The effects of age and ethnicity on the circadian variation of catecholamines and cortisol in employed women.

Background: Women employed outside the home in urban settings must adapt to changing circadian microenvironments. The pattern and extent of vasoactive hormone responses to these changes may depend upon age and ethnic background. The purpose of this study was to evaluate the effects of age and ethnicity on the circadian variation of urinary norepinephrine, epinephrine, and cortisol excretion across work, home and sleep microenvironments.

Methods: The subjects of the study were 95 women (38 European-American, age = 35.4 ± 7.4; 28 African-American, age = 33.4 ± 7.9; 12 Asian-American, age = 36.7 ± 9.3 and 17 Hispanic-American age = 31.6 ± 10.9) employed as secretaries, lab technicians or office supervisors in New York City. Variation in the hormones across the microenvironments was evaluated using repeated measures ANCOVA with age group (18-29.9; 30-39.9; 40-49.9) and ethnicity as fixed factors.

Results: The results show that for norepinephrine and epinephrine, work excretion rates are substantially higher than sleep rates (p < .001), and for epinephrine home rates were higher than sleep rates (p < .001). Work and sleep cortisol excretion rates were also significantly higher than the rate at home, consistent with cortisol's circadian rhythm. (p < .002). Women in their twenties had substantially lower norepinephrine excretion rates than women over 30 (p < .04). There were also ethnic differences in norepinephrine (p < .04) and epinephrine (p = .11) output with Asian-American women having the lowest and African-American women having the highest rates. This variation is likely related to the ethnic variation in weight. There was no significant variation in cortisol excretion with age or ethnicity.

Conclusion: The circadian rates of norepinephrine excretion differ by age and that of both catecholamines differ by ethnicity among women working outside the home. It is speculated that the age variation in norepinephrine may contribute to the development of vasomotor symptoms.