The fundamental mechanisms of puberty and human growth Flashcards
what are the requirements for normal human growth
Absence of chronic disease
Emotional stability, secure family environment
Adequate nutrition
Normal hormone/growth factor actions
Healthy growth plates
what are the 3 phases of growth
infancy
childhood
puberty
how do you work out overall growth
- infancy + childhood + puberty
what causes growth in …. and how much do they grow each year
infancy
- nutrition
- 25cm year
childhood
- GH IGF
- 4-8cm a year
puberty
- sex steroids + increase in GH
- peak is 8-12cm/year
why do we measure height and weight
- it is useful as an indicator of general health and well being in children
what is illness do height and weight measurements pick up
Short stature disorders: Growth hormone deficiency and Turner syndrome
More controversial: Screening for tall stature
what are the elements of a well functioning monitoring
Calibrated equipment
Correct measurement technique
Systematically collected growth data
Appropriate, up-to-date growth reference
Screening rules for abnormal growth
Referral criteria
Adherence to guidelines
Appropriate diagnostic work-up
how do you measure weight in babies
- they should not be weighted without any clothes or nappy
how do you measure height in children
- class III clinical electronic scales
- they can be weighed in vest and pants but no shoes, footwear and dolls or teddies in hand
how do you measure length
Measure length before age 2 years if concerned
Use proper equipment (length board or mat)
Requires two measures
No nappy of footwear
how do you measure height
From 2 years of age using a rigid ruler, or stadiometer
Ensure heels, bottom, back and head are touching the apparatus
Don’t try to stretch up, measure on expiration
No footwear
what do the centiles show
- they show the optimum range of weights and heights
if you are in the 50th percentile what does that mean
it means that 50% of other kids are below that measurement
what centiles are half of all children between
Half of all children between 25-75 centile
where are preterm babies plotted
- they are plotted on the preterm section
where are term birth measurements made
they are made at 0
why is there no 1 week
- because babies loose weight after they are born this is due to the water that they loose
if the point is within 1/4..
If the point is within 1/4 of a space of the centile line, the child is described as being “on the xth centile (see A) e.g. on the 91st centile.
if the point is not between 1/4 ..
If not they should be described as being “between centile X and Y (see B) e.g. between the 75th and 91st centile
when do individual children need further assessment of growth
- Where weight or height or BMI is below the 0.4th centile, unless already fully investigated at an earlier age.
- If the height centile is more than 3 centile spaces below the mid-parental centile.
- A drop in height centile position of more than 2 centile spaces, as long as measurement error has been excluded.
what is the diagnosis causing advance bone age
- tall stature
- central precocious puberty - child at the age of 9.5 has an advanced age of puberty
wha tis the diagnosis of delayed bone age
- growth failure secondary to paediatric
- Cushings disease- excessive production of cortisol that halts growth
what is short stature
Short stature is defined as a length or height
less than −2 SDS = 2.3 centile for age and sex of the appropriate reference population
how do you evaluate short stature
- Height centile vs. weight centile
- Failure to thrive or failure to grow - When started
- In utero
- In infancy
- In childhood
- In puberty - Body proportions
- Primary or secondary growth disorder - Presenting signs
- ISS or a specific diagnosis
how do you test proportionate growth failure
- psychosocial assessment - psychosocial growth retardation
- syndromic features karyotype - Turner syndrome
- tests for systemic disorders - chronic renal insufficiency, GI Disease nutritional deficiency
- tests for endocrine disorders - hypothyroidism, hypercortisolism
how do you assess linear growth
- Detailed auxological assessment - Length, height, sitting ht, head circumference (<2 yr). Compare against appropriate national
growth standards - Consider genetic growth potential from parental heigh
- Estimate height velocity over an appropriate period of time
- Bone age assessment
- Signs and symptoms of underlying cause
- Assess pubertal status
describe how maturation of the HPG axis works
- There are phases that of through mini puberty – this is where there is a normal physiologial activity and then it goes back down
what is puberty
Puberty is the normal developmental stage when reproductive capacity is attained
what is activated in puberty
GnRH secretion and the HPG axis are re-activated
Initiated by pulsatile GnRH release from hypothalamus
what is the name that we use to stage puberty
Tanner
what is puberty onset defined as for girls
Tanner stage B2 for girls (budding of the breast)
what is puberty onset defined as for boys
Tanner Stage G2 = Testis volume > 3mL in boys
what is the mean age onset for girls and boys
Mean age onset 11yrs for girls and 12yrs for boys
where does peak heigh velocity happen in girls and in boys
- early stage in girls
- mid stages in boys
what is the range of onset for girls and boys for puberty
In girls between 8-13 years
In boys between 9.5-14 years
describe boys and height
- they have a 2 additional years of prepubertal growth
- and a taller prepubertal height in males
- this leads to a 13cm difference in adult height
what is mid puberty for boys
10 ml testes
what is mid puberty for girls
menarche
what are factors that influence the timing of puberty
- genetic factors
- intrauterine growth
- childhood growth
- fat mass - leptin
- nutrition
- adoption
- migration
- endocrine disrupting chemicals
what does early puberty leda to
Breast cancer Endometrial cancer Type 2 diabetes Hypertension Obesity Adolescent risk behavior Adult height Psychosexual development
what does late puberty lead to
Cognitive and learning disabilities Self esteem Adult height Osteoporosis Psychosexual development
