growth in childhood Flashcards
5 reasons to measure growth
poor infant growth associated with high childhood morbidity and mortality, growth best indicator for health, demonstrate normality of growth by age and stage of puberty, identify disorders of growth, assess obesity
how to measure length accurately for infant
measure length: legs straight, head and feet flat against board
how to measure height accurately for child
use stadiometer/tape measure when standing
what do centile growth charts express
variation within population; how many people in population are at a particular variable (e.g. height) at any age
examples of centile charts
head circumference, weight, height, leg length, BMI, growth velocity, specialist charts
describe 5th, 50th and 95th centiles
50th percentile is mean, 5-95th percentiles
why measure head circumference in adult
reflects brain development
guide to accurate plotting
plot with dot to determine if someone has dropped centiles
height velocity calculation
(height now - height last visit)/(age now - age last visit); expressed in cm/yr and interval approx. 6 months
what hormonal axis controls endocrine control of growth
GH-IGF-1 axis regulator of human linear growth (GH single chain peptide)
describe GH secretion from somatotroph cells of anterior pituitary
pulsatile, and influenced by nutrition, sleep, exercise and stress
describe hormonal control of growth axis
hypothalamus -> GHRH and somatostatin -> anterior pituitary -> GH (and GH binding protein) -> GH receptor -> GH action and IGF-1 production -> IGF-1 (liver; and IGF binding proteins) -> IGF-1 receptor -> IGF-1 action
phases of growth
antenatal (most rapid phase of growth) -> infancy -> childhood -> adolescence
what are important factors in antenatal phase of growth
maternal health, placenta
describe infant initial growth
rapid (23-25cm in first year) as continuation of foetal growth
what is infant growth dependent on
nutrition
after 9-12 months, what hormone influences infant growth
GH
describe childhood growth rates, and what drives it
growth rates similar in boys and girls, with GH/IGF-1 axis driving growth and nutrition having less impact
speed of growth in height velocity at puberty, and difference between males and females
females undergo puberty before males (peaks at 12 vs 14); puberty, sex steroids and GH stimulate pubertal growth spurt
what is bone age and how is it measured
bone maturity (membrane, cartilaginous or ossified), as X-rays only see ossified bone (gaps at growth plates seen to determine if maturing)
what happens to bones at end of puberty
mature and epiphyses fuse; final part of growth occurs in spine and final epiphyses to fuse are pelvis
4 main questions to ask about growth
is child too short/tall for age (could there be a problem), has puberty started/normal progression, is growth normal for stage of puberty, is child overweight/obese
4 main lessons from centile growth charts
centiles are not a “normal range” (can be taller/shorter and still normal and healthy), most children set out on a centile by 2 y/o and grow on same centile during childhood, pattern of growth is more important than position on centile, child who falls significantly in centile position is not growing normally (whatever their height)
7 causes of short stature
genetic, pubertal and growth delay, IUGR/SGA, dysmorphic syndromes, endocrine disorders, chronic paediatric disease (inflammation attached to cells block IGF pathway), psychosocial depravation
causes of short stature with normal growth pattern, and consequence of IUGR
most short children have short parents and no medical issues; not all children with IUGR catch up completely, as growth is normal in childhood but would have “lost” some height in antenatal period
4 criteria to think about with small child on growth chart
birth history and weight, parental heights, medical history, previous measurements
mid parental centile equation
male (combined parents height/2)+7cms; female (combined parents height/2)-7cms
3 endocrine problems causing abnormal growth pattern, short stature and reduced growth velocity
hypothyroidism, GH deficiency, steroid excess
4 criteria to think about with small child on growth chart who isn’t growing parallel to centiles
full blood count, CRP, serum iron, kidney and liver function, thyroid function, coeliac screen, IGF-1, bone age
2 investigations for endocrine cause of short stature
MRI pituitary, pituitary function testing
3 syndromes causing abnormal growth despite normal hormones
Turner syndrome (XO), Down syndrome (T21), skeletal dysplasias
why can significant illnesses interfere with growth
inflammation, poor nutrition and the effects of drugs such as steroids
describe Turner syndrome (XO) and treatment
normal intelligence, short; normally don’t go into puberty so induce puberty and give GH
describe achondroplasia
measure full and sitting height to give leg length (very short)
7 chronic paediatric diseases
asthma, sickle cell, juvenile chronic arthritis (pro-inflammatory cytokines), inflammatory bowel disease (Crohns, coeliac), CF, renal failure, congenital heart disease
4 causes of tall stature
tall parents, early puberty, syndromes e.g. Marfans, GH excess (gigantism)
3 problems of global obesity
widespread, high prevalence and costly consequences
why is obesity harmful
emotional and behavioural, school absence, high cholesterol, high blood pressure, pre-diabetes, bone and joint problems, breathing difficulties, increased risk of becoming overweight adutls, risk of ill-health and premature mortality in adult life
7 complications of obesity and associated features
T2DM, orthopaedic problems, PCOS, CVD, psychological problems, cancer, respiratory difficulties
BMI in children vs adult
varies
prevalence of excess weight among children
1/5 in reception, 1/3 in year 6
obesity prevalence by deprivation decile
least deproved centiles is least obesity, most deprived centiles is most obesity
6 features of childhood obesity
decreased exercise, increased calorie consumption, association with increased TV watching, consumption of soft drinks, parental obesity, education and social factors
3 syndromes associated with obesity (tend to be short also)
Cushing’s, Prader-Willi (parental disomy), Lawrence-Moon-Biedl
genetics of weight: inheritance and heritability
high heritable trait with majority being polygenic (some rare monogenic obesity syndromes)
5 examples of rare monogenic obesity syndromes
leptin deficiency, leptin receptor deficiency, POMC deficiency, PC-1 deficiency, MC4R deficiency
