SM_194b: Growth and Development Flashcards
Phases of growth are ____, ____, and ____
Phases of growth are fetal, infancy and childhood, and adolescent
Normal intrauterine growth is largely ___ of the fetal pituitary gland hormones
Normal intrauterine growth is largely independent of the fetal pituitary gland hormones
- At midgestation, fetus grows 2.5 cm/week
- Prenatal growth is controlled by different mechanisms than postnatal growth
____ is the main source of nutrition and oxygen to the fetus
Placenta is the main source of nutrition and oxygen to the fetus
- Abnormal implantation, vascular insufficiency, infarction can compromise supply of oxygen and nutrients to fetus
Maternal influences on fetal growth are ___, ___, and ___
Maternal influences on fetal growth are malnutrition, hypertension, and drugs / alcohol
Endocrine regulators of fetal growth are ____, ____, ____, and ____
Endocrine regulators of fetal growth are insulin, insulin-like growth factors (IGF-I, IGF-II), thyroid hormone, and growth hormone
___ is the major endocrine regulator of fetal growth
Insulin is the major endocrine regulator of fetal growth
Infants of diabetic mothers are born large
Infants with leprechaunism are born small for gestational age
Local production of ___ is critical for normal intrauterine growht
Local production of insulin-like growth factors (IGF-I and IGF-II) is critical for normal intrauterine growht
Newborns with congenital hypothyroidism or GH deficiency are usually ___ size at birth
Newborns with congenital hypothyroidism or GH deficiency are usually normal size at birth
Postnatal growth is influenced by ____, ____, ____, ____, and ____
Postnatal growth is influenced by nutrition, metabolic, hormones, genetics, and psychosocial factor
____ and ____ are major endocrine regulators of growth in infancy and childhood
Thyroid hormone and GH are major endocrine regulators of growth in infancy and childhood
Thyroid hormone has ____ and ____ in infancy and childhood
Thyroid hormone has direct effect on epiphyseal cartilage and permissive effect on GH secretion in infancy and childhood
- Epiphyseal cartilage: chondrocyte proliferation, epiphyseal fusion
GH is secreted from ____, in ____ fashion, with greatest amplitude ____, and regulated by ____ and ____
GH is secreted from anterior pituitary somatotrophs, in pulsatile fashion, with greatest amplitude overnight, and regulated by GHRH (+) and somatostatin (-)
Describe the GH / IGF-1 axis
GH / IGF-1 axis
- Hypothalamus secretes GHRH
- Pituitary secretes GH
- Acts on GH receptor on target tissue and IGF-1 receptor on bone
GH acts on ___, ___, ___, and ___
GH acts on bone, linear growth, adipose tissue and muscle
- Increases osteoclast differentiation and activity, increases osteoblast activity, increases bone mass by endochondral bone formation
- Promotes epiphyseal growth, stimulates differentiation of prechondrocytes and focal expression of IGF-1
- Increases lipolysis, decreases lipogenesis
- Increases amino acid transport, increases nitrogen retention, increases lean tissue, and increases energy expenditure
GH primarily functions to ____ in childhood via ____ and ____
GH primarily functions to promote linear growth in childhood via directn effect on bone and indirectly by stimulating IGF-1 production
IGF-1 is ___, is produced based on ___, and is responsible for ___
IGF-1 is the most important IGF for postnatal growth, is produced based on GH secretion, and is responsible for stimulating muscle and cartilage growth
- Rises significantly during puberty
- Critical mediators of growth
____ is the main carrier of IGF-1 in the body
IGFBP-3 is the main carrier of IGF-1 in the body
Puberty is regulated by the ____
Puberty is regulated by the hypothalamic-pituitary-gonadal axis
- Sex steroids, estrogen, and testosterone produce the physical changes of puberty and promote the growth spurt
Measure length / height at age 0-2 ___
Measure length / height at age 0-2 supine
Measure length / height at age 2+ ___
Measure length / height at age 2+ standing up
- At age 2, length typically 1 cm longer than standing height
- Height percentile may decreases at age 2 due to a change in measurement technique
Describe growth measurements
Growth measurements
- Can also measure arm span, upper segment and lower segment, upper to lower segment ratios
- Other helpful tools include: mid-parental height (target height) and bone age
Mid-parental height for girls = _____
Mid-parental height for girls =
[(paternal height - 5 in) + maternal height] / 2
Mid-parental height for boys = ____
Mid-parental height for boys =
[Paternal height + (maternal height + 5 in)] / 2
Describe growth rate
Growth rate
- Poor correlation between birth height and adult height, improves by age 2
- 2/3 of all children will cross growth percentiles in the first 2 years of life
- Peak growth rates occur in 1st year of life and during puberty
Describe red flags for growth
Red flags for growth
- Height < 3rd percentile
- Height significantly below genetic potentional
- Abnormally slow growth rate
- Downwardly crossing percentile channels after 18 months - 2 years of age
Short stature is ____
Short stature is height SDS < -2 for age and sex
- Approximately 3% of all children
- Does not automatically imply pathology
Short stature is classified as ____, ____, and ____
Short stature is classified as primary growth abnormalities, secondary growth disorders, and idiopathic short stature
Primary growth abnormalities (intrinsic growth plate abnormalities) can be caused by ____ or ____
Primary growth abnormalities (intrinsic growth plate abnormalities) can be caused by osteochondrodysplasias (skeletal dysplasias) or chromosomal abnormalities
- Chromosomal abnormalities: Down’s syndrome, Turner syndrome, Russel-Silver syndrome
In primary growth abnormalities, linear growth rate can be ____ or ____
In primary growth abnormalities, linear growth rate can be normal but below the typical growth curve or be normal then slow
- Skeletal age = chronologic age
Describe secondary growth disorders
Secondary growth disorders
- Disorders of the GH-IGF axis
- Other endocrine disorders: Cushing’s, hypothyroidism
- Malnutrition
- IUGR
- Chronic diseases
- Psychosocial disorders
- Inflammatory disorders
In secondary growth disorders, linear growth is ____ and ____
In secondary growth disorders, linear growth is slow and skeletal age is delayed
- Bone age < chronologic age
Endocrine causes of short stature are ____, ____, and ____
Endocrine causes of short stature are hypothyroidism, glucocorticoid excess, and IGF deficiency
- IGF deficiency: hypothalamic dysfunction, pituitary GH deficiency, and GH resistance
In hypothryoidism, there will be ____ and ____
In hypothryoidism, there will be profound growth deceleration / failure and delayed puberty (except Van Wyk Grumbach Syndrome)
Glucocorticoid excess ___
Glucocorticoid excess suppresses GH and IGF-1 action at the growth plate
- Causes: Cushing’s Disease (pituitary ACTH hypersecretion), cortisol secreting tumor, CRH secreting tumor, exogenous
Describe presentation of glucocorticoid excess
Glucocorticoid excess presentation
- Central obesity
- Buffalo hump
- Purple / red abdominal striae
- Round face
- Easy bruising
- Linear growth failure
- Plethora / reddish face
- Osteopenia
- Depression
GH deficiency can result from ____ or ____
GH deficiency can result from hypothalamic dysfunction (impaired GHRH release) or pituitary GH deficiency
Describe presentation of GH deficiency
GH deficiency presentation
- Round, cherubic face
- Truncal obesity
- Small hands / feet
- Neonatal hypoglycemia, prolonged jaundice, or micropenis
- Hx of cranial irradiation or chemo
- Midline defects
- High-pitched voice
IGF deficiency is ___ or ___
IGF deficiency is GH resistance (Laron syndrome) or primary defects of IGF-1 synthesis
Laron syndrome is ____ caused by ____ or ____
Laron syndrome is GH resistance caused by abnormalities of the GH receptor and postreceptor abnormalities of GH signal transduction
Describe non-pathologic causes of short stature
Non-pathologic causes of short stature
- Genetic or familial short stature: bone age = chronological age
- Constitutional delay of growth and puberty: bone age < chronological age
