). We assessed TF in MIS-C, evaluating its impact on disease severity.

METHODS

We retrospectively considered children admitted with MIS-C to a single pediatric hospital in Milan (November 2019-January 2021). Non-thyroidal illness syndrome (NTIS) was defined as any abnormality in TF tests (FT3, FT4, TSH) in the presence of critical illness and absence of a pre-existing hormonal abnormality. We devised a disease severity score by combining severity scores for each organ involved. Glucose and lipid profiles were also considered. A principal component analysis (PCA) was performed, to characterize the mutual association patterns between TF and disease severity.

RESULTS

Of 26 (19 M/7F) patients, median age 10.7 (IQR 5.8-13.3) years, 23 (88.4%) presented with NTIS. A low FT3 level was noted in 15/23 (65.3%), while the other subjects had varying combinations of hormone abnormalities (8/23, 34.7%). Mutually correlated variables related to organ damage and inflammation were represented in the first dimension (PC1) of the PCA. FT3, FT4 and total cholesterol were positively correlated and characterized the second axis (PC2). The third axis (PC3) was characterized by the association of triglycerides, TyG index and HDL cholesterol. TF appeared to be related to lipemic and peripheral insulin resistance profiles. A possible association between catabolic components and severity score was also noted.

CONCLUSIONS

A low FT3 level is common among MIS-C. TF may be useful to define the impact of MIS-C on children's health and help delineate long term follow-up management and prognosis.

Central hypothyroidism improves with age in very young children with Prader-Willi syndrome

OBJECTIVE

Abnormalities in the hypothalamic-pituitary-thyroid (HPT) axis have been implicated in Prader-Willi syndrome (PWS); however, limited information is currently available on age-dependent alterations in the HPT axis. We herein investigated age-dependent differences in thyroid hormone levels in PWS children.

DESIGN/PATIENTS/MEASUREMENTS

Free T4 (FT4), free T3 (FT3) and thyroid-stimulating hormone (TSH) concentrations were retrospectively compared between genetically confirmed PWS children (N = 43, median age: 11.2 months) and controls (N = 85, median age: 14.5 months) matched for age, sex, body weight-SD score (SDS), height-SDS, body mass index-SDS and serum albumin level, a marker of the nutritional status. Subjects were subdivided into two groups based on their age: an infant group aged between 1 and 11 months (PWS: N = 22, controls: N = 30) and a toddler group aged between 12 and 47 months (PWS: N = 21, controls: N = 55). None of the subjects had ever been treated with growth hormone or levothyroxine.

RESULTS

After adjustments for confounding variables, in the infant group, FT4 levels (pmol/L) were significantly lower in PWS (11.24 in PWS vs 14.32 in controls, P = .0002), whereas no significant differences were observed in FT3 or TSH levels. In the toddler group, no significant differences were noted in FT4 (12.23 in PWS vs 15.31 in controls, P = .10), FT3 or TSH levels. The FT3/FT4 ratio was significantly increased in PWS in both groups. FT4 levels were positively correlated with age in PWS.

CONCLUSIONS

Infants with PWS had lower FT4 levels, but FT3 levels were normal, indicating that the levothyroxine replacement therapy may not need to be routinely performed.