Thyroid Screening During Early Pregnancy and the Need for Trimester Specific Reference Ranges: A Cross-Sectional...

Area of Science:

• Endocrinology
• Maternal-Fetal Medicine
• Public Health

Background:

• Thyroid hormone imbalances during pregnancy can lead to severe maternal and fetal complications.
• Screening for maternal thyroid dysfunction relies on thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels, typically compared against population-based trimester-specific reference ranges.
• Existing reference ranges may not accurately reflect local populations, necessitating local validation.

Purpose of the Study:

• To determine the prevalence of thyroid hormone derangements in early pregnancy within the local Pakistani population.
• To assess the necessity of establishing trimester-specific reference ranges for thyroid hormones in Pakistan.

Main Methods:

• A multi-centric, cross-sectional population survey was conducted in Lahore, Pakistan.
• Serum TSH and FT4 levels were measured in 293 pregnant women.
• Data were analyzed using SPSS version 23, comparing results against laboratory-specific reference ranges.

Main Results:

• The study found a significant prevalence of thyroid dysfunction: overt hyperthyroidism (4.10%), subclinical hyperthyroidism (16.38%), subclinical hypothyroidism (4.44%), and overt hypothyroidism (4.44%).
• Normal thyroid function was observed in 70.65% of the participants.
• Mean FT4 and TSH levels were 15.03 (±5.62) pmol/L and 2.53 (±6.82) mIU/L, respectively.

Conclusions:

• A substantial prevalence of thyroid dysfunction exists in the first trimester of pregnancy in Pakistan.
• There is a critical need for enhanced thyroid screening in early pregnancy to mitigate maternal and fetal risks.
• Development and implementation of Pakistan-specific, trimester-specific reference ranges for thyroid hormones are essential.