Never having had a period by the age of 15 or 16 is an uncommon reason to see a doctor, but very different things can lie behind it: from a simple developmental delay to a chromosomal condition. A study that reviewed a full year of clinical activity across the Japanese prefecture of Fukushima concludes that the most frequent cause of primary amenorrhoea is Turner syndrome, accounting for 43.4% of cases.
The paper, published in Fukushima Journal of Medical Science, is based on questionnaires sent to the centres affiliated with the Fukushima Obstetrics and Gynecology Association between October 2021 and September 2022. The authors collected data on patients aged 15 to 45 and did not simply count cases: they wanted to know who looks after these patients, what the underlying causes are and how the condition is treated. The comparison with secondary amenorrhoea — periods that stop after they have started — proved revealing: there the leading cause was polycystic ovary syndrome, at 47.7%. In other words, periods that never arrive and periods that stop are not the same problem and usually do not share the same origin — worth remembering before protocols are merged.
In the case of Turner syndrome, the study also sketches how care actually works in daily practice. Half of the cases (50.6%) were followed up at a general hospital, almost half of the patients had associated complications and every single one of them was receiving hormone medication. The most widely used preparations were transdermal oestrogen (43%), followed by combined oestrogen tablets (40%). Among progestins, the most commonly prescribed was dydrogesterone (43%), ahead of medroxyprogesterone (37%). These are routine-use figures, not clinical-trial data, and they work as a mirror for other health systems that want to compare their own regimens.
The message the authors draw is mainly organisational. They argue that obstetrics and gynaecology departments must build long-term follow-up systems and work alongside other health professionals, paediatric services and internal medicine, because managing pathological amenorrhoea is a lifelong task — and that clashes with a model of care that is often designed around one-off episodes. Finding Turner syndrome in adolescence does not close the case: it opens a schedule of reviews and treatments that will accompany the patient for decades, and that kind of continuity needs someone to take responsibility for it.
For families, the practical takeaway is twofold. First, primary amenorrhoea deserves a full aetiological work-up, because a chromosomal condition may be behind it and not merely a delay. Second, the hormone treatment these patients receive is neither cosmetic nor a minor detail: in the study every one of them was on it, and the authors place it at the centre of long-term care for these women.
It is worth remembering the study’s limits: it is a questionnaire survey, confined to a single prefecture and focused on clinical activity rather than population prevalence. It cannot be used to extrapolate exact figures to other countries or other health systems. Even so, it provides something often missing from the Turner syndrome literature: a picture of how care is really delivered, away from the big referral centres and with everyday resources.
Source: A survey of pathological amenorrhea in Fukushima prefecture, with a focus on Turner syndrome. Yamaguchi A, Yoshida-Komiya H, Takahashi T, Noguchi M, Fujimori K. Fukushima Journal of Medical Science 2026; published online 10 October 2026. DOI: 10.5387/fms.26-00025.
Read the publication: https://doi.org/10.5387/fms.26-00025 · PubMed: PMID 42864032
