Table 3.
Multivariate-Adjusted Differences in Intact Parathyroid Hormone
| Variable | Difference in PTH (pg/ml) | 95% CI | P for Trend |
|---|---|---|---|
| BMI (kg/m2) | |||
| <21 | 0.4 | (−1.6 to 2.3) | |
| BMI 21–22 | Ref | ||
| 23–24 | 1.0 | (−0.8 to 2.8) | |
| 25–26 | 0.5 | (−1.5 to 2.4) | |
| 27–29 | 2.0 | (0.2 to 3.9) | |
| 0.05 | |||
| Smoking | |||
| Never | Ref | ||
| Past | −0.2 | (−1.6 to 1.2) | |
| Current | −4.8 | (−7.7 to −1.9) | |
| 1–14 cig/day | −4.1 | (−7.7 to −0.5) | |
| 15–34 cig/day | −6.4 | (−11.2 to −1.7) | |
| Total Calcium Intake | |||
| Quartile 1 | Ref | ||
| Quartile 2 | −0.9 | (−2.7 to 0.9) | |
| Quartile 3 | −0.5 | (−2.4 to 1.4) | |
| Quartile 4 | −1.3 | (−3.4 to 0.7) | |
| 0.07 | |||
| Total Vitamin A Intake | |||
| Quartile 1 | Ref | ||
| Quartile 2 | −1.2 | (−3.0 to 0.5) | |
| Quartile 3 | −0.5 | (−2.3 to 1.2) | |
| Quartile 4 | −1.9 | (−3.7 to −0.07) | |
| 0.01 | |||
| Season of Blood Draw | |||
| Summer | Ref | ||
| Winter | 3.2 | (1.3 to 5.1) | |
| Spring | 3.0 | (1.1 to 4.8) | |
| Fall | 1.7 | (−0.03 to 3.4) | |
| Plasma 25(OH)D | |||
| Quartile 1 | Ref | ||
| Quartile 2 | −2.5 | (−4.2 to −0.8) | |
| Quartile 3 | −3.1 | (−4.8 to −1.3) | |
| Quartile 4 | −4.5 | (−6.3 to −2.7) | |
| <.001 | |||
| Plasma Phosphorus | |||
| Quartile 1 | Ref | ||
| Quartile 2 | −3.7 | (−5.4 to −2.0) | |
| Quartile 3 | −3.8 | (−5.5 to −2.2) | |
| Quartile 4 | −4.1 | (−5.8 to −2.4) | |
| <.001 | |||
| Plasma Calcium | |||
| Quartile 1 | Ref | ||
| Quartile 2 | −1.7 | (−3.3 to −0.1) | |
| Quartile 3 | −3.0 | (−4.9 to −1.2) | |
| Quartile 4 | −5.3 | (−7.0 to −3.6) | |
| <.001 | |||
Note: The multivariate regression model was adjusted for age, race, phosphorus intake, animal protein intake, creatinine, and all other covariates listed in the table. Tests for trend were not performed for categorical or binary variables.