Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
Inverse Relationship Between 25-Hydroxyvitamin D and Parathyroid Hormone Observed in the General Population but Not Among Rheumatoid Arthritis Patients.
Broder1, Anna R., Skversky2, Amy, Melamed3, Michal L., Tobin4, Jonathan N., Hardin5, John A., Putterman3, Chaim
Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY
Montefiore Medical Center, Bronx, NY
Albert Einstein College of Medicine, Bronx, NY
Albert Einstein College of Medicine/CDN Network, New York, NY
Albert Einstein Coll of Med, Bronx, NY
Background/Purpose:
Vitamin D deficiency and insufficiency are defined as 25-hydroxyvitamin D (25OHD) levels below 20 ng/ml and 30 ng/ml, respectively, based on data from the general population demonstrating that parathyroid hormone (PTH) levels normalize (below 65 pg/ml) at 25OHD concentrations above 30 ng/ml. Our hypothesis is that the relationship between 25OHD and PTH is altered in rheumatoid arthritis (RA) due to chronic inflammation and corticosteroid use. We studied the relationship between 25OHD and PTH using both the National Health and Nutrition Examination Surveys (NHANES) 2003–2006 and RA patients from a large tertiary care center.
Methods:
For the NHANES cohort and for the tertiary care center cohort we included all adult participants with recorded values for 25OHD and PTH. Participants from both cohorts were excluded if their estimated glomerular filtration rate was < 50 ml/min/1.73 m2, because of the known altered relationship between 25OHD and PTH in chronic kidney disease. In the NHANES we compared participants with RA and participants without arthritis, based on self-report. Linear regression adjusted for age, gender, race/ethnicity and body mass index (BMI) was used for the NHANES cohort within each 25OHD interval (< 10, 10 to 20, 20 to 30, and >30 ng/ml). We constructed Kernel-weighted local polynomial smoothing curves for the RA cohort from our center.
Results:
In the NHANES cohort, there were 363 participants with RA, and 5995 without arthritis. In the no-arthritis group the relationship between PTH and 25OHD within each stratum of 25OHD was similar to what was previously described in the general population. However, there was no statistically significant relationship between PTH and 25OHD in any of the strata among RA participants (Table 1). Similarly, among 47 RA patients from the tertiary care center who satisfied the inclusion criteria, PTH levels normalized at 25OHD levels slightly above 10 ng/ml and remained fairly constant at all 25OHD levels (Figure 1).
Table 1. Linear regression model showing the change in PTH (95% CI) per 1 ng/ml change in 25OHD within each 25OHD interval (ng/ml): < 10, 10 to 20, 20 to 30, and >30, adjusted for age, gender, race/ethnicity, and BMI
| RA (363 observations, subpopulation 4460045) | No arthritis (5995 observations, subpopulation size 91951415) | |
|---|---|---|
| For 25OHD < 10 ng/ml, change in PTH, pg/ml (95% CI) | 0.08 (-4.3, 4.4) | -2.9 (-5.1, -0.7) |
| p-value | 0.969 | 0.011 |
| For 25OHD >= 10 ng/ml and < 20 ng/ml, change in PTH, pg/ml (95% CI) | -1.2 (-3.0, -0.5) | -0.8 (-1.3, 0.3) |
| p-value | 0.154 | 0.003 |
| For 25OHD >= 20 ng/ml and < 30 ng/ml, change in PTH, pg/ml (95% CI) | -0.1 (-1.0, 0.77) | -0.1 (-0.5, 0.2) |
| p-value | 0.796 | 0.5 |
| For 25OHD >= 30 ng/ml, change in PTH, pg/ml (95% CI) | -0.3 (-0.9, 0.2) | -0.2 (-0.3, -0.1) |
| p-value | 0.19 | 0.003 |
Figure 1. Polynomial curve for RA from a large tertiary care center (n=47)
Conclusion:
The relationship between PTH and 25OHD is altered in RA compared with the general population. This finding has important implications for future clinical trials and for optimizing vitamin D replacement in RA.
To cite this abstract, please use the following information:
Broder, Anna R., Skversky, Amy, Melamed, Michal L., Tobin, Jonathan N., Hardin, John A., Putterman, Chaim; Inverse Relationship Between 25-Hydroxyvitamin D and Parathyroid Hormone Observed in the General Population but Not Among Rheumatoid Arthritis Patients. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1693
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