Growth Flashcards
How is prematurity adjusted for in a growth chart?
Prematurity= <37 weeks gestation
Actual age is plotted on the graph and then arrow is drawn to adjust to gestational age: go back the number of weeks they were born premature.
What is defined as a failure to thrive?
Growth that crosses two centiles on a growth chart - needs prompt assessment and investigation.
What is the definition of growth failure?
Where height is below the 25th centile for a period of at least 18 months.
How do you calculate the mid -parental height
(Father’s height (cm) - Mother’s height (cm) ) / 2 +7cm for boys, or - 7cm for girls
How is BMI calculated?
Weight (kg)/ Height (m)^2
What is are the upper and lower limits of normal birth weight?
Low birth weight = <2500g
High birth weight = >4000g
Why is some allowance for low weight allowed in the first 2 weeks?
Babies may lose up to 10% of the body weight within the first two weeks
What are the four phases of normal growth?
- Foetal growth:
Fastest period of growth - determined by mother size and placental nutritional supply
Hormones involved = IGF-2, insulin, HPL
2.Infancy phase:
Rapid deceleration of growth in the first 2-3 years of life.
Fastest period of growth apart from foetal - peak of 18cm per year .
3.Childhood phase:
Slowest phase - from 2/3 years to puberty.
Initially determined by nutrition, then later by hormones e.g. GH
4.Pubertal phase:
Growth spurt occurs from puberty to 14/15 in girls, and 16/17 in boys.
Determined by GH and sex hormones - peak is at around Tanner stage 3.
What marks the end of the pubertal growth spurt?
Fusion of the epiphyses due to action of oestrogen.
What are the Tanner Stages of development?
Male - testicular volume:
Tanner 1 = <1.5ml - small penis
Tanner 2 = 1.6-6ml - scrotum skin thins, penis length unchanged
Tanner 3 = 6-12ml - penis begins to lengthen
Tanner 4 = 12-20ml - scrotum enlarges and penis continues to lengthen
Tanner 5 = >20ml - adult scrotum and penis by 14/15 y/o
Female - breasts:
Mnemonic = No-Body Elevates 2 mountains in Adulthood
Tanner 1 = NO glandular tissue
Tanner 2 = Breast bud forms, with some glandular tissue and areola widening
Tanner 3 = Breast elevated and extends beyond borders of areola
Tanner 4 = Areola and papilla form secondary mound - increasing in size and elevation
Tanner 5 = Adult size breasts -
Both - pubic hair:
Mnemonic = she/he’s Not a Small CAT
Tanner 1 = No hair
Tanner 2 = Small amount of downy hair, with slight pigmentation
Tanner 3 = Coarse and wiry hair - extending laterally
Tanner 4 = Adult-like but thigh sparing
Tanner 5 = Thighs not spared
Explain the growth hormone axis…
- GH- releasing hormone (GHRH) and Somatotropin release inhibiting factor (SRIF / somatostatin) are released by hypothalamus.
- GHRH stimulates GH release from somatotrophs, and somatostatin inhibits release.
- GH has direct effecton promotion of bone growth AND stimulates production of IGF-1 in the liver - which is released as free IGF-1.
- IGF-1 is transported to bone where it stimulates proliferation of epiphyseal growth plate.
- IGF-1 has negative feedback on pituitary and hypothalamus.
GH has negative feedback on hypothalamus.
What is the definition of short stature?
Height that is >2 SDs from the mean (below second centile)
What are some causes of short stature?
Commonest: familial short stature or constitutional delay
Primary growth disorders:
- Genetic syndromes= Down’s, Turner’s
- IUGR
- Congenital bone disorders = osteogenesis imperfeta
Secondary growth disorders:
- Psychosocial deprivation
- Malnutrition
- Chronic disease
- Endocrine disorders e.g. GH deficiency
- Medication e.g. steroids
If the child is small, but following the centile lines - what should be considered?
- Familial short stature
- Low birthweight
- Constitutional delay
Important features of history in short stature…
- Obstetric history - any prenatal complications, prematurity
- Feeding history
- Family history of growth disorders
- Developmental milestones
- Systems review to identify any underlying chronic disease
If no signs of disease in child with short stature, what should be done?
Review growth in 12 months - then calculate growth velocity.
What investigations can be carried out for short stature?
Bloods:
- FBC: anaemia in chronic disease e.g. IBD
- U&Es: renal disorders
- Bone profile: bone disorders
- TSH: hypothyrodism
- CRP/ ESR: IBD
- EMA/ TTG: coeliac disease
- IGF-1 measurement
- Dexamethasone suppression test: Cushing’s (steroid excess)
- Genetic karyotype: chromosomal disorders
Imaging:
- X-ray of hand and wrist: identify bone age - delay in GH deficiency but no delay in familial short stature
- MRI head: rule out intracranial tumours if neuro signs
- Skeletal survey: Scoliosis present
How do familial short stature and constitutional delay differ on growth charts?
- Familial short stature will have consistent low level throughout growth chart
- Constitutional delay will have low growth initially, followed by crossing centiles at puberty to a final normal adult height
What are the causes of GH deficiency?
- Isolated defect
- Secondary to panhypopituitarism - craniopharyngioma, head trauma , meningitis
How is GH deficiency treated?
Subcutaenous GH injections at night- improves muscular strength, body composition and vertical height.
What are the causes of failure to thrive?
Non-organic: environmental and social deprivation e.g. lack of food available
Organic:
- Inadequate intake due to impaired suck/swallow reflex
- Inadequate retention due to vomiting/ GORD
- Increased nutritional requirements due to chronic illness
- Failure to utilise nutrients
- Impaired nutrient absorption e.g. coeliac
