Table 5.

Comparison of iodine status and thyroid volume in 6-year-old children living in iodine-sufficient areas.

Country	Median UICa, μg/L	Iodine excess a, %	Total					Boys			Girls			Reference
			n	Tvol, mL		Goiter rate, %		n	Tvol, mL		n	Tvol, mL
				P50	P97	AS	BSA-S		P50	P97		P50	P97
South Korea	623.5	73.7	228	2.4	4.1	25.9	34.6	123	2.3	4.0	105	2.5	4.2	This study
Six countriesb	203	26.4	468	–	–	–	–	–	1.6	2.9	–	1.6	2.8	Zimmermann et al. (18)
Japan	281	45.9	37	1.9	3.9	5.8	6.5c	19	1.8	3.8	18	1.9	3.8	Fuse et al. (21)
Sweden	125	3.0	95	–	–	15.7	22.3c	47	2.6d	ns	48	2.6d	ns	Nystrom et al. (22)
Algeriae	565	84.0	55	3.0	ns	58.2	ns	–	–	–	–	–	–	Henjum et al. (23)
Chinaf	170	18.8	416	–	–	–	–	209	2.7	ns	207	2.8	ns	Zou et al. (24)
Japan	–	–	1594	–	–	–	–	822	ns	5.2	772	ns	5.1	Suzuki et al. (25)
Spain	120	ns	–	–	–	32	5c	–	ns	3.9	–	ns	4.1	Garcia-Ascaso et al. (26)
Koreaf,g	–	–	61	–	–	–	–	37	3.6d	ns	24	3.2d	ns	Sea et al. (27)

^aMedian UIC values and prevalence of iodine excess (UIC ≥ 300 µg/L) were derived from study participants of all ages; ^bCountries include Switzerland, Bahrain, South Africa, Peru, USA, and Japan; ^cData from all age groups; ^dMean value; ^eSaharawi refugee camp; ^fData from participants 3–6 years of age; ^gTvol was assessed using computed tomography.

AS, age-specific; BSA-S, body surface area specific; ns, not stated; P50, 50th percentile; P97, 97th percentile; Tvol, thyroid volume; UIC, urine iodine concentration.