CONTEXT:

Black women have lower 25-hydroxyvitamin D [25(OH)D] and higher PTH than white women. Recent evidence implicates PTH in adverse cardiovascular outcomes.

OBJECTIVE:

The objective of the study was to determine whether PTH increases at lower 25(OH)D levels (the threshold) in black compared with white women.

DESIGN:

Healthy black and white women, aged 20-80 yr were recruited to participate in a cross-sectional study of body-composition in black and white women. Measurement of serum 25(OH)D and PTH were carried out.

SETTING:

The study was a convenience sample recruited from a community setting.

PATIENTS:

Healthy black and white women were recruited by advertising and a direct mail campaign in a comparative study of body composition. Age ranged from 20-to 80 yr. There were 148 black and 129 white premenopausal participants and 87 black and 139 white postmenopausal participants.

MAIN OUTCOME:

The main outcome was to determine whether the threshold for 25(OH)D/PTH differs in black and white women.

RESULTS:

A threshold of 37 nmol/liter (95% confidence interval 35-40) was found for black and 59 nmol/liter (95% confidence interval 56-63) for white women. These two values were significantly different (P < 0.001).

CONCLUSIONS:

Black women have an increase in serum PTH at a lower 25(OH)D level than white women. Negative health outcomes of higher PTH should be investigated in black women.