NTIS Subtypes and Thyroid Autoantibodies Predict Mortality in Sepsis
Overview
Non-thyroidal illness syndrome (NTIS) is highly prevalent in septic patients and independently predicts in-hospital mortality. Specific NTIS subtypes, particularly isolated low T3 and combined low T3 and T4, are associated with a fourfold increased risk of death. Additionally, thyroglobulin antibody (TGAb) positivity doubles mortality risk, highlighting its prognostic value.
Background
Sepsis is a leading cause of death worldwide, with mortality rates remaining high despite advances in care. NTIS, characterized by altered thyroid hormone levels, is common in critically ill patients and reflects disruptions in thyroid hormone metabolism during systemic illness. While NTIS is linked to worse outcomes, the prognostic significance of its subtypes and the role of thyroid autoantibodies in sepsis have not been fully elucidated. This study investigates these associations to improve risk stratification in septic patients.
Data Highlights
Parameter
NTIS Prevalence
Mortality Risk (OR, 95% CI)
p-value
Overall NTIS
82% (715/871)
3.14 (1.52–7.00)
0.003
NTIS-1 (Isolated low T3)
Not specified
4.26 (1.33–16.41)
0.022
NTIS-2 (Low T3 and T4)
Not specified
3.99 (1.31–14.88)
0.024
TGAb positivity
Not specified
2.15 (1.30–3.60)
<0.01
TGAb positivity in NTIS subgroup
Not specified
1.97 (1.17–3.33)
0.011
TPOAb positivity
Not specified
1.74 (0.96–3.14)
0.068
Key Findings
NTIS was present in 82% of septic patients and independently predicted a threefold increased risk of in-hospital mortality.
NTIS subtypes NTIS-1 (isolated low T3) and NTIS-2 (combined low T3 and T4) were associated with approximately fourfold higher mortality risk.
Patients with NTIS were older, had more comorbidities, and exhibited more severe organ dysfunction (higher SOFA scores) compared to those without NTIS.
Thyroglobulin antibody (TGAb) positivity doubled the risk of death both in the overall cohort and within the NTIS subgroup.
Thyroid peroxidase antibody (TPOAb) positivity showed a trend toward increased mortality but did not reach statistical significance.
Incorporating thyroid function tests and thyroid antibody measurements may enhance risk stratification in septic patients.
Clinical Implications
Clinicians should consider assessing thyroid function and thyroid autoantibodies in patients with sepsis to identify those at higher risk of mortality. Recognizing NTIS subtypes, especially isolated low T3 and combined low T3 and T4, can aid in prognostication and potentially guide more tailored management strategies. TGAb positivity serves as a valuable prognostic biomarker and may warrant closer clinical monitoring.
Conclusion
NTIS is a common and independent predictor of mortality in sepsis, with specific subtypes conferring particularly high risk. Thyroglobulin antibody positivity further stratifies risk, underscoring the importance of integrated thyroid assessment in septic patients.
References
Study Authors/Shanghai Tertiary Hospital/2015-2019 -- Subtypes of Non-thyroidal Illness Syndrome and Their Relationship with Mortality in Sepsis
