Growth and Puberty Flashcards
What are the four phases of normal human growth?
Fetal, the infantile phase, childhood phase and the pubertal growth spurt
What is the size at birth determined by?
The size of the mother and by placental nutrient supply
What is growth during the infantile phase determined by?
Adequate nutrition, good health and normal thyroid function
What is failure to thrive?
Inadequate rate of weight gain during the infantile phase
What is growth during the childhood phase largely determined by?
Pituitary growth hormone secretion acting to produce IGF-1 at the epiphyses is the main determinant of a child’s rate of growth, provided there is adequate nutrition and good health.
What can negatively affect growth during the childhood phase?
Thyroid hormone, vitamin D and steroids. Profound chronic unhappiness can decrease GH secretion and accounts for psychosocial short stature
What causes the pubertal growth spurt?
Sex hormones, mainly testosterone and oestradiol, cause the back to lengthen and boost GH secretion
What stops growth?
Testosterone and oestradiol cause fusion of the epiphyseal growth places and a cessation of growth, so patients that suffer from early puberty may be short
How can growth be measured?
Weight, height/length (difficult in young children) and head circumference
What are the female features of puberty and when do they happen?
Breast development - 8.5-12.5 years
Pubic hair growth and growth spurt - immediately after breast development
Menarche - 2.5 years after the start of puberty
What are the male features of puberty and when do they happen?
Testicular enlargement - first sign of puberty
Pubic hair growth - between 10 and 14 years of age
Growth spurt - 18 months after testicular enlargement
What are features of puberty that are present in both sexes?
Acne, axillary hair, body odour and mood changes
How can abnormally early or late puberty by assessed?
Bone age measurement from X-ray
Females: pelvic US to assess uterine size and endometrial thickness
How is short stature defined
Height below the second centile or 0.4th centile
How do you measure height velocity and what is abnormal?
Two accurate measurements at least 6 months but preferably a year apart. A height velocity persistently below the 25th centile is abnormal and that child will be short.
How do you calculate a genetic target centile for growth?
The mean of the fathers and mothers height with 7cm added for the mid-parental target of a boy, and 7cm subtracted for a girl
What is the link between IUGR/extreme prematurity and growth?
1/3 of children born with severe IUGR or who were born extremely premature remain short. Growth hormone treatment may be indicated
What is constitutional delay of growth and puberty?
These children have delayed puberty, which is often familial, usually having occurred in the parent of the same sex
Is constitutional delay of growth and puberty more common in males or females?
Males
Which endocrine conditions can cause short stature?
Hypothyroidism, GH deficiency, IGF-1 deficiency and steroid excess are uncommon causes of short stature. They are associated with overweight children
Can you treat short stature due to hypothyroidism?
Yes, catch up growth rapidly occurs but often with a rapid entry into puberty that can limit final height
What is the main cause of hypothyroidism in children?
Autoimmune thyroiditis
Can you treat short stature due to corticosteroid therapy?
Normalisation of body shape and height occurs on withdrawal of treatment of the underlying steroid excess. Cushing syndrome during puberty can result in permanent loss of height
What may be short stature due to inadequate nutrition be due to?
Insufficient food, restricted diets or poor appetite associated with chronic illness, or from the increased nutritional requirement from a raised metabolic rate.
Which chronic diseases may present with short stature?
Coeliac disease
Crohn’s disease
Chronic renal failure
What chromosomal disorders can cause short stature?
Down syndrome (usually already diagnosed), but Turner (most common out of undiagnosed), Noonan and Russell-Silver syndromes may present with short stature
How would you treat short stature caused by growth hormone deficiency?
Subcutaneous injection of biosynthetic growth hormone
What are the causes of tall stature?
Familial, obesity, hyperthyroidism, excess sex steroids (precocious puberty), congenital adrenal hyperplasia, gigantism, Marfan syndrome, Klinefelter syndrome.
How does obesity affect growth?
Obesity in childhood ‘fuels’ early growth and may result in tall stature, however, because puberty is often somewhat earlier than average, so it does not always increase final height
When does the posterior and anterior fontanelle close?
Posterior - 8 weeks
Anterior - 12-18 months
What are the causes of microcephaly (small head)?
Familial
Autosomal recessive condition
Congenital infection
Acquired after an insult to the developing brain (hypoxia/meningitis/hypoglycaemia)
What are the causes of macrocephaly (big head)?
Tall stature Familial Raised ICP (make sure to exclude this) Hydrocephalus Chronic subdural haematoma Cerebral tumour Neurofibromatosis
What are the causes of an asymmetric head?
Imbalance of growth rate at the coronal, sagittal or lambdoid sutures, although the head circumference increases normally. Sometimes it’s just because the baby sleeps on it’s back and will improve on mobility
Should you investigate precocious puberty different in boys and girls?
In girls it is usually due to the premature onset of normal puberty.
In boys it more often has an organic cause (intracranial tumours)
How do you manage precocious puberty?
Treat cause, address psychological/behavioural difficulties associated with early puberty, if necessary GnRH analogues
What is premature breast development ?
Affects females between 6 months and 2 years old. Axillary and pubic hair and growth spurt is absent. It is non-progressive and self-limiting
When does premature pubarche occur (pubic hair development)?
Before 8 years old in girls and before 9 years old in boys
In what ethnicity is premature pubarche more common?
Asian and afro-Caribbean children
Does premature pubarche need treating?
No, it is usually self-limiting, but if an aggressive form it may be caused by an adrenal tumour so rule that out
What condition is at an increased risk after premature pubarche?
PCOS
Is delayed puberty more common in boys or girls?
Boys, mostly due to constitutional delay in growth and puberty.
What are the symptoms of delayed puberty?
Short during childhood, with a delay in sexual maturation and have delayed skeletal maturity on bone age. The legs will be long compared to the back. Target height will eventually be reached as they growth for longer
What disorders would you investigate in delayed puberty in boys and girls?
Boys - chronic systemic disorders
Girls - karyotyping to identify Turner’s syndrome, thyroid and sex steroid hormones.
How would you treat delayed puberty?
Treat underlying pathology. Reassure that puberty will occur, then treatment is not often needed. If it is, steroids or sex hormones can be given
What may be the cause of sexual differentiation (uncertainty about the infants sex)?
Excessive androgens producing virilisation in a female
Inadequate androgen action, producing undervirilisation in a male
Gonadotrophin insufficiency (Prader-Willi syndrome)
Ovotesticular disorder of sex development (both XX and XY containing cells present)
What can cause congenital adrenal hyperplasia?
A number of autosomal recessive disorders of adrenal steroid biosynthesis result in congenital adrenal hyperplasia, it is more common in consanguineous relationships
How may congenital adrenal hyperplasia present at birth?
Virilisation of the external genitalia in female infants, with clitoral hypertrophy and variable fusion of the labia.
In the infant male, the penis may be enlarged and the scrotum pigmented.
How may congenital adrenal hyperplasia present in the first few weeks after birth?
A salt-losing adrenal crisis may occur at 1-3 weeks of age, presenting with vomiting and weight loss, floppiness and circulatory collapse
What percentage of males are salt-losing in congenital adrenal hyperplasia
80% are salt-losing
20% are non-salt-losing
How may congenital adrenal hyperplasia present in later life?
Both male and female non-losers may present with tall stature, a muscular build, adult body odour, pubic hair and acne from excess androgen production, leading to precocious pubarche
How is congenital adrenal hyperplasia diagnosed?
Markedly raised levels of the metabolic precursor 17 alpha-hydroxyprogesterone in the blood.
In salt-losers: low plasma sodium, high plasma potassiu, metabolic acidosis, hypoglycaemia
How is congenital adrenal hyperplasia managed?
Affected females will sometimes require corrective surgery to their external genitalia within the first year, definitely before sexual intercourse is attempted. Lifelong glucocorticoids to suppress ACTH levels. Monitoring of growth, skeletal maturity and plasma androgens
How would you treat males in a salt-losing crisis?
Saline, dextrose and IV hydrocortisone
