Journal of Thyroid Research / 2011 / Article / Tab 2

Research Article

First- and Second-Trimester Reference Intervals for Thyroid Hormones during Pregnancy in “Rhea” Mother-Child Cohort, Crete, Greece

Table 2

Thyroid hormones according to gestational age, Rhea mother-child cohort, Crete, Greece.

Distribution2.5th percentiles97.5th percentileMedianMeanSDReference range

1st trimester
TSHa IU/mL141Not normal0.052.531.021.080.610.05–2.53
free T3b  pg/mL (pmol/L)141Normald1.84 (2.83)5.39 (8.28)3.21 (4.93)3.38 (5.19)0.94 (1.44)1.54–5.22 (2.37–8.02)
free T4c  ng/dL (pmol/L)139Normale0.96 (12.36)1.60 (20.59)1.24 (15.96)1.24 (15.96)0.15 (1.93)0.95–1.53 (12.23–19.69)

2nd trimester
TSHa IU/mL257Not normal0.182.731.141.230.650.18–2.73
free T3b pg/mL (pmol/L)256Normal 1.99 (3.06) 5.30 (8.14) 3.52 (5.41) 3.55 (5.45) 0.87 (1.34) 1.78–5.29 (2.73–8.13)
free T4c ng/dL (pmol/L)258Normal 0.84 (10.81) 1.44 (18.53) 1.16 (14.93) 1.16 (14.93) 0.15 (1.93) 0.87–1.45 (11.20–18.66)

TSH: thyroid-stimulating hormone; free T3: free triiodothyronine; free T4: free thyroxine.
aDifference between first and second trimester: .
bDifference between first and second trimester: .
cDifference between first and second trimester: .
dAfter outlier deletion and log transformation.
eAfter outlier deletion.

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