Table 1.

Urinary iodine concentration (UIC) by gender and area among schoolchildren aged 8–10 years (n 240 per year, selected by systematic random sampling each year) in West Azerbaijan Province, north-west Iran (2007–2015)

	UIC (μg/l)
	Total (n 240)			Boys (n 120)			Girls (n 120)			Urban (n 140)			Rural (n 100)
Year	Mean	sd	Median	Mean	sd	Median	Mean	sd	Median	Mean	sd	Median	Mean	sd	Median	P *	P †
2007‡	153·38	86·11	140	141·00	76·65	130	165·75	93·32	145	167·00	86·06	150	139·75	84·33	130	0·06	0·02
2008	205·67	113·71	180	197·42	117·73	170	213·92	109·41	190	229·57	106·76	210	172·20	115·21	145	0·17	<0·001
2009	155·67	101·67	130	149·50	89·56	130	161·83	112·53	130	163·43	100·54	140	144·80	102·75	110	0·9	0·05
2010	141·04	122·36	90	128·08	111·38	80	154·00	131·62	125	165·14	134·35	150	107·30	93·97	70	0·22	<0·001
2011	143·96	126·12	90	149·17	118·45	105	138·75	133·65	90	155·14	131·21	100	128·30	117·50	90	0·19	0·09
2012	171·45	120·49	160	174·67	131·93	160	167·33	108·28	155	169·36	130·49	150	173·30	105·49	165	0·83	0·53
2013	149·85	70·38	142·5	153·83	77·31	140	145·87	62·77	147·5	157·21	71·68	150	139·55	67·53	140	0·91	0·03
2014	169·79	105·28	140	167·50	111·62	140	172·08	98·96	200	184·00	110·94	220	149·90	93·78	125	0·64	0·007
2015	213·54	179·04	145	234·75	194·13	155	192·33	160·57	140	263·43	201·98	210	143·70	107·95	120	0·15	<0·001

^* P value from Mann–Whitney U test comparing between boys and girls.

^† P value from Mann–Whitney U test comparing between urban and rural areas.

^‡Number of children for both urban and rural areas was 120 subjects in 2007.