189. Growth and development Flashcards
Causes:
- Cushing’s Disease: pituitary ACTH hypersecretion
- Cortisol secreting tumor
- CRH secreting tumor
- Exogenous (high dose steroids)
Suppress GH and IGF-1 action at the growth plate
- slow linear growth with weight gain acceleration
Glucocorticoid excess
In hypothyroidism:
- in addition to typical symptoms you will also see profound growth deceleration/failure and __ puberty
Delayed
Most important in the first few months (up to about 9 months) when it comes to postnatal growth
Nutrition
Secretion affected by:
- thyroid hormone
- estrogen
- glucocorticoids
- androgens
- IGF-1
GH
Newborns with congenital hypothyroidism or growth hormone deficiency are usually __ at birth
Normal size
Disorders of the GH-IGF axis
Other endocrine disorders:
- Cushing’s
- Hypothyroidism
Malnutrition
IUGR
Chronic diseases
Psychosocial disorders
Secondary Growth Disorders
Growth hormone action:
- Increases lipolysis
- Decreases lipogenesis
Make __ into lean tissue
Adipose tissue
Hormone that leads to:
- bone growth directly (2 routes)
- Inhibition of IGF-1 negative feedback pathway
- increase secretion of GH from pituitary
Estrogen
At midgestation, fetus grows how much per week?
2.5 cm
Growth hormone action at the level of __:
- increases AA transport
- Increases nitrogen retention
- Increases lean tissue
- Increases energy expenditure
Muscle
Hypothalamic dysfunction –> impaired GHRH release
- congenital malformations
- trauma
- inflammation
- CNS tumors
- cranial irradiation
GH deficiency
Binding of what molecule to its receptor at the bone level leads to growth
Synthesized in the liver
IGF-1
In secondary growth disorders:
- linear growth is __ throughout
Skeletal age (bone age) __ chronologic age
Slow
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Endocrine regulators of growth
- local production critical for normal intrauterine growth
Prenatal role in humans not completely delineated
- mice with knockouts have birth weights 60% of normal
IGF-1 and IGF-2
Definition:
- more than 2 standard deviations below for sex and age
- 3% of all children
- does not automatically imply pathology
Short stature
Critical mediator of growth
- rises significantly during puberty
Largely responsible for stimulating muscle and cartilage growth
IGF-1
Children grow in a remarkably __ manner
Any deviation from this pattern should raise concern
Predictable
Secreted in a pulsatile manner, greatest amplitude overnight
Regulated by:
- GHRH (+)
- somatostatin (-)
Secretion affected by:
- exercise
- sleep patterns
- food intake: ghrelin
- age and pubertal status
- body composition
- emotional factors
- various other neurotransmitters
GH
Peak growth rates occur during the __ __ of life and during puberty
- 0-12 months: 25 cm/yr
- 12-24 months: 12.5 cm/yr
- 2 yrs - puberty: 6-8 cm/yr
- pubertal peak: 9-10 cm/yr
First year
The major endocrine regulator of fetal growth
- infants of diabetic mothers are born large bc glucose crosses placenta
Insulin
3 phases of growth
- Fetal (in utero)
- Infancy and childhood
- Adolescence
Girls: ((Dad’s height - 5 inches) + mom’s height)/2
Boys: (Dad’s height + (mom’s height + 5 inches))/2
Mid parental height
Idiopathic short stature:
Genetic or familial short stature is cases in which bone age __ chronological age
Constitutional delay of growth and puberty (late bloomers) is cases in which bone age __ chronological age
=
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What kind of growth chart do you use for 2-20 year olds?
CDC
In primary growth abnormalities:
- linear growth rate can be:
- -> __ , but below the typically growth curve
- -> __ , but then slows down
Skeletal age (bone age) __ Chronologic age
Normal
=
IGF won’t get transported through blood effectively without __
IGFBP
Direct effect on epiphyseal cartilage
- chondrocyte proliferation
- epiphyseal fusion
Permissive effect on growth hormone secretion
- increases GH release
Thyroid hormone
Endocrine causes of short stature (3 types)
Hypothyroidism
Glucocorticoid excess
IGF deficiency
What kind of growth chart do you use for 0-2 year olds?
WHO
Main source of nutrition and oxygen to the fetus
Abnormal implantation, vascular insufficiency, infarction can compromise supply of oxygen and nutrients to the fetus
Placenta
Growth hormone action:
- Promotes epiphyseal growth
- GH stimulates differentiation of prechondrocytes and local expression of IGF-1
Linear growth
Combination of hypothyroidism, precocious puberty, and ovarian cysts in girls
Van Wyk Grumbach syndrome
Infants with __ are born small for gestational age d/t insulin resistance
Leprechaunism
Some features of __:
- round, cherubic face
- truncal obesity
- small hands/feet
- neonatal hypoglycemia, prolonged jaundice, and/or micropenis
- Hx of cranial irradiation or chemotherapy
- Midline defects
- High pitched voice
GH deficiency
What position is a 2+yo when you measure their height?
Standing up
Puberty is regulated by the __ axis
Sex steroids, estrogen, and testosterone produce the physical changes of puberty and promote the growth spurt
HPG (hypothalamic-pituitary-gonadal)
aka Intrinsic Growth Plate Abnormalities
Osteochondrodysplasias
Chromosomal abnormalities
- Down’s Syndrome
- Turner Syndrome
- Russel-Silver Syndrome
Primary Growth Abnormalities
Major endocrine regulators of growth in infancy and childhood
Thyroid hormone
Growth hormone
What position is a 0-2yo when you measure their height?
Supine
Growth hormone action:
- increases osteoclast differentiation and activity
- increases osteoblast activity
- increases bone mass by endochondral bone formation
Bone metabolism
When checking bone age, you take an XR of the __ __
Left hand
Normal intrauterine growth is largely __ of the fetal pituitary gland hormones
independent
Deviation from a __ __ __ can be the first manifestation of a wide variety of disease processes
Normal growth pattern
Height < 3rd percentile
Height significantly below genetic potential
- just bc they’re on the growth curve doesn’t mean they are growing the way they should
Abnormally slow growth rate
Downwardly crossing percentile channels after 18 months - 2 years of age
Red flags for growth
Nutritional obesity has normal growth or accelerated from increased __ acting on IGF-1 receptors
Insulin
