Comparison of the Reference Intervals Used for the Evaluation of Maternal Thyroid Function During Pregnancy Using...

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Clinical Chemistry

Background:

• Maternal thyroid dysfunction is prevalent during pregnancy.
• Physiological changes can lead to misdiagnosis of thyroid disorders using standard reference intervals.
• Accurate thyroid function evaluation is crucial for maternal and fetal health.

Purpose of the Study:

• To compare sequential and nonsequential methods for evaluating thyroid function in pregnant women.
• To determine the most reliable method for establishing gestational trimester-specific reference intervals.
• To improve the accuracy of diagnosing thyroid dysfunction during pregnancy.

Main Methods:

• Prospective study comparing sequential and nonsequential methods for thyroid function testing.
• Serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels were measured.
• Reference intervals were established using the central 95% range (2.5th-97.5th percentiles).

Main Results:

• The nonsequential method showed significantly wider reference intervals for TSH and FT4 across trimesters compared to the sequential method.
• Significant differences in TSH and FT4 reference intervals were observed between the groups, particularly in the 3rd trimester.
• The sequential method provided narrower and more precise reference intervals, reducing the likelihood of diagnostic errors.

Conclusions:

• The sequential method is more appropriate for establishing thyroid function reference intervals during pregnancy.
• Trimester-specific reference intervals are essential for accurate maternal thyroid function assessment.
• Consideration of pregnancy-related complications in inclusion criteria is recommended for thyroid function testing.