Precocious puberty: signs, causes and treatment of early puberty

Puberty is the stage when a child's body changes as they become an adult. The NHS says it is normal for it to start at any time from 8 to 14 years old, and that signs starting before 8 could be early puberty. Typical early signs are hair growing under the arms and in the genital area, breast development in girls, and larger testicles or penis in boys.

Cambridge University Hospitals explains that girls on average start the changes of puberty at around 10 to 11 years old, with a wide range, and that the first clear sign is breast budding. Periods usually begin 2 to 3 years after the breast changes. Puberty usually progresses over 2 to 3 years.

The same leaflet notes that the age at which girls start puberty has been gradually getting earlier, and estimates that 5 to 10% of girls start between 7 and 8. A start at that age can be a normal variation rather than a disorder.

The NHS says treatment is usually only needed if early puberty is causing physical or emotional problems, and may involve treating an underlying condition or medicine that can delay puberty. Kingston and Richmond NHS Foundation Trust says medication is usually only recommended if early puberty is thought likely to cause problems such as short stature or early periods that cause distress.

Cambridge University Hospitals explains that the treatment licensed for children is a regular intramuscular injection that blocks the GnRH signal to the pituitary gland, available in 3-monthly and 6-monthly versions. Treatment is usually effective at stopping further progress and early periods, and can help preserve final height, with the younger child more likely to benefit. Some girls notice breast development reduce or stop growing, while pubic and underarm hair usually stays.

The leaflet says there are no known serious short or long-term side effects, that injection site redness, bruising and transient headaches can occur, that spotting can occur initially, and that there is no evidence of an effect on future fertility. Treatment usually continues until the girl reaches about 10 or 11, after which puberty resumes at a normal rate. The decision is agreed between the family and the endocrine doctor.

Puberty starts when part of the brain called the hypothalamus releases a hormone, gonadotrophin releasing hormone (GnRH), which prompts the pituitary gland to release luteinising hormone and follicle stimulating hormone. These tell the ovaries or testicles to make sex hormones. In central precocious puberty this chain starts too soon.

Cambridge University Hospitals says in most cases there is no underlying cause: the brain sends pubertal signals earlier than it should. It is more likely in some ethnic groups or if another family member had early puberty, due to shared genetic factors. Rarely, it can be a sign of another medical condition, particularly if puberty starts very early, for example before age 6, or in a child with other illnesses.

The NHS lists conditions that can sometimes affect puberty timing, including problems with the ovaries, testicles or hormones, damage to the brain from surgery, radiotherapy, infection or severe head injury, and certain long-term conditions. The Endocrine Society, a US body, also distinguishes a rarer peripheral form, where sex hormones come from the ovaries, testicles or adrenal glands, or from external exposure such as hormone creams.

Kingston and Richmond NHS Foundation Trust describes how early puberty may look. In girls the most obvious sign is breast development, along with pubic and underarm hair, a growth spurt, vaginal discharge or periods, monthly tummy cramps, greasy hair, acne and body odour. In boys, signs are a larger penis and testicles, a deeper voice, muscles and hair growth, spots and a growth spurt.

Parents may also notice mood changes that resemble those of teenagers, including irritability and tearfulness. Early vaginal bleeding without breast development, rapid height growth, or any pubertal sign in a boy before 9 are reasons to be seen without delay. The leaflet advises booking a GP appointment if these changes appear before a daughter is 8 or a son is 9.

The NHS says a GP may recommend blood tests to check hormone levels, an X-ray of the wrist to estimate adult height, and an ultrasound or MRI scan to look for problems inside the body, usually only if a condition could be causing the early puberty. Kingston and Richmond NHS Foundation Trust adds that an abdominal ultrasound may look at the womb and ovaries in girls and an MRI of the brain is used in certain situations.

At the children's endocrine clinic, a doctor will examine the child to see how far puberty has progressed, with a chaperone present, and the child will be weighed and measured. Parents' heights are usually measured to help predict growth. Cambridge describes an LHRH test, in which a small intravenous cannula is placed, a synthetic form of GnRH is given and the hormone response is measured over an hour, to establish whether puberty is truly under way.

If puberty has not truly started, no treatment is needed and the child is simply reviewed.

Cambridge University Hospitals points out two main concerns even when no medical cause is found. First, adult height can be shorter in some girls who are already short when puberty starts, or if it starts very early, because bones mature faster and the growth plates fuse sooner.

Second, children may feel self-conscious about looking different from friends. In many cases this can be handled with reassurance and practical support at school, such as discreet changing arrangements or a sports bra. Early periods can also be distressing for a young girl.

Parents may feel anxious too. The leaflet encourages open, honest conversations using proper words for body parts, and reminds families that endocrine nurses and psychologists can help.

Explaining what is happening in age-appropriate language, and stressing that the body is doing something normal that older children also experience, can reduce fear. Younger children may need stories and play to express worries. Talking to teachers in advance helps with changing rooms and sport.

Children who are treated need preparation for injections. Cambridge University Hospitals suggests explaining that an injection may hurt a little but will be quick, and says ice packs, cold spray, a vibrating device or local anaesthetic cream can help.

Charity and professional resources include the Child Growth Foundation and the British Society of Paediatric Endocrinology and Diabetes, which both signpost information for families.

See a GP if signs of puberty begin before 8 in a girl or 9 in a boy. Seek prompt advice for very early signs, rapid growth, vaginal bleeding without breast development, or when a boy is affected, since these are more likely to have a treatable cause. Headaches with vomiting, vision changes or unusual behaviour alongside early puberty need urgent assessment, through NHS 111 or A&E if severe.

The usual NHS route is GP, then referral to a general paediatric or children's endocrine clinic. Families who choose private paediatric endocrinology should ask for the results to be shared with the GP and, if treatment is started, who will monitor it. Facilities and approaches differ between hospitals.