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Precocious puberty is the appearance of signs of pubertal development at an abnormally early age. In girls this has traditionally been considered to be 8 years, although guidelines from the USA have recommended that puberty be considered precocious only with appearance of breast development or pubic hair before age 7 in white girls and before age 6 in black girls. In boys, the onset of puberty before age 9 is considered to be precocious.
Precocious puberty is often a benign central process in girls but precocious puberty is rarely idiopathic in boys and early signs of puberty in boys are a particular cause for concern. Thelarche is the beginning of breast development and pubarche is the first appearance of pubic hair. Early appearance of these characteristics is more common than true precocious puberty.
Puberty occurs later in boys but spermarche occurs at about the same time as menarche and so reproductive capability is achieved at about the same age.
- The incidence and prevalence of precocious puberty depends on defining what is abnormal and the accurate assessment of the onset of puberty.
- Data from the USA indicate that 1 in 5,000 children are affected and that it is ten times more common in girls. Girls in the USA are generally maturing at an earlier age than they did 30 years ago.
- Racial differences are significant. An analysis of the National Health and Nutrition Examination Survey (NHANES) from the USA showed that black girls enter puberty earliest, followed by Hispanic and then white girls.
- Obesity also contributes to earlier puberty.
- In Europe earlier puberty has also been reported, particularly in warmer climates. Reports also suggest higher incidence of precocious puberty in girls adopted in Western Europe from underdeveloped countries.
Gonadotrophin-dependent precocious puberty (central precocious puberty (CPP))
Premature activation of the hypothalamic-pituitary-gonadal (HPG) axis. Most children (especially girls) suspected of having CPP do not have any specific abnormality but lie at one end of the normal distribution curve.
- Idiopathic (sporadic or familial).
- Abnormalities of the central nervous system (CNS) include:
- Tumours, including gliomas, astrocytomas, hamartomas, gliomas, pineal tumours and human chorionic gonadotrophin (hCG)-secreting germ cell tumours.
- CNS trauma or injury (causes include infection, radiation, surgery).
- Hamartomas of the hypothalamus.
- Congenital disorders such as hydrocephalus and arachnoid cysts.
- Where no such CNS abnormalities are found, the causes of an early, normal puberty include:
- Genetic. Often early puberty is familial and autosomal dominant in inheritance; Silver-Russell syndrome, McCune-Albright syndrome (MAS).
- Obesity: in girls, early puberty is associated with increased body mass index (BMI). This is particularly the case in white girls. Obesity is not associated with early puberty in boys.
Gonadotrophin-independent precocious puberty (or precocious pseudopuberty)
This accounts for about 20% of cases of precocious puberty. and some of the specific types are rare. The normal pattern of puberty is absent The gonad matures independently of GnRH stimulation and levels of testosterone and estradiol, LH and FSH are usually at pubertal levels (in the absence of gonadotrophin pulsatility). There is a flat GnRH response and no response to treatment with gonadotrophin-releasing hormone (GnRH) analogues. Causes include:
- Congenital adrenal hyperplasia (CAH).
- HCG-secreting tumours in the liver (hepatomas, hepatoblastomas), choriocarcinomas (of gonads, pineal gland, mediastinum, etc.) and adrenal tumours (rare).
- Ovarian tumours may cause either masculinisation or feminisation.
- MAS. Affected individuals are at risk of multiple endocrinopathies including thyrotoxicosis, Cushing's syndrome, acromegaly, hyperparathyroidism, etc.
- Testotoxicosis (or familial male precocious puberty) An autosomal dominant condition characterised by progressive pubertal changes, rapid physical growth, skeletal maturation and sexually aggressive behaviour in the first 2-3 years of life.
- Hypothyroidism or van Wyk-Grumbach syndrome. Growth is arrested (unusual with precocious puberty) rather than accelerated.
See separate article Puberty - Normal and Abnormal.
Early appearance of pubic hair (with or without axillary hair) but without other signs of puberty. Pubic hair may present in both boys and girls aged <7 years due to adrenal androgen secretion in middle childhood. Premature pubarche may be:
- Weak androgens from adrenal glands (premature adrenarche). Temporarily the pubic hair development is in advance of breast development and other changes. This is usually benign.
- Signs of severe androgen excess (including clitoral enlargement, growth spurt) may be due to:
- Congenital adrenal hyperplasia.
- Virilising tumours - for example, in the adrenal glands, the ovary or a dysgenetic testis.
- Cushing's syndrome.
- Exogenous androgens could also cause these changes (eg contact with topical androgen preparations).
- Androgen activity In a pubertal girl may be evidence of polycystic ovarian syndrome.
Breast development may occur in girls aged <3 years, and can then spontaneously regress. This is often seen in girls under the age of 3 years and is caused by maternal oestrogens in the early months. There is fairly static breast development before true puberty eventually occurs at the normal time. It is a benign condition confirmed by:
- Absence of any other signs of puberty.
- Normal growth with appropriate bone age (ie no growth spurt).
- Minimal increase in breast tissue with time (can even decrease).
- Appropriate uterine dimensions for age (ultrasound) with normal endometrial echo and no vaginal bleeding.
Investigations are used selectively after a thorough clinical assessment. Tests available to further refine the diagnosis are:
- Levels of sex steroid:
- Early morning testosterone in boys is higher in early puberty.
- Estradiol levels are a less reliable measure of stage of puberty in girls.
- Pubertal levels of sex steroid are found in gonadotrophin-independent precocious puberty.
- Gonadotrophins (luteinising hormone (LH) and follicle-stimulating hormone (FSH)):
- A random LH is a useful initial test for central precocious puberty (CPP). A random FSH will not distinguish prepuberty from puberty.
- Low or prepubertal levels with high sex steroid levels are found in gonadotrophin-independent precocious puberty.
- Adrenal steroid precursors if congenital adrenal hyperplasia (CAH) is suspected.
- HCG when hCG-secreting tumours are suspected.
- Urinary 17-ketosteroids to quantify the amount of adrenal androgens being produced.
- Diagnostic imaging:
- Pelvic ultrasound is essential in gonadotrophin-independent precocious puberty (precocious pseudopuberty) to detect ovarian tumours or cysts. Although not required in CPP, it will demonstrate changes in ovaries and uterus.
- Other ultrasound: testicular and adrenal ultrasound can help to establish diagnosis of tumours, but much better imaging is ultimately achieved with MRI for adrenal tumours.
- Hand and wrist X-rays for bone age:
- If bone age is within one year of chronological age, either puberty has not started or has only just started.
- If the bone age is two years advanced then puberty has probably been present for at least a year or is progressing rapidly.
- Bone scan is not routinely required but is useful with suspected McCune-Albright syndrome (MAS).
- Brain MRI to exclude CNS abnormalities associated with CPP. MRI should be performed in all males with sexual precocity and in patients with neurological signs or symptoms. MRI can be used selectively in girls.
- Pelvic MRI can be useful in girls to assess the uterus and ovaries.
- Other tests:
- Gonadotrophin-releasing hormone (GnRH) stimulation test (see also separate article Pituitary Function Tests): LH and FSH levels are measured sequentially after GnRH is given. The gonadotropin stimulation test is useful in the assessment of precocious puberty. There is a flat response in gonadotrophin-independent precocious puberty.
- Leuprolide acetate stimulation testing is an alternative and can accurately predict pubertal progression..
For cases of central precocious puberty (CPP) with no underlying brain pathology and no psychosocial complications, treatment for the pubertal changes alone may not be required. Puberty can be arrested and growth hormone given if the height prognosis is poor. Examples of treatment include:
- Surgery: tumours may require resection but resection rarely causes regression of the pubertal changes.
- Medical treatments include:
- Gonadotrophin-releasing hormone (GnRH) agonists are used in CPP, as well as for other aetiologies, including McCune-Albright syndrome (MAS) and testotoxicosis.
- Glucocorticoids are used for congenital adrenal hyperplasia (CAH).
- Testolactone is an aromatase inhibitor (therefore inhibits steroid biosynthesis). It is used most commonly for MAS but also in testotoxicosis.
- Tamoxifen may be used in MAS.
- Ketoconazole may be used (for example in testotoxicosis) to inhibit steroid biosynthesis.
- Cyproterone acetate may be used for anti-androgen action. Flutamide is also used to counter androgen excess.
- Medroxyprogesterone (a progesterone analogue) has also been used.
- Psychological difficulties, including feeling stressed and becoming withdrawn because of the early physical changes; bullying
- Behavioural problems and emotional problems
- Early puberty accelerates growth but bone maturation is also accelerated and so adult height is reduced.
Central precocious puberty (CPP)
- Without treatment most girls aged 6-8 years at the onset of their puberty will achieve adult height within the normal range.
- The prognosis otherwise depends on the underlying cause.
Gonadotrophin-independent precocious puberty
This depends on the aetiology. The possible diagnoses already discussed cover a range of possible outcomes. With early recognition and treatment the prognosis can be excellent.
Further reading & references
- Kaplowitz P, Precocious Puberty, Medscape, Mar 2010
- Cesario SK, Hughes LA; Precocious puberty: a comprehensive review of literature. J Obstet Gynecol Neonatal Nurs. 2007 May-Jun;36(3):263-74.
- Herman-Giddens ME, Kaplowitz PB, Wasserman R; Navigating the recent articles on girls' puberty in Pediatrics: what do we know and where do we go from here?; Pediatrics. 2004 Apr;113(4):911-7.
- Kaplowitz PB, Slora EJ, Wasserman RC, et al; Earlier onset of puberty in girls: relation to increased body mass index and race.; Pediatrics. 2001 Aug;108(2):347-53.
- Parent AS, Teilmann G, Juul A, et al; The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration.; Endocr Rev. 2003 Oct;24(5):668-93.
- Ng SM, Kumar Y, Cody D, et al; Cranial MRI scans are indicated in all girls with central precocious puberty.; Arch Dis Child. 2003 May;88(5):414-8; discussion 414-8.
- Kandemir N, Demirbilek H, Ozon ZA, et al; GnRH Stimulation Test in Precocious Puberty: Single Sample is Adequate for J Clin Res Pediatr Endocrinol. 2011 Mar;3(1):12-7. Epub 2011 Feb 23.
- Ng SM, Kumar Y, Cody D, et al; The gonadotrophins response to GnRH test is not a predictor of neurological lesion in girls with central precocious puberty.; J Pediatr Endocrinol Metab. 2005 Sep;18(9):849-52.
- Sathasivam A, Garibaldi L, Shapiro S, et al; Leuprolide stimulation testing for the evaluation of early female sexual Clin Endocrinol (Oxf). 2010 Sep;73(3):375-81. Epub 2010 Feb 23.
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Dr Richard Draper
Dr Colin Tidy