Table 1.

Select characteristics by serum 25OHD^a status in children ages 1 to 18 years in the National Health and Nutrition Examination Survey 2005-2006 (N=3,310)

	25OHD
	Inadequate (<20 ng/mLb) (n=1,204)	Adequate (20 to <30 ng/mLb) (n=1,463)	Optimal (≥30 ng/mLb) (n=643)	P valuec
Age				<0.001
1-8 y	9.4 (0.8)	48.4 (2.7)	42.2 (2.7)
9-18 y	30.2 (1.9)	46.5 (1.9)	23.2 (1.5)
Sex				0.03
Male	18.4 (1.4)	48.2 (2.2)	33.4 (2.6)
Female	26.0 (1.6)	46.3 (2.6)	27.7 (2.0)
Race/ethnicity				<0.001
Non-Hispanic white	10.1 (1.6)	48.8 (2.2)	41.1 (1.6)
Non-Hispanic black	58.4 (1.8)	35.6 (2.1)	5.9 (1.0)
Mexican American	31.6 (1.7)	51.0 (2.1)	17.9 (1.7)
Other	30.0 (3.2)	49.2 (4.6)	20.8 (2.9)
Weight category (n=2,789)				<0.001
Underweight (<5th percentile)	25.2 (8.1)e	29.8 (7.8)	45.0 (11.2)
Healthy (5th to 84.9th percentile)	20.1 (1.1)	47.3 (1.5)	32.5 (1.5)
Overweight (85th to 95th percentile)	26.0 (2.6)	47.7 (3.0)	26.3 (3.6)
Obese (>95th percentile)	36.8 (4.0)	44.6 (3.7)	18.6 (3.7)
Poverty-to-income ratio				<0.001
<130%	30.9 (1.5)	45.8 (2.3)	23.3 (2.0)
130% to <350%	20.6 (1.3)	49.5 (2.3)	30.0 (2.1)
≥350%	15.3 (1.8)	46.1 (2.5)	38.7 (2.5)
Seasonf (n=3,167)				0.33
Winter	21.7 (1.6)	49.3 (2.1)	29.0 (1.0)
Summer	22.3 (1.4)	45.8 (1.8)	31.9 (2.1)
Latitude g				0.17
South	20.1 (1.9)	50.8 (2.1)	29.1 (1.3)
North	22.9 (1.3)	45.7 (1.9)	31.4 (1.7)

^a25OHD=25-hydroxyvitamin D.

^bTo convert ng/mL 25OHD to nmol/L, multiply ng/mL by 2.496. To convert nmol/L 25OHD to ng/mL, multiply nmol/L by 0.4. 25OHD of 20 ng/mL=49.92 nmol/L.

^cAnalyzed with Rao-Scott χ2 test.

^dSE=standard error.

^eThe relative SE is >30%, this estimate is unreliable.

^fData collected during May 1 through October 31 (summer) and November 1 through April 30 (winter).

^gSouth is <35° and North is ≥35°.