The Association Between Hypoxic-Ischemic Encephalopathy and Thyroid Hormones

Area of Science:

• Neonatal Medicine
• Endocrinology
• Pediatric Neurology

Background:

• Hypoxic-ischemic encephalopathy (HIE) is a serious birth complication.
• Therapeutic hypothermia (TH) is a standard treatment for neonatal HIE.
• Thyroid function can be affected by HIE and TH, but data is limited.

Purpose of the Study:

• To compare serum TSH and fT4 levels in neonates with different HIE stages undergoing TH.
• To evaluate TSH and fT4 levels in neonates with HIE/TH versus a control group.

Main Methods:

• Retrospective study (January 2020 - December 2022).
• Compared neonates with HIE/TH (stage 2 and 3) to neonates with transient tachypnea of the newborn (TTN).
• Measured serum TSH and fT4 on the fifth postnatal day.

Main Results:

• Stage 3 HIE/TH neonates had lower TSH and fT4 than stage 2 HIE/TH.
• HIE/TH neonates showed higher TSH but similar fT4 compared to TTN controls.
• Higher TSH elevation rates in HIE/TH (especially stage 2) vs. TTN.
• Higher low fT4 rates in stage 3 HIE/TH vs. TTN.

Conclusions:

• TSH and fT4 levels vary by HIE stage in neonates treated with TH.
• Interpreting day 5 thyroid function tests in HIE/TH neonates requires caution due to potential elevations in TSH and decreases in fT4.
• These findings may prevent unnecessary repeat testing in HIE/TH infants.