Growth in childhood Flashcards
Factors which can adversely affect growth in height
nutrition, hormone problems, genetic diseases.
How long is the average term baby and how much do they weigh
50cm long and 3.3kg weight
What are centile charts commonly used for
height, weight, head circumference and BMI are the commonest
What must be done to ensure accurate height and weight are measured
The equipment should be accurate and maintained properly
Position the child properly to get an accurate height (read the instructions on the growth chart)
Make sure you get rid of things which interfere with measuring- shoes off, hair out of the way, clothes off to weigh.
Calculate the age and plot correctly on the chart.
Differentiate height velocity vs. what is shown on centile
The centile charts we use are for cumulative height – how tall the child is now, (the total of all the growth they have done up to now, from conception).
Height velocity is how fast a child is growing in cm per year, usually this is calculated over a whole year. Most short children are growing at a completely normal speed.
As well as centiles and height velocity, what else is useful information in assessing child growth
the height of family members- parents and siblings.
How do each of the following affect growth from conception into childhood
- Events before birth
- Think about
- Genetic factors
- Think about
- Events before birth- poor fetal growth, low birth weight, prematurity
- Medical issues in childhood- malnutrition, chronic disease, endocrine problems including growth hormone deficiency
- Genetic factors- the height of the family and any inherited disorders of growth.
- Randomness. Not every child of the same parents will be the same adult height, and tall parents can occasionally have a short child. There are multiple genes which determine adult height, and these are randomly distributed at conception.
What is the fastest phase of growth after birth (incl. puberty etc)
the first 2 years of life
When is there most fluctuation around a centile position for height during childhood, and when is does this normally fix
First 2 years of life. Children can move up and down through the centiles at this phase of growth.
Most children will move to a centile position by 2 to 3 years of age and then continue on this centile position through childhood.
T/f it is common for children to move around centiles throughout childhood. If you suspect a growth problem, how long would you need to monitor the child for
F Normal children grow fast enough to keep on the same centile and movement up or down is unusual.
Monitor for at least a year
When is there fast growth in childhood and what does this depend on
There is a phase of fast growth at puberty- the pubertal growth spurt. The timing of this depends on the age at which the child enters puberty.
When and why does growth stop
The skeleton matures as the child grows, the epiphyses fuse at the end of puberty, and growth stops.
T/f if a child is on the bottom of the centile chart they probably have a problem
F…. If a child is growing fast enough to continue to grow on the same centile they are not likely to have a problem even if they are at the bottom of the centile chart.
What can cause a child to fall behind in height during puberty
Timing of puberty can impact on height- children who are late in developing can fall behind in height.
Outline the key hormonal regulator of growth in children
i. where is it released from
ii. control of its release
iii. which factors mediate its release
Growth hormone (GH) is the most important hormonal factor in growth.
GH secretion is controlled by the hypothalamus, which secretes growth hormone releasing hormone (GHRH) which stimulates secretion and somatostatin which suppresses secretion.
Outline the pattern of GH release
H is released by the pituitary as pulses most of which occur overnight.
How does GH have its growth effects
GH has some growth effect itself and also stimulates the release of IGF1 (insulin like growth factor !).
How does IGF1 travel in the body
IGF 1 circulates bound to a number of binding proteins and stimulates growth in all the tissues of the body
Outline the negative feedback control of growth hormone release
IFG1 negatively feeds back to reduce GH release
And to increase somatostatin release from hypothalamus
Which factors influence the pulsatile secretion of the GH
Nutrition, health, age, puberty, psychological factors, exercise, sleep
Causes of abnormal growth
Poor nutrition, chronic disease, endocrine, genetic factors, psychoigcal distress and neglect
Examples of genetic and endocrine causes of short stautre
Endocrine causes- GH deficiency, thyroid hormone deficiency
Genetic disorders affecting bone growth (eg achondroplasia, Turner syndrome, Down syndrome, PWS).
Causes of tall stature
Sydromes- Marfan and Soto
GH pituitary tumour
Precocious puberty (pubertal growth spurt occurs very early and so children with this can present with tall stature. However growth stops early as well so they can then be short as adults.)
When is GH treatment beneficial and not beneficial
BENEFICIAL: Children with confirmed GH deficiency/other disorders of growth
NOT BENEFICIAL: children who do not have anything wrong with them but are just short (“short normal children”)… tiny imporvement not worth time, effort and expense
Define obesity in adults vs children
For adults BMI of over 25 kg/m2 is overweight and over 30 kg/m2 is obese.
Children have lower BMI than adults and this changes with age so these figures do not apply, and obesity is assessed on the BMI centile position.
T/f rate of obesity is increasing and will continue to go up at same rate
F Rates of obesity and overweight have increased but may not continue to go up at the same rate for the future
When is obesity seen as desirable feature
some cultures where overweight has traditionally been seen as a desirable feature indicating wealth and high status
T/F obesity is always associated with poverty
In some areas of the world obesity is a feature of poverty and in others associated with affluence.
Why can some ethnicities develop obesity related ompications at a lower BMI than others
Some ethnic groups have less “tolerance” of obesity and are more likely to get complications like type 2 diabetes at a lower BMI
What are the complications of obesity
Overweight and obesity makes you more likely to get a range of disorders including type 2 diabetes, cardiovascular disease, some cancers, orthopaedic problems, PCOS, psychological issues, respiratory difficulty .
Why does obesity happen
balance of energy taken in as food versus energy expenditure
What regulates hunger
regulated by the hypothalamus and there are a number of factors (including leptin) which regulate this.
Outline genetic basis for obesity
very small number of individuals with single gene mutations affecting one of these hormones which results in an excessive appetite and can lead to severe obesity (POMC and MCR4 deficiency, BUT NOT AGRP/NPY)
some gene variants which can affect eating behaviour and appetite and make an individual more likely to eat in a way that makes them gain weight.
Give an example of a gene variant that affects eating behavious and can make someong ain weight
FTO gene
When does the final part of growth occur, and which are the final epiphyses to fuse?
the bones mature and epiphyses fuse at the end of puberty.
The final part of growth occurs in the spine and the final epiphyses to fuse are in the pelvis.
Why do we measure growth
Poor growth in infancy is associated with high childhood morbidity and mortality.
Growth is best indicator of health
Demonstration of normality of growth by age and stage of puberty
Identify disorders of growth
Assess obesity
When measuring a baby height
Legs straight, feet flat against board
When is height velocity highest, and when else does it increase
Highest in first 2 years
Increases again at puberty (but nowhere near as much as first 2 years!)
Height velocity calculatuion
Units and how often to carry out
(Height now-height last visit)/(age now-age last visit)
cm/yr
interval 6 months
What type of molecule is GH
Single chain polypeptide
T/F GH and IGF-1 are both bound to plasma protein
T… there is a GH binding protein, and IGF1 binds to many binding proteins
When is THE most rapid phase of growth and what are the most important factors regulating this time
Antenatal
Maternal health and placenta
How much does child grow in first year, and what is this dependent on. What is growth dependent on after this time
23-25cm
For 1st year it is a continuation of foetal growth and is NUTRITIONALLY dependent.
After 9-12 months GH is now influential
What is childhood
Post infancy to adolescence
What stimulates the childhood growth and the pubertal growth spurt
Childhood- GH (less dependent on nutrition)
Puberty- GH + sex steroids
Are centiles a normal range
you can be taller or shorter than the centile lines and still be completely normal and healthy.
no, they are a population reference range
When is their definitely a problem in relation to height
A child who falls significantly in centile position is not growing normally, whatever their height.
T/F all children with IUGR catch up to
F
Growth will be normal in childhood but they have “lost” some height in the antenatal period.
T/f in syndromes causing abnormal growth (turners, down syndrome, skeletal dysplasia), there is abnormal hormone
What is the cause of the poor growth here
F… these are examples of abnormal growth but with normal hormones
Significant illnesses can interfere with growth, because of inflammation, poor nutrition and the effects of drugs such as steroids.
Test for if the child is growing at a steady rate but below the lowest centile
Birth history and weight
Parental heights
Medical history
Previous measurements
Steroid excess causes what kind of growth
Short stature (precocious puberty but can end up with growth stopping early)
What tests do you want to do if a child was feowing on a centile line then drops off
full blood count, CRP, serum iron Liver and kidney function thyroid function coeliac screen IGF 1 bone age
What test if the child is going above their centile
MRI pituitary and pit. function tests
What is the problem in achondraplasia
The sitting height is normal but the leg length is very short
Chronic paediatric disease
Asthma Sickle cell IBD: chrohn's/coeliac Juvenile chornic arthritis CF Renal failure Congenital heart disease
Syndromes associated with obesity
Prader willi
Cushings
