Functional hypothalamic amenorrhoea (FHA) occurs when the brain stops sending the necessary signals (LH and FSH) to the ovaries, preventing hormone production and ovulation.
Health Implications
Low oestrogen levels in FHA increase the risk of osteoporosis and potentially cardiovascular disease in the long term.
Causes
The causes of FHA are multifactorial, including:
- Low energy availability
- Carbohydrate availability
- Training load
- Psychological stress
- Genetics
FHA vs. Premature Ovarian Insufficiency (POI)
FHA differs from premature ovarian insufficiency (POI), where the ovaries run out of follicles. In POI, hormone replacement therapy (HRT) is clearly recommended until the average age of menopause.
HRT in FHA
The decision to use HRT in FHA is more complex. The primary goal should be to restore menstrual cycles through lifestyle changes. If HRT is used, it should be considered a temporary measure until natural cycles resume.
When to Use HRT
The use of HRT depends on individual circumstances. According to UK NICE guidelines by Dr. Nicky Keay, HRT is recommended if there have been two stress fractures or if Z-scores are below -1 (indicating bone density below the 14th percentile for age).
Topical vs. Oral Oestrogen
For bone density benefits, oestrogen must be topical (e.g., gel or patch). Research shows that topical oestrogen improves bone density in FHA, whereas oral oestrogen, including the pill, does not. This is due to oral oestrogen’s impact on growth hormone and cortisol, and its different molecular structure compared to natural oestrogen (17-beta oestradiol).
The Pill and Menstrual Cycles
The pill does not restore natural menstrual cycles and further suppresses LH and FSH. Topical oestrogen, being 17-beta oestradiol, bypasses the liver and has less impact on other hormones. Low-dose topical oestrogen does not prevent the restoration of menstrual cycles and does not provide contraception, meaning conception could occur when ovulation first returns before a period.
Long-term FHA
For those with long-term FHA, it is never too late to try to regain natural menstrual cycles and hormone production. If this does not occur, topical oestrogen is generally indicated for bone health and other benefits, similar to POI.
Medical Review
If you have lost your period for more than three months, it is important to seek medical review. 🙏