Paeds: Endocrinology (1) Flashcards
What’s auxology?
Auxology → study of human growth using repeated measurements in the same individual over successive time periods
Define short and tall stature
Short stature → height less than 2SD below mean for age and sex
Tall stature → height more than 2SD above mean for age and sex
What factors growth is dependant on across a child’s lifespan?
- foetal
- infantile
Foetal: genotype, maternal factors, in utero environment and foetal and maternal hormones (IGF2,IGF1,Placental GH, Thyroid hormone etc.)
Infantile: mainly first 2 years, rapid but decelerating. Mainly nutrition dependent
What factors growth is dependant on across a child’s lifespan?
- childhood
- puberty
Childhood: 3 years to puberty. Mainly Growth Hormone (GH) and T4 driven
Puberty : Variable onset, different pattern in girls and boys , hypothalamic-pituitary-gonadal axis (HPG) axis activation and GH secretion
Factors affecting growth
- Birth weight
- Nurture
- Family heights
- Thyroid hormone
- Growth hormone
- Pubertal hormones
- Various growth factors
- Nutrition
- Illnesses and medication
- Onset of puberty
Types of growth
There are three types of growth;
- Infancy (birth to 2-years-old)
- Childhood (3 to 11-years-old)
- Puberty (12 to 18-years-old)
Infantile growth
- how much?/rate
- factors influencing growth
Infantile growth (birth - 2 years)
25 cm/year
Principle influences on growth:-
- birth size
- psychosocial stimulation
- nutrition
*Hormones are relatively unimportant for growth at this age
*Any chronic disease can impact on growth
Childhood growth
- how much/rate
- factors influencing it
Childhood growth
(3 - 11 years old)
4-8 cm / year
- Growth hormone essential for normal growth
- Psychosocial environment remains very important
- Effect of childhood obesity on growth is observed
- Chronic disease remains important cause of growth failure
Pubertal growth phase
- when
- what happens
Pubertal growth phase
(12-18 years old)
- Production of sex hormones
- Increased production of growth hormone
- Rapid growth
- Chronic diseases impact on both growth and pubertal development
What happens first-last in terms of secondary sexual characteristic development in boys?
testicular growth → penis, pubic and axillary hair → acceleration in height velocity → voice deepens, facial hair
What happens first-last in terms of secondary sexual characteristic development in girls?
breast growth → acceleration in height velocity → pubic and axillary hair growth → menarche
aetiology of ‘short stature’
- familial
- Cconstitutional
- Small for gestational age with poor catch up growth
- syndromes
- skeletal dysplasia
- chronic disease
- endocrine causes (GH, thyroid, cortisol)
- psychological
- idiopathic
Hx in short stature
- Growth pattern
- General health
- Pregnancy and birth
- Medical history
- Family history
- Social and educational
Elements of clinical examination in short stature
- Facial features
- Disproportion, asymmetry
- Eyes
- Skin and limbs
- Systemic examination
- Pubertal assessment
Investigations in short stature
- Renal, bone, liver
- FBC, ESR
- TTG (tissue transglutaminase)
- Karyotype
- TFT, IGF1, Prolactin, cortisol
- Bone age
- Dynamic tests
- Skeletal survey
- MRI
Growth Hormone
- what’s that
- what is it secreted by
- function
- secretion patterns
- hormones influencing secretion of GH
- Protein hormone synthesised and secreted by anterior pituitary (somatotrophs)
- Major role in growth and acts via IGF1
- Secreted in pulses during deep sleep
- Secretion controlled by Growth Hormone Releasing Hormone (GHRH), Somatostatin, Ghrelin
What conditions growth hormone therapy is recommended for?
- GH deficiency
- Turner syndrome
- Prader-Willi syndrome
- Chronic renal insufficiency
- Small for gestational age babies with poor catch up growth
- SHOX deletion
Growth Hormone therapy
- administration route
- when to discontinue treatment
- given by subcutaneous injection (SC)
- treatment should be discontinued if there is a poor response in the first year of therapy
SEs of growth hormone therapy
- headache
- benign intracranial hypertension
- fluid retention
Features of Turner’s syndrome
- short stature
- shield chest, widely spaced nipples
- webbed neck
- bicuspid aortic valve (15%), coarctation of the aorta (5-10%)
- primary amenorrhoea
- cystic hygroma (often diagnosed prenatally)
- high-arched palate
- short fourth metacarpal
- multiple pigmented naevi
- lymphoedema in neonates (especially feet)
- gonadotrophin levels will be elevated
- hypothyroidism is much more common in Turner’s
- horseshoe kidney: the most common renal abnormality in Turner’s syndrome
Genetic pathology in Turner’s syndrome
- caused by either the presence of only one sex chromosome (X) or a deletion of the short arm of one of the X chromosomes
- denoted as 45,XO or 45,X
Definition of precocious puberty
- ‘development of secondary sexual characteristics before 8 years in females and 9 years in males’
*more common in females
What’s thelarche?
Thelarche → the first stage of breast development
What’s adrenarche?
Adrenarche → the first stage of pubic hair development
Classification of precocious puberty (2) due to causes
- Gonadotrophin dependent (‘central’, ‘true’)
- due to premature activation of the hypothalamic-pituitary-gonadal axis
- FSH & LH raised
- Gonadotrophin independent (‘pseudo’, ‘false’)
- due to excess sex hormones
- FSH & LH low
Characteristics of gonadotropin dependent precocious puberty?
Gonadotrophin dependent (‘central’, ‘true’)
- due to premature activation of the hypothalamic-pituitary-gonadal axis
- FSH & LH raised
Characteristics of gonadotropin independent precocious puberty
Gonadotrophin independent (‘pseudo’, ‘false’)
- due to excess sex hormones
- FSH & LH low
Potential causes of enlargement of testes
- bilateral
- unilateral
- small testes
- bilateral enlargement = gonadotrophin release from intracranial lesion
- unilateral enlargement = gonadal tumour
- small testes = adrenal cause (tumour or adrenal hyperplasia)
The usual cause of precocious puberty in:
- male
- female
Male → organic
Female → idiopathic, familial
Causes of gonadotropin dependent precocious puberty in males
Causes of gonadotrophin dependent precocious puberty in males
- CNS lesions: craniopharyngioma, hydrocephalus, neurofibroma, tuberous sclerosis
- hCG secretion hepatoblastoma
- primary hypothyroidism (increased TSH stimulates FSH receptors)
