extrafluid is lost through menstruation. There is evidence that women can retain up
to two pounds of water in the luteal phase of their cycle for this purpose (Reid and
Yen 1981 ). The hormones of the RAAS in pre-menopausal women most likely act
as thefluid retention mechanism in the kidney to facilitate the potential repro-
duction, but since their primary role is related to blood pressure regulation, other
compensatory mechanisms (e.g., various actions of estrogen and progesterone)
must come into play to mitigate their blood pressure regulatory role (James and
Marion 1994 ). This“hidden adaptation”insures that blood pressure does not vary
inordinately from the follicular to luteal phase in reproductive age women as they
cycle each month, and in fact this hormonal arrangement provides a“protection”
from cardiovascular insults through the reproductive years (Pechere-Bertschi and
Table 8.1 Comparison of ambulatory blood pressure, PRA, and urinary aldosterone excretion
between the follicular and luteal phases of the menstrual cycle in a sample of employed women in
New York City (N= 47)
Characteristic Follicular phasea Luteal phasea pvalue
24-h blood pressure (mmHg) 117 ±2/73± 1 119 ±2/73±1NS
Work blood pressure (mmHg) 123 ±2/80± 1 124 ±2/80±1NS
Home blood pressure (mmHg) 121 ±2/77± 1 124 ±2/77±1NS
Sleep blood pressure (mmHg) 107 ±2/62± 1 108 ±2/63±1NS
Plasma renin activity(PRA)(ng/ml/h)b 1.45±0.14 2.66±0.25 0.001
24-h urinary aldosterone (μg/24 h) 4.99±0.53 9.17±1.1 0.001
Work urinary aldosterone (μg/24 h) 7.14±1.14 13.05±1.89 0.005
Home urinary aldosterone (μg/24 h) 4.22±0.78 8.62±1.39 0.004
Sleep urinary aldosterone (μg/24 h) 3.63±2.61 5.84±0.63 0.002Measures compared over 24 h and at work (11 a.m.–3 p.m.), home (approx. 6 p.m.–10 p.m.), and
during sleep (approx. 10 p.m.–6 a.m.). Values in the table are means±standard error
aLength of menstrual cycle is 28±3 days; follicular phase study day is 8±2, and luteal phase
study day is 22± 2
bMeasured from blood sample taken between 8 a.m. and 9 a.m.
Table 8.2 Selected
characteristics of the women
studied over their menstrual
cycle (N= 47)
Characteristic Mean±SD
Age (years) 36.0±7.9
Height (cm) 162.0±7.8
Weight (follicular) (kg) 66.2±12.0
Weight (luteal) (kg) 66.3±12.0
Education (years) 16 ± 2
Married (%) 31.9
Ethnicity (%)
European-American 40.4
African-American 38.3
Asian-American 4.3
Hispanic-American 17.08 Continuous Blood Pressure Variation: Hidden Adaptability 159