Normal Puberty
Puberty typically starts at age:
- 8 – 14 in girls
- 9 – 15 in boys
Puberty typically takes about 4 years from start to finish. Girls have their pubertal growth spurt earlier in puberty than boys.
In girls, changes occur in roughly the following order:
- Development of breast buds
- Development of pubic hair
- Onset of menstrual periods (about 2 years after the start of puberty)
In boys, changes occur in roughly the following order:
- Enlargement of the testicles
- Enlargement of the penis
- Gradual darkening of the scrotum
- Development of pubic hair
- Deepening of the voice
The Tanner scale can be used to determine the pubertal stage based on examination findings of sex characteristics.
Hypogonadism
Hypogonadism refers to a lack of the sex hormones, oestrogen and testosterone, that rise during puberty. These hormones are controlled by the gonadotropins, follicle-stimulating hormone (FSH) and luteinising hormone (LH), released by the anterior pituitary gland.
A lack of oestrogen or testosterone results in delayed puberty. This occurs due to either:
- Hypogonadotropic hypogonadism: a deficiency of LH and FSH
- Hypergonadotropic hypogonadism: a lack of response to LH and FSH by the gonads (the testes and ovaries)
Hypogonadotropic Hypogonadism
Hypogonadotropic hypogonadism is where there is a deficiency of LH and FSH (the gonadotropins), leading to a deficiency of the sex hormones testosterone and oestrogen (hypogonadism).
Reduced LH and FSH results from abnormal functioning of the hypothalamus or pituitary gland. Causes include:
- Damage to the hypothalamus or pituitary (e.g., radiotherapy or surgery for previous cancer)
- Growth hormone deficiency
- Hypothyroidism
- Hyperprolactinaemia (raised prolactin)
- Chronic diseases (e.g., cystic fibrosis or inflammatory bowel disease)
- Excessive exercise or dieting
- Constitutional delay in growth and development (temporary delay without underlying pathology)
- Kallmann syndrome (a genetic condition with delayed puberty and reduced sense of smell)
Hypergonadotropic Hypogonadism
Hypergonadotropic hypogonadism is where the gonads (ovaries or testes) fail to respond to stimulation from the gonadotrophins (LH and FSH), resulting in reduced oestrogen or testosterone production (hypogonadism). There is reduced negative feedback on the pituitary from the sex hormones, resulting in increased LH and FSH release (hypergonadotropic).
Hypergonadotropic hypogonadism results from abnormal functioning of the gonads. This could be due to:
- Damage to the gonads (e.g., testicular torsion, cancer or infections, such as mumps)
- Congenital absence of the testes or ovaries
- Kleinfelter’s Syndrome (XXY)
- Turner’s Syndrome (XO)
Investigations
The threshold for investigations is:
- No pubertal changes in a girl by age 13
- No menstrual periods by age 15 (or 3 years after the start of breast development)
- No pubertal changes in a boy by age 14
- Early pubertal changes, but no progression over two years
The first step is to take a detailed history of their general health, development, family history, diet and lifestyle. Examination is required to assess height, weight, pubertal development stage, and any underlying condition.
Initial investigations can be used to look for underlying medical conditions:
- Full blood count and ferritin for anaemia
- U&E for chronic kidney disease
- Anti-TTG or anti-EMA antibodies for coeliac disease
Hormonal blood tests can be used to look for hormonal abnormalities:
- Oestradiol (girls) or testosterone (boys)
- FSH and LH (early morning sample)
- Thyroid function tests (for hypothyroidism)
- Insulin-like growth factor I (for GH deficiency)
- Prolactin (for hyperprolactinaemia)
Genetic testing with a microarray test can be used to look for underlying genetic conditions:
- Kleinfelter’s syndrome (XXY)
- Turner’s syndrome (XO)
Imaging can be useful:
- X-ray of the wrist to assess bone age and inform a diagnosis of constitutional delay in growth and development
- Pelvic ultrasound in girls to assess the ovaries and other pelvic organs
- MRI of the brain to look for pituitary pathology and assess the olfactory bulbs in possible Kallman syndrome
Management
Management involves treating the underlying condition, if there is one. Patients with constitutional delay may only require reassurance and observation. Replacement sex hormones (oestrogen in girls and testosterone in boys) may be considered to induce puberty under expert guidance.
Last updated November 2025
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