Growth and Puberty Flashcards
Overview of growth charts
-Weight, height and head circumference against the the normal distribution for their age and gender. The child’s measurements are plotted on a graph using a dot. The age is plotted on the x-axis and the weight, height and head circumference are plotted on the y-axis.
-Growth charts have curves that indicate the normal distribution of growth over time. Centiles (cent– meaning hundred) indicate where a child’s growth compares to the normal distribution for their age and sex. It is important to use the chart that matches the sex of the child, as growth is different between boys and girls.
Phases of growth
-First 2 years: rapid growth driven by nutritional factors
-From 2 years to puberty: steady slow growth
-During puberty: rapid growth spurt driven by sex hormones
Overview of childhood obesity
Obesity in children results from consuming more calories than are expended through activity and growth. Recently, access to readily available, affordable, hyper-palatable, high calorie foods has lead to the overconsumption of calories. There has been a shift from physical activities and outdoor play to sedentary activities such as video games and screens. This has contributed to an increase in childhood obesity.
Overweight is defined as a body mass index (BMI) above the 85th percentile and obese as above the 95th percentile. Obese children are often tall for their age and come from overweight families. If children are short and obese, consider endocrine investigations for an underlying cause, such as hypothyroidism. A pathological cause is rare.
The biggest immediate effect of obesity in children is bullying. Obese children at at higher risk of later developing impaired glucose tolerance, type 2 diabetes, cardiovascular disease, arthritis and certain types of cancer. Unless the family engages and addresses the issue it is likely to continue into adulthood and have all the associated negative health implications of adult obesity.
Male puberty
-First sign is testicular growth at around 12 years of age (range = 10-15 years)
-Testicular volume > 4 ml indicates onset of puberty
-Maximum height spurt at 14
Female puberty
-First sign is breast development at around 11.5 years of age (range = 9-13 years)
-Height spurt reaches its maximum early in puberty (at 12) , before menarche
-Menarche at 13 (11-15)
-There is an increase of only about 4% of height following menarche
Normal changes in puberty
-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.
-Gynaecomastia may develop in boys
-Asymmetrical breast growth may occur in girls
-Diffuse enlargement of the thyroid gland may be seen
Tanner scale can be used to determine pubertal stage based on exam findings of sex characteristics
Overview of precocious puberty
-Development of secondary sexual characteristics before 8 years in females and 9 years in males’
-More common in females, Males - uncommon and usually has an organic cause
-Thelarche (the first stage of breast development)
-Adrenarche (the first stage of pubic hair development)
May be classified into:
1. Gonadotrophin dependent (‘central’, ‘true’)
due to premature activation of the hypothalamic-pituitary-gonadal axis
=FSH & LH raised
2. Gonadotrophin independent (‘pseudo’, ‘false’), due to excess sex hormones
=FSH & LH low
-Testes
=Bilateral enlargement = gonadotrophin release from intracranial lesion
=Unilateral enlargement = gonadal tumour
=Small testes = adrenal cause (tumour or adrenal hyperplasia)
-Females - usually idiopathic or familial and follows normal sequence of puberty
-Organic causes are rare, associated with rapid onset, neurological symptoms and signs and dissonance e.g. McCune Albright syndrome
Causes of delayed puberty
-Hypogonadism
-Hypogonadotropic hypogonadism
-Hypergonadotropic hypogonadism
-Kallman Syndrome
Overview of hypogonadism
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
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
=Hypothyroidism
=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
Overview of Hypergonadotropic hypogonadism
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)
Overview of Kallman Syndrome
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).
Investigation of delayed puberty
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 of delayed puberty
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.
What is failure to thrive?
Failure to thrive refers to poor physical growth and development in a child. Faltering growth is defined in the 2017 NICE guidelines on faltering growth in children as a fall in weight across:
=One or more centile spaces if their birthweight was below the 9th centile
=Two or more centile spaces if their birthweight was between the 9th and 91st centile
=Three or more centile spaces if their birthweight was above the 91st centile
-Centile spaces are the distance between two centile lines on a growth chart. The distance between the 75th and 50th centile lines is a centile space. A weight that falls this distance is a drop across one centile space. For example, if the initial weight of a child is plotted halfway between the 9th and 25th centile lines and several months later is plotted halfway between the 2nd and 9th centile lines, they have dropped a full centile space.
Body mass index (BMI) can be used to assess growth in children over 2 years of age. We should suspect faltering growth if:
BMI is below the 2nd centile (can be due to undernutrition or a small build).
BMI is below the 0.4th centile (suggests probable malnutrition).
