Puberty starts age 8 – 14 in girls and 9 – 15 in boys. It takes about 4 years from start to finish. Girls have their pubertal growth spurt earlier in puberty than boys.
In girls, puberty starts with the development of breast buds, then pubic hair and finally starting menstrual periods about 2 years from the start of puberty.
In boys, puberty starts with enlargement of the testicles, then of the penis, gradual darkening of the scrotum, development of pubic hair and deepening of the voice.
The tanner scale can be used to determine the pubertal stage based on examination findings of sex characteristics.
Hypogonadism refers to a lack of the sex hormones, oestrogen and testosterone, that normally rise prior to and during puberty. A lack of these hormones causes a delay in puberty. This is fundamentally due to one of two reasons:
- Hypogonadotrophic hypogonadism: a deficiency of LH and FSH
- Hypergonadotrophic hypogonadism: a lack of response to LH and FSH by the gonads (the testes and ovaries)
Hypogonadotropic hypogonadism is where there is a deficiency of LH and FSH, leading to a deficiency of the sex hormones testosterone and oestrogen. LH and FSH are gonadotrophins. Since there are no gonadotrophins simulating the gonads, they do not respond by producing sex hormones (testosterone and oestrogen). Therefore, you get “hypogonadism” as a result of “hypogonadotropism”.
A deficiency of LH and FSH is the result of abnormal functioning of the hypothalamus or pituitary gland. This could be due to:
- Previous damage to the hypothalamus or pituitary, for example by radiotherapy or surgery for previous cancer
- Growth hormone deficiency
- Hyperprolactinaemia (high prolactin)
- Serious chronic conditions can temporarily delay puberty (e.g. cystic fibrosis or inflammatory bowel disease)
- Excessive exercise or dieting can delay the onset of menstruation in girls
- Constitutional delay in growth and development is a temporary delay in growth and puberty without underlying physical pathology
- Kallman syndrome
Hypergonadotropic hypogonadism is where the gonads fail to respond to stimulation from the gonadotrophins (LH and FSH). There is no negative feedback from the sex hormones (testosterone and oestrogen), therefore the anterior pituitary produces increasing amounts of LH and FSH to try harder to stimulate the gonads. Therefore, you get high gonadotrophins (“hypergonadotrophic”) and low sex hormones (“hypogonadism”).
Hypergonadotrophic hypogonadism is the result of abnormal functioning of the gonads. This could be due to:
- Previous 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)
Kallman syndrome is a genetic condition causing hypogonadotrophic hypogonadism, resulting in failure to start puberty. It is associated with a reduced or absent sense of smell (anosmia).
The threshold for initiating investigations is when there is no evidence of pubertal changes in a girl aged 13 or a boy aged 14. The first step is to take a detailed history of their general health, development, family history, diet and lifestyle. An examination to assess height, weight, stage of pubertal development and features of underlying conditions. Investigation can also be considered when there is some evidence of puberty but no progression over 2 years.
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:
- Early morning serum FSH and LH (the gonadotropins). These will be low in hypogonadotrophic hypogonadism and high in hypergonadotrophic hypogonadism.
- Thyroid function tests
- Growth hormone testing. Insulin-like growth factor I is often used as a screening test for GH deficiency.
- Serum prolactin
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:
- Xray of the wrist to assess bone age and inform a diagnosis of constitutional delay
- 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 involves treating the underling condition where there is one. Patients with constitutional delay may only require reassurance and observation. Replacement sex hormones (oestrogen in girls and testosterone in boys) can be used to induce puberty under expert guidance.
Last updated January 2020