Post natal growth Flashcards
What are the three phases of growth?
Infant - rapid growth at birth, declining rapidly over the first 2 years
Childhood - constant annual growth (GH dependent)
Puberty - rapid growth primarily dependent on sex steroids and increased GH release
What is the equation to estimate height of a child?
Called mid-parental height
For boys:
Dad height + (Mums height +13)/2
For girls
(Dad - 13 cm) + mum/2
Mid-parental height is +/- 8 cm
What is height velocity?
The growth between two time points divided by the time.
Work out that growth om a year
What are the causes of short stature?
What would you examine?
Poor measurement.
Genetic disorders, endocrine disorders, cartilage or bone disorders, general chronic disease
Normal variance (should have normal height velocity): Familial short stature, Constitutional delay in growth and development Pathological short stature (proportionate or disproportionate)
Poor height velocity: Symptom of a disease interrupting growth Usually pathology. Is the body proportionate? Did they loose their teeth at the expected time. Many systemic illnesses Hormone deficiency - GH, thyroid Dysproportionate - skeletal dysplasia Small for gestational age.
Mid-parental height: find the expected heights from parental height.
Family history of delayed puberty (when did mother have first period)
Look at other siblings development
Symptoms of underlying disease.
What is bone age?
Tells you the skeletal maturity, which tells you the age of the body and how tall they are likely to get.
How do you differ people with familial short stature and those with constitutional growth delay?
Those with constitutional growth delay have slow (but normal) height velocity in late childhood and a delayed bone age.
Puberty will be delayed but their final height will be normal.
Those with familial short stature will have normal height velocities, normal bone age, will enter puberty at a normal time but will be short.
How is growth hormone secreted?
Pulsatile with low baseline, primarily at night
Increased by sleep, exercise, stress, hypoglycaemia, amino acids, malnutrition, sex steroids.
Decreased by obesity, psychological deprivation
How is GH produced?
Hypothalamus produces growth hormone releasing hormone that acts on the anterior pituitary. This causes the release of GH.
GH acts on the liver to produce IGF-I.
GH breaks down fat -> FFA.
IGF-I and FFA negative feed back on the pituitary and hypothalamus.
IGF-I can be measured in the blood.
malnutrition can reduce the production of IGF-1 by the liver.
What are the functions of GH?
Inhibits glucose uptake and promotes glycogenolysis (anti-insulin)
Stimulates protein synthesis
Stimulates bone development
Promotes lipolysis
It functions in the growth plate by binding to a receptor on cells causing the prodction of IGF-I, which has an autocrine and paracrine function. This causes the cells differentiate and proliferate. Estrogen determines when it closes.
What is Laron Dwarf syndrome?
GH receptor defect
Short
What is the function of IGF-I (somatostatin)
Major post natal growth factor. acts on a widerange of tissues.
Produced in the liver (endocrine) and bone (paracrine/autocrine).
Insuling-like (promoting glucose, amino acid and lipid uptake).
Causes cell proliferation and cell differentiation.
What is the role of estrogen in growth?
It has an effect on skeleton and body composition. Important for bone density. Redistribution of body fat (breast and hips fir girls).
Causes epiphyseal maturation/closure in both sexes.
Lack of estrogen makes the growth phase continue for an extended duration because the growth plates wont close. No puberty, no growth spurt but continued growth.
What proteins are important at different stages of development?
Foetus: IGF-II, insulin
Child: GH, IGF-I, T4/T3
Puberty: GH, IGF-I, estrogen/testosterone, insulin, T4/T3
Insulin: facilitatory role in growth, provides substrates for growth (amino acid uptake, glycogenesis and lipogenesis)
Thyroid hormone - facilitatory role in growth, necessary for normal GH secretion, necessary for growth plate development and body proportions.
What are some pathological short stature conditions?
Proportionate:
Intrauterine growth retardation or small for gestational age (<10th PC for gestational age, usually catch up growth above 3rd PC by 6 months, if not can be short final height)
Syndromes: such as turner syndrome
Psychosocial deprivation
Disproportionate:
Syndromes (Turners)
Hypothyroidism
Skeletal dysplasias
What is Turner’s syndrome?
45 XO
Normal thyroid function tests
Elevated LH and FSH (primary gonadal failure)
Less estrogen and progesterone - not puberty growth spurt
Should be considered in all girls with unexplained short stature below the maternal-paternal height.
All short stature (50% this will be the only feature)
Poor height velocity or delayed puberty.
May have beck webbing, hand and foot oedema as an infant, wide spaced nipples, increased carrying angle, cardiac abnormalities, renal/urinary tract abnormalities.
