Trimester-specific reference intervals for thyroid function parameters in pregnant Caucasian women using Roche...

Area of Science:

• Endocrinology
• Reproductive Medicine
• Clinical Chemistry

Background:

• Standard thyroid function reference intervals (RI) are inadequate for pregnancy, potentially leading to incorrect treatments and adverse pregnancy outcomes.
• Accurate thyroid monitoring during gestation is crucial for maternal and fetal well-being.
• Previous studies highlight the need for pregnancy-specific thyroid function RIs.

Purpose of the Study:

• To establish trimester-specific reference intervals (RI) for thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) in healthy pregnant Caucasian women.
• To provide updated reference limits for thyroid function tests used on Roche platforms during pregnancy.
• To inform clinical practice regarding appropriate thyroid function assessment in pregnant individuals.

Main Methods:

• Longitudinal collection of blood samples from 139 healthy Caucasian pregnant women across all trimesters.
• Exclusion of participants with overt thyroid abnormalities (TSH > 10 mU/L) or positive TPO antibodies.
• Analysis of TSH, FT4, and FT3 levels using Roche platforms to calculate trimester-specific reference intervals.

Main Results:

• First-trimester TSH RI: 0.34-3.81 mU/L; second-trimester: 0.68-4.07 U/L; third-trimester: 0.63-4.00 mU/L.
• FT4 and FT3 concentrations progressively decreased during pregnancy, with third-trimester medians 14.8% and 13.2% lower than in the first trimester, respectively.
• Thyroid function parameters in the first trimester were comparable to post-partum measurements.

Conclusions:

• This study provides crucial trimester-specific reference intervals for TSH, FT4, and FT3 in pregnant Caucasian women.
• The findings support the adoption of these updated reference limits when utilizing Roche platforms for thyroid function testing during pregnancy.
• Implementing these specific RIs can enhance diagnostic accuracy and optimize management of thyroid disorders in pregnancy.