Urinary hormone levels during the natural menstrual cycle: the effect of age

Abstract
A number of studies have identified hormonal changes in women during their reproductive lifespan, many focusing upon changes in women over the age of 40 years. The present study has determined the effect of increasing age on hormone levels over three decades. Daily early morning urine samples were assayed for estrone-3-glucuronide (E3 G), pregnanediol-3-glucuronide (P3 G), testosterone-17-glucuronide (T17 G), FSH and LH. An examination of the validity of using creatinine as a volume adjuster in urine samples formed an integral part of the analysis. Volunteers were healthy women who had regular (25-35 days) cycles, were not taking oral contraceptives, hormone therapies or any other medication. Three age groups were compared: 20-29 years (n=13), 30-39 years (n=9) and 40-49 years (n=13). Statistical analyses were carried out using two-way ANOVA and post hoc t-tests. Creatinine excretion, despite revealing no cycle-related variation in any age group, showed a decline with increasing age. Creatinine output was significantly lower in the 40-49 years age group in all phases of the cycle than in the 20-29 and 30-39 groups (P

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