TABLE 2.

Serum concentrations of 25(OH)D and PTH by demographic, dietary, and behavioral factors in 418 participants with knee osteoarthritis¹

		25(OH)D, μg/L		PTH, pg/mL
Characteristics	n	Values	P	Values	P
Age, y			<0.001		0.55
<63	241	24.3 ± 10.0		55.2 ± 27.0
≥63	247	28.0 ± 10.1		53.7 ± 26.1
Sex			0.05		0.18
Male	258	25.3 ± 9.4		52.9 ± 23.7
Female	230	27.2 ± 11.0		56.2 ± 29.4
Race			<0.001		0.001
Non-Hispanic white	360	27.8 ± 10.0		52.2 ± 25.2
Other	128	21.5 ± 9.6		60.9 ± 29.3
Place of residence			0.01		0.43
Baltimore, MD	108	24.6 ± 9.4		56.9 ± 31.9
Pawtucket, RI	139	26.9 ± 10.6		53.8 ± 25.8
Columbus, OH	134	28.0 ± 10.6		51.8 ± 24.4
Pittsburg, PA	107	24.5 ± 9.6		56.2 ± 24.1
BMI, kg/m2			<0.001		0.01
<25	84	29.1 ± 10.4		48.0 ± 25.2
25–29.9	185	28.1 ± 10.1		53.3 ± 24.8
≥30	219	23.5 ± 9.6		57.9 ± 28.0
Meeting physical activity guidelines			0.006		0.23
No	336	25.4 ± 10.3		55.4 ± 27.8
Yes	152	28.1 ± 9.9		52.3 ± 23.5
Alcohol consumption, g/d			0.32		0.42
<14	416	26.0 ± 10.0		54.8 ± 27.1
≥14	69	27.4 ± 11.4		52.0 ± 23.3
Cigarette smoking			0.32		0.48
Former or current smokers	219	26.7 ± 10.8		55.4 ± 27.6
Nonsmokers	265	25.8 ± 9.8		53.7 ± 25.8
Vitamin D intake from food and supplement, IU/(d · 1000 kcal)			<0.001		0.02
<258	245	22.9 ± 9.3		57.3 ± 26.8
≥258	243	29.6 ± 10.1		51.6 ± 26.1
Use of vitamin D supplement, IU/d			<0.001		0.03
<400	213	22.1 ± 9.0		57.5 ± 26.7
≥400	275	29.4 ± 10.0		52.1 ± 26.2
Calcium intake from food and supplement, mg/(d · 1000 kcal)			<0.001		0.06
<612	245	23.6 ± 9.6		56.7 ± 27.0
≥612	243	28.9 ± 10.2		52.2 ± 26.0
Season of blood draw			0.02		<0.001
Summer	55	29.0 ± 9.9		60.4 ± 28.2
Fall	190	27.1 ± 10.4		49.1 ± 24.9
Winter	174	24.9 ± 10.2		54.5 ± 24.8
Spring	69	24.5 ± 9.5		64.3 ± 30.6
History of knee injury or surgery			0.47		0.56
No	202	25.8 ± 10.5		55.2 ± 27.8
Yes	286	26.5 ± 10.1		53.7 ± 25.7

¹Values are presented as means ± SDs unless otherwise indicated. OA, osteoarthritis; PTH, parathyroid hormone; 25(OH)D, 25-hydroxyvitamin D.