HOW CAN WE PROTECT PEAK BONE MASS AND FUTURE BONE HEALTH FOR ADOLESCENT WOMEN? - BY SUPPORTING OVULATION AND AVOIDING COMBINED HORMONAL CONTRACEPTION USE

aCentre for Menstrual Cycle and Ovulation Research, Endocrinology and Metabolism, University of British Columbia, Vancouver, Canada. Received on April 30, 2017. HOW CAN WE PROTECT PEAK BONE MASS AND FUTURE BONE HEALTH FOR ADOLESCENT WOMEN? – BY SUPPORTING OVULATION AND AVOIDING COMBINED HORMONAL CONTRACEPTION USE Como podemos proteger o pico de massa óssea e a saúde óssea futura em mulheres adolescentes? – Mantendo a ovulação e evitando o uso de pílulas contraceptivas combinadas


OVULATORY CYCLES, PEAK BONE MASS, AND BONE HEALTH
Does bone change relate to maturation in ovulation development as well as to regular cycles? This has not been well investigated, but one small prospective study showed ovulation took at least 10 months post-menarche to first begin 4, and even more than menarche, was temporally associated with whole body BMD gain ( Figure 1). 4 Furthermore, a meta-analysis of women from their teens through their 30s, showed that those with more versus fewer ovulation-disturbed cycles had almost one percent per year more negative spinal BMD changes (-0.86%/y [95%CI -1.68--0.04] p=0.04). 5 Why? Because the normal increase and decrease of estradiol levels within each menstrual cycle causes some bone resorption that progesterone can counterbalance by stimulating osteoblastic bone formation. 11

TREATMENT OF TEEN MENSTRUAL CYCLE-RELATED DISTURBANCES
Menstrual cramps (dysmenorrhea) are common in adolescent women and effectively treated by intense anti-prostaglandin therapy staying ahead of the pain 12. Acne is also prevalent in young women around menarche, gets better with time, and can usually be controlled by avoiding facial oil-based exposures, eating a healthy diet, and use of over-the-counter topical drying agents. A few women will get very heavy flow related to estrogen excess and an ovulation. As mentioned, irregular cycles are the norm for at least the first post-menarche year, and a few normal young women will skip cycles for months at a time for several more years. But these normal maturational issues are often inappropriately "treated" with combined hormonal contraception 13 . As pharmacological doses of synthetic estrogen and progestin, CHC causes regular withdrawal flow but actually "covers up" rather than facilitating reproductive maturation or resolving the underlying issue.
Most of the cycle, flow, cramps, and skin-related problems of adolescents are related to an imbalance: too much estrogen and too little progesterone. Therefore, cyclic progesterone therapy (oral micronized progesterone, 300 mg at bedtime for 14 days/cycle) is an ideal initial or transitional treatment. However, this notion has only been scientifically tested as cyclic medroxyprogesterone (10 mg for 10 days/month) for hypothalamic amenorrhea, oligomenorrhea, regular cycles with anovulation or short luteal phases in normal-weight women ages 20-35 years, 14 in whom it caused a significant increase in spinal BMD (+2.0%/y versus -2.0%/y in placebo). My clinical experience is that cyclic progesterone plus social, emotional, and nutritional support is highly effective for maturation of both ovulation and bone.

COMBINED HORMONAL CONTRACEPTION USE AND ACHIEVING AND MAINTAINING PEAK BONE MASS
Increasing evidence shows that use of CHC during adolescence may be related to less positive gain to PBM 13 . This may occur because the supra-physiological dose of ethinyl estradiol (needed to prevent pregnancy), suppresses bone modeling that is necessary to achieve PBM. Furthermore, a recent random effects meta-analysis showed that more negative rates of two-year spinal BMD change (-0.02 [95%CI -0.03--0.01] g/cm 2 ; p=0.0007) occurred for ~900 women ages 12-19 years, using CHC versus non-using controls (Goshtasebi, 2017, submitted). These are yet a further reason to use cyclic progesterone therapy 15 rather than CHC for symptomatic adolescents with "funny cycles," cramps, acne, or heavy flow.

CONCLUSION
Adolescent maturation requires increased attention, although we are all aware that adolescence is a time of growth and maturation. Almost all cycle-related problems in adolescents seem to be reflexly treated with CHC, meaning with high-dose, suppressive, exogenous hormones. In particular, we need to carefully examine adolescent maturation related to the reproductive and musculoskeletal systems. With the perspective that there is a unique, once-in-a-lifetime window of opportunity to develop normally ovulatory cycles and optimal PBM, disturbances of these need to first be detected, and then treated physiologically. Cyclic progesterone treatment versus CHC, however, still requires randomized, controlled, trial examination for its effects on adolescent reproductive problems and bone change. We must exercise caution before prescribing CHC for adolescent problems, given that other treatments are effective, and for birth control, given that other options for heterosexually active teens at risk of pregnancy are also available. 16

Funding
This study did not receive funding.