14. Fundamental Mechanisms in Human Growth and Puberty Flashcards
What are the requirements for normal human growth?
What are the 3 phases of the ICP normal linear growth model? Give the growth driver too.
Why do we measure height and weight?
List 2 short stature disorders?
Absence of chronic disease, emotional stability, secure family environment, adequate nutrition, normal hormone/growth factor actions, healthy growth plates.
Infancy (nutrition). Childhood (GH, T4). Puberty (GH increase, sex steroids).
Growth is a well-established indicator of general health and well-being in children. Monitoring height and weight is useful in identifying disorders.
Growth hormone deficiency and Turner syndrome.
What three main measurements should you take of a baby/child?
What is the most common source of plotting mistake?
What do you plot on a growth chart?
What do the centiles on a growth chart show?
Weight, length (before 2yrs if concerned), height (from 2yrs). Also sitting height and head circumference for <2yrs.
Age error. Charts marked in weeks and calender months.
Age vs weight, or age vs length.
Optimum range of weights and heights. Describes the % expected to be below that line (e.g. 50% below 50th centile), half of all children between 25-75th centile.
Why was the 50th centile de-emphasised on growth charts?
How are preterm babies measured on growth charts?
How would you describe a child that falls on point A or B (below)?
Avoids confusing message to parents about perceived need for all children to be on 50th centile.
Preterm babies before 37 weeks plotted on preterm section (term birth measurements plotted at age 0, no lines between birth and 2 weeks)
A is on xth centile (if point is within 1/4 of space of the centile line). B is between centile x and y (if not within 1/4).
When do individual children need further assessment of growth than a chart?
What can child bone age assessment be used to predict?
What is the definition of short stature?
If weight/height/BMI below 0.4th centile OR if height centile is >3 centile spaces below the mid-parental centile OR a drop in height centile posiion of >2 centile spaces (as long as measurement error excluded).
Adult height.
Length/height < -2 SDS = 2.3 centile for age and sex of the appropriate refernce position.
What are the 4 aspects in evaluating short stature?
What conditions could cause disproportionate growth failure/short stature?
What 4 things could you do if growth failure/short stature was proportionate?
1) Height centile vs weight centile
2) When started (in utero/infancy/childhood/pubery)
3) Body proportions (primary or secondary growth disorder)
4) Presenting signs (ISS or specific diagnosis)
Skeletal dysplasia: achondroplasia, hypochondroplasia, rickets
Psychological assessment (psychosocial growth retardation), syndromic features - Karyotype (girls - Turner syndrome), tests for systemic disorders (chronic renal insufficiency, GI disease, nutritional deficiency), tests for endocrine disorders (hypothyroidism, hypercortisolism).
Describe the HPG axis in the male and female.
What is puberty, and how is it initiated?
What are the Tanner onset stages of puberty for girls and boys?
What stage of puberty does peak height velocity coincide with in girls and boys?
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Developmental stage when reproductive capacity attained. GnRH secretion and HPG axis re-activated. Initiated by GnRH release from hypothalamus.
Girls: breast budding + pubic hair, mean = 11yrs. Boys: testis volume >3ml + pubic hair, mean = 12yrs.
Girls: early stage. Boys: mid stage.
How is linear growth in boys and girls different?
What exerts a very strong influence on menarcheal age? What other factors are involved?
Boys: 2 additional years of prepubertal growth, taller prepubertal height, greater amplitude of growth spurt. 13.0cm difference in adult height.
Genetics. Other factors: adoption, migration, endocrine disrupting chemicals, nutrition, social? Secular trend towards earlier puberty!
