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

Table 3

Comparison between reference ranges for thyroid hormones as calculated by our analysis and those proposed by the manufacturer.

Reference ranges	TSH (𝜇IU/mL)		free T4 (ng/dL)		free T3 (pg/mL)
	1st trimester	2nd trimester	1st trimester	2nd trimester	1st trimester	2nd trimester
Rhea cohort	0.05–2.53	0.18–2.73	0.95–1.53	0.87–1.45	1.54–5.22	1.78–5.29
Manufacturer	0.4–4		0.89–1.76		1.8–4.2

TSH: thyroid-stimulating hormone; free T3: free triiodothyronine; free T4: free thyroxine.