TABLE 6.

Correlation between UIC and various measures of dietary iodine intake in sex- and life stage–specific subgroups of the “matched” population¹

		Correlation between UIC and iodine intake2 from
	n	Foods and DW	Foods and DS	Foods, DW, and DS	Foods, DW, DS, and SC	Foods, DW, DS, SC, and ST
Age
6–18 y	3875	0.23	0.25	0.25	0.24	0.24
≥19 y	8726	0.16	0.21	0.20	0.19	0.19
Sex
Male	6057	0.20	0.23	0.22	0.21	0.21
Female3	6294	0.15	0.19	0.18	0.17	0.17
Pregnancy status
Nonpregnant, 14–50 y	3073	0.12	0.15	0.14	0.13	0.13
Pregnant, 14–50 y	250	0.36	0.40	0.39	0.40	0.40

¹The “matched” population consisted of the 13,043 participants in NHANES 2003–2010 who provided both UIC data and dietary intake data. Analysis was based on dietary intake data gathered at the in-person interview on survey day 1, the same day that urine was collected for analysis. Kelp-containing DS were excluded when calculating the iodine intakes of participants who reported their use (n = 39) to avoid biasing the summary statistics toward high values inconsistent with the overall distributions. Participants with UICs >1000 μg/L (n = 106) were excluded from the correlation analyses to avoid biasing the results toward nonrepresentative data pairs at the extreme high end of the UIC distribution. The iodine concentration of DW was assumed to be 9.2 μg/L, the median of values reported in several studies. P < 0.0001 for all comparisons. DS, dietary supplements; DW, drinking water; S_C, salt used in cooking; S_T, salt used at the table; UIC, urinary iodine concentration.

²Pearson correlation coefficient, P < 0.05.

³Excluding pregnant females.