What are the symptoms? One symptom common to both boys and girls is a premature growth spurt in height. Other symptoms include: In girls: breast developmentpubic hairarmpit haironset of periodsovary enlargementcysts on the ovaries. In boys: facial hairarmpit hairpubic hairpenis growthincreased masculinitytesticle enlargement. In both girls and boys, there can be body odour, acne and changes in behaviour. Isolated premature thelarche is a condition of young girls which involves only breast development, usually resolving after a year or two and does not require treatment. Premature adrenarche is a common condition between the ages of six and nine years of age with early activation of the adrenal glands involving pubic hair development, and increased rate of growth which only requires reassurance. What are the causes? Girls are more likely to be affected than boys. In some cases the cause of premature sexual maturation is not know. Many of the conditions that cause premature sexual maturation involve the early secretion of sex hormones. Some known causes of premature sexual development include: hormone-secreting tumour (gonadotropin-secreting tumour)severe hypothyroidism (underactive thyroid gland – see thyroid disorders for more information)congenital adrenal hyperplasiaMcCune-Albright syndrome (females)adrenal tumourtumour or lesion on the central nervous system or pituitary gland. How is it diagnosed? The doctor will ask about the child’s symptoms and medical history, and perform a physical examination. An assessment of puberty milestones and growth will be performed. An X-ray of the left wrist bone may be taken to assess if bone growth is normal for the child’s age. Referral to a specialist may be necessary and they may test levels of different hormones in the child and try to rule out any underlying conditions. How is it treated? The treatment for premature sexual development depends upon the cause. For children whose bone age is about the same as their actual age, and in whom no cause can be found, there is no treatment other than continued monitoring and reassurance. Psychological support may be needed for some children to deal with maturing a lot faster than their peers. Hormone suppressing medications work by halting or slowing sexual development. This treatment is often used in children whose bone age is older than their actual age. These medications not only stop sexual development and periods, they also halt the rapid bone growth that can result in the bones closing too soon. Metformin, a drug that is usually used to treat diabetes, has also been shown to be effective in delaying puberty. Inheritance patterns and prenatal diagnosis Inheritance patternsThis is dependent on the underlying diagnosis. Prenatal diagnosisNone. Is there support? Information and support in the UK for premature sexual maturation is provided by the Child Growth Foundation (see entry Restricted Growth).