Table 3.

Multivariate-adjusted differences in intact parathyroid hormone in non-Hispanic whites

Variable	Number	Difference in PTH (pg/ml)	95% CI	p, trend
Age (years)
<30	961	Referent		<0.01
30–39	643	2.6	1.3, 4.0
40–49	639	5.0	3.2, 6.9
50–59	583	5.9	4.0, 7.9
≥60	1,200	7.0	5.5, 8.4
Gender
Male	1,988	Referent
Female	2,038	2.2	0.6, 3.9
Body mass index (kg/m2)
<21	389	0.5	−1.6, 2.5	0.05
21–24	1,069	Referent
25–29	1,345	−0.5	−1.6, 0.7
30–34	699	0.4	−1.2, 2.0
≥35	470	1.8	−0.2, 3.8
Smoking
Never	1,681	Referent
Past	1,126	−0.4	−1.4, 0.7
Current	966	−5.3	−6.5, −4.2
Number of cigarettes per daya
<10	115	Referent		0.01
10–19	247	−2.8	−6.6, 1.0
≥20	484	−4.2	−7.6, −0.7
Dietary calcium intake (mg/day)
<558	1,006	Referent		0.02
558–836	1,007	−0.2	−1.9, 1.5
837–1,246	1,005	−0.8	−2.6, 1.0
≥1,247	1,008	−2.5	−4.8, −0.2
Serum 25(OH)D (ng/mL)
<20	983	Referent		<0.01
20–25	1,099	−3.3	−5.0, −1.6
26–30	964	−5.8	−7.0, −4.6
≥31	1,124	−7.9	−9.8, −6.0
Serum calcium (mg/dL)
<9.3	852	Referent		<0.01
9.3–9.4	849	−2.9	−5.3, −0.5
9.5–9.6	951	−3.6	−5.9, −1.2
≥9.7	1,374	−4.8	−6.7, −2.8
Serum phosphorus (mg/dL)
<3.5	957	Referent		0.01
3.5–3.7	898	−0.2	−1.8, 1.4
3.8–4.1	1,145	−0.7	−2.3, 0.9
≥4.2	1,026	−2.3	−4.0, −0.6
Serum uric acid (mg/dL)
<4.3	984	Referent		<0.01
4.3–5.1	972	2.2	0.2, 4.1
5.2–6.0	991	3.6	1.8, 5.5
≥6.1	1,078	4.9	2.7, 7.0
Serum retinol (μg/dL)
<49.2	994	Referent		0.06
49.2–58.7	1,004	−0.2	−1.9, 1.5
58.8–69.5	997	−0.2	−1.8, 2.1
≥69.6	1,005	−1.6	−3.4, 0.2

Covariates in the multivariate regression model are adjusted for age, gender, body mass index, smoking status, dietary calcium intake, dietary protein intake, season of blood draw, serum 25(OH)D, serum calcium, serum phosphorus, serum creatinine, serum uric acid, serum retinol, and fasting status

^aModel limited to participants who reported currently smoking