London five-year-old begins hormone-blocking treatment after rare early puberty diagnosis

A five-year-old girl in London is undergoing hormone-blocking treatment after being diagnosed with central precocious puberty at just 10 months old, highlighting the challenges and emotional impact of this rare condition.

A five-year-old London girl is receiving hormone-blocking treatment after doctors found she had begun puberty at just 10 months old, a rare case that has left her mother focused on protecting her childhood while managing a condition that can advance far earlier than normal.

Siena’s mother, Sophie Dumas, initially did not realise anything was wrong. The concern was first raised by a health visitor, who noticed swollen tissue in the infant’s chest and advised further testing. After a series of assessments, Siena was diagnosed with central precocious puberty, or CPP, a disorder in which the brain triggers puberty too early.

The diagnostic process was demanding for the family. Siena underwent hormone tests, repeated blood draws and X-rays to determine her bone age, a measure doctors use to see whether a child’s skeleton is maturing too quickly. She also had an MRI scan to rule out brain abnormalities that can sometimes be linked to the condition. According to medical guidance from the Mayo Clinic and MedlinePlus Genetics, that combination of blood work, imaging and growth assessment is standard when doctors suspect early puberty.

Siena is now being treated with regular injections that suppress the hormones driving pubertal development. Doctors typically use GnRH analogue therapy for children with progressive CPP to slow or pause puberty until they reach a more typical age, after which normal development usually resumes. The Mayo Clinic says treatment commonly continues until around the usual age of puberty, depending on the child’s growth and medical response.

Although CPP is not usually life-threatening, specialists warn it can affect height because growth plates may close too soon, leaving children shorter as adults than they might otherwise have been. Dumas is also worried about the emotional toll. Siena has already faced teasing at school because of changes in her appearance, and her mother says she is determined to preserve the rituals and imagination of early childhood, from fairy stories to Disney characters.

Doctors and families dealing with CPP often look not only at growth but also at fertility and long-term wellbeing. In Siena’s case, options such as egg freezing may be considered later if there are concerns about future fertility, though that would depend on how the condition develops over time. For now, the priority is simple: keep the child safe, supported and as much a child as possible.