. 2014 Aug 1;24(8):1195–1209. doi: 10.1089/thy.2014.0052

Table 3.

Intervention Studies Investigating the Effect of Iodine Supplementation on Tg in Pregnant Women

Authors	Age (years)^a; country	Study design^b	Group^c	UIC (μg/L)^d				Tg (μg/L)^d				Findings	Comments
Liesenkötter et al. (80)	21–40; Germany	Women (n=108) randomized to receive either iodine supplements (300 μg I/day) or no iodine until 0.5 months PP		1st trimester^e	0.5 months PP^e			1st trimester^g	0.5 months PP^g			Women taking iodine supplements did not have a significantly lower Tg in the 1st trimester and 0.5 months PP	Unequal group sizes (38 women in iodine supplemented group while 70 women in no iodine group); 14 women had goiter previously
			0 μg	55	50^f			16.6	13.5
			300 μg	49	105			16.5	8.3
Nøhr et al. (81)	18–35; Denmark	Women (n=66) randomized to receive a vitamin and mineral tablet with 0 (placebo) or 150 μg I daily until 9 months PP		Trimesters				Trimesters				Women taking supplements had a significantly lower Tg than women taking placebo in the 3rd trimester (p=0.001)	All women were thyroid peroxidase antibody-positive; PP data for Tg was available from a figure only
			0 μg	1st	3rd			1st	3rd
			150 μg	51	53			17.1	19.4
				51^g,h	105			18.0^f,g	14.1
Santiago et al. (82)	31; Spain	Women (n=131) randomized to receive either IS, 200 μg, or 300 μg I daily until 3–6 months PP		Trimesters^g			3–6 months PP	Trimesters^g			3–6^g months PP	There was no significant difference in Tg within groups (p=0.13) or between groups (p=0.21)	All pregnant women were not iodine supplemented before enrolling in the study; 32% of pregnant women took IS at least 1 year before their pregnancy
				1st	2nd	3rd		1st	2nd	3rd
			IS	145	130	144	NA	21.3	22.7	22.1	16.7
			200 μg	117	177	166	NA	25.4	21.6	24.8	14.9
			300 μg	137	222	212	NA	13.0	8.4	13.9	18.1

^{^a}

Range used unless mean reported.

^{^b}

Only subjects with no known thyroid disease or negative for thyroglobulin antibody were included.

^{^c}

Actual quantity of iodine from supplement; Liesenkötter et al. (80) and Santiago et al. (82) used iodine supplements in the form of KI.

^{^d}

Median used unless mean reported.

^{^e}

UIC reported as μg/g creatinine.

^{^f}

Estimated value from a figure.

^{^g}

Mean.

^{^h}

Estimated value from a table.

IS, iodized salt; KI, potassium iodide.