Cross-sectional analysis establishes TSH levels in pregnant women from iodine-deficient regions, suggesting misclassification risk using standard guidelines.
Key Points
This research aims to establish trimester-specific serum TSH reference ranges for pregnant women in iodine-deficient regions of Uttarakhand, India.
Cross-sectional observational study conducted in three districts of Uttarakhand.
Recruited 544 pregnant women across three trimesters using systematic random sampling.
Calculated trimester-specific reference ranges using 2.5th and 97.5th percentiles of TSH and measured urinary iodine excretion.
Mean TSH levels increased from 2.18±1.34 to 3.42±1.89 mIU/L across trimesters (p<0.001).
Reference ranges for TSH showed significant differences from international standards, with first trimester values of 0.12-4.87 mIU/L.
Using international ranges, 50.2% of women would be misclassified as having thyroid dysfunction compared to 30.3% with population-specific ranges.