Ethnic origin and serum levels of 1alpha,25-dihydroxyvitamin D3 are independent predictors of coronary calcium mass measured by electron-beam computed tomography.
BACKGROUND
Blacks have been found to have lower amounts of coronary calcium as well as higher levels of the osteoregulatory steroid 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] than whites. We sought to determine if racial differences in coronary calcium mass could be explained by differences in serum levels of 1,25(OH)2D3.


RESULTS
We evaluated standard coronary risk factors, quantified coronary calcium mass with electron-beam computed tomography (EBCT), and measured serum 1,25(OH)2D3 with radioimmunoassay in 283 high-risk subjects (51 [180%] black, 232 [82%] white). Black subjects had lower masses of coronary calcium than whites (14 versus 47 mg; P=.003). Serum 1,25(OH)2D3 levels were slightly higher in blacks (41 versus 38 pg/mL; P=.05). Log 1,25(OH)2D3 levels were inversely proportional to log-transformed calcium mass (r=-.19; P=.001) in both races. Multivariate linear regression demonstrated that both black race (P=.02) and 1,25(OH)2D3 levels (P=.007) contributed inversely and independently to coronary calcium mass. However, an interaction term of racex1,25(OH)2D3 did not significantly contribute to coronary calcium mass, indicating that other undetermined factors in addition to 1,25(OH)2D3 are responsible for ethnic differences in coronary calcium mass.


CONCLUSIONS
Both black race and serum levels of 1,25(OH)2D3 are independent negative determinants of coronary calcium mass. Nevertheless, diminished amounts of coronary calcium in blacks are not accounted for by higher 1,25(OH)2D3 levels.
Doherty
T M
TM
Department of Medicine, Harbor-UCLA Medical Center, and the Saint John's Cardiovascular Research Center, Torrance, Calif 90502, USA.
Tang
W
W
Dascalos
S
S
Watson
K E
KE
Demer
L L
LL
Shavelle
R M
RM
Detrano
R C
RC
D000368:Aged; D001158:Arteries / Q000378:metabolism; D044383:Black People; D002117:Calcitriol / Q000097:blood*; D002118:Calcium / Q000378:metabolism*; D003331:Coronary Vessels / Q000378:metabolism*; D003710:Demography; D005260:Female; D005544:Forecasting; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D012307:Risk Factors; D014054:Tomography / Q000379:methods*; D044465:White People
D002117:Calcitriol; D002118:Calcium