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Normal growth and regulation of children

Normal growth and regulation of children
 
main content

The growth law of alfalfa and its influencing factors

Regulation of the growth of the inferior thalamus-pituitary-GH axis

Longitudinal linear growth of the tibia

GH promotes bone growth through direct action and synergy through IGF-1

IGF-1 is the main mediator of GH growth-promoting

Effect of pulsed secretion on growth hormone
 
General law of growth

 continuity and stage  growth is a continuous process
growth Different growth rates at different ages: growth and development are not constant in all ages • The first growth peak: body length and body weight grow rapidly in the first year after birth
• The second growth peak: into adolescence, rapid growth in height and weight

 procedural (proportion of body length)  baby’s head height is 1/4 of height
After birth, the limbs grow faster than the trunk, and gradually the trunk is thick and the limbs are long.

The increase in chest circumference after birth is greater than the increase in head circumference, and the appearance of an adult body
 
General law of growth

Unbalanced development of various organs The development of various systems of the human body varies, and each has its own
The sacral nervous system develops early: the development of the brain is the fastest in the first 2 years of life, and the size and weight of the brain at age 5 is close to the adult level.
Lymphatic system: grows rapidly after birth, peaks at puberty, then gradually degenerates
 reproductive system: rapid development until puberty

 Others such as breathing, circulation, digestion, urinary, muscle

System development parallels physical growth

Unbalanced phylogeny
 
General law of growth

Individual differences

Although there are certain rules in the growth and development of children, there are considerable individual differences in genetic and environmental influences within a certain range.

Every child has its own growing “track” and will not be exactly the same. When formulating the normal value of children’s growth and development, it is often a range, not a general law of absolute value growth.

   The developmental level of individual children is relatively stable

 Definition: When no significant external environmental conditions change, the measured values ​​of each child’s growth are relatively stable in the same development level at each period, generally do not exceed the next level, and the dynamic tracking observation for more than 6 months can accurately judge the growth rate ( Growth Velocity, GV) is normal. If continuously tracking for more than 1 year, GV is lower than the 3rd percentile, and the probability of GV recovering to the 50th percentile in the following year is only 3%.
 
Characteristics of different growth stages and their regulatory factors

 Infant and young children  Rapid growth: the first peak of growth  Regulatory factors: nutrition and growth hormone
 Childhood  Stable growth
Regulatory factors: growth hormone and thyroid hormone

 puberty  rapid growth: the second peak of growth  regulatory factors: growth hormone and sex hormones
 
Characteristics of different growth stages and their regulatory factors

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Growth and development characteristics of different growth stages

 Infant (0-3 years old)

 fast growth

• Infancy (0-1 years), including the neonatal period (0-28 days), is the fastest growing phase of a person’s life.
• Increased body length by up to 25 cm in the first year after birth

Growth regulation

• Based on nutrition regulation mode within 6 months

• 6 months to 1 year old GH axis begins to promote growth

• After 1 year of age, the main regulation of auxin axis
 
Characteristics of different growth stages and their regulatory factors
 
Characteristics and regulatory factors of different growth stages

Childhood (3-10 years old)

Stable growth

• Includes pre-school (3-6 or 7 years old) and school-age (6 or 7 to 11 or 12 years old) • GV declines and is relatively stable at 5-7 cm/y
• GV does not continue to average speed, and the speed can fluctuate in the same year. • Normal children’s height growth rate after 4 years of age begins to decrease year by year, reaching a minimum before puberty, about 5~5.5 cm/year.
Growth regulation

• Growth hormone and thyroxine are major regulators of childhood growth

• Influenced by genetics, nutrition, mental state, etc.

Estimation formula for 2~10 years old: height (cm) = age (years) 7 + 70
 
Characteristics of different growth stages and their regulatory factors

age)
 
Characteristics and regulatory factors of different growth stages

 puberty (10-18 or 20 years old)

• Adolescence: refers to the transition from the beginning of secondary sexuality to the complete maturity of sexual development, which is a transition from child to adult.
• Boy testicular development, girl mammary gland development is a sign of puberty.

• The starting age depends on the activation of the hypothalamic-pituitary-gonadal axis function sooner or later. • Girl: 10~12 years old
• Boy: 12~14 years old, 2 years later than girl

• Average puberty lasts for 6 to 7 years (second growth peak) • Growth regulation: co-regulation by GH axis and gonadal axis
 
Adolescent growth

• Adolescence: The second peak of growth – Growth mode:
Deceleration-acceleration-sudden peak-deceleration-stop growth
• In three phases – the starting phase:
GV can be reduced to the lowest point, 4~5 cm/y – peak speed stage (PHV): Female: 7-8cm/y, male: 9-11cm/y

Deceleration phase
 
Adolescent growth and adult height

 Contribution to adult adult height (FAH):

– Girls: 15%, a total length of 20-25 cm, a lifetime high growth rate after menarche

About 5~7cm (ranging from 1~11cm)

– Boy: 18%, a total length of 28~30 cm
 
Girl sexual development

• Normal adolescent progression
• Girls about 1 year per breast period
• B2 menarche 2.99±1.07 years (about 3 years) • B2 FAH 4.80±0.85 years (about 5 years)
 
Breast and pubic hair development staging

breast

Pubic hair
 
Boy sexual development
 
Testicular, penile and pubic hair development staging
 
Characteristics of different growth stages and their regulatory factors

The growth law of alfalfa and its influencing factors

Regulation of the growth of the inferior thalamus-pituitary-GH axis

Longitudinal linear growth of the tibia

omnitrope HGH promotes bone growth through direct action and synergy through IGF-1

IGF-1 is the main mediator of GH growth-promoting

Effect of pulsed secretion on growth hormone
 
Height growth is mainly achieved by longitudinal linear growth of the bone

Before the epiphyseal plate is closed, after the epiphyseal plate is closed
 
Standard bone age tablets
 
main content

The growth law of alfalfa and its influencing factors
Regulation of the growth of the inferior thalamus-pituitary-GH axis

Longitudinal linear growth of the tibia

GH promotes bone growth through direct action and synergy through IGF-1

IGF-1 is the main mediator of GH growth-promoting effect. The effect of  pulsed secretion on growth hormone
 
Direct action
 
Factors affecting growth hormone secretion

• Lack of energy supply (1) Low blood sugar (2) Hunger (3) Exercise
• Increased plasma amino acid levels, especially arginine

• Stressful stimuli: surgery, trauma, blood pressure, etc. • Sleep, especially during deep sleep
 
Growth hormone secretion characteristics

Pulsed secretion
• The fluctuations in day and night are large, and when the low peak is secreted, it is difficult to measure in the blood circulation. • Frequency nights are more than during the day.
• There are about 6 to 8 pulses in pre-puberty and puberty within 24 hours, about every 3 to 4 hours. • During the middle of puberty, the secretion pulse is the largest and the secretion is the most.
• Pulse number and amplitude are related to age within 24 hours. Circadian rhythm
Normal people have a peak of secretion about 1 hour (45~90min) after going to sleep, and the secretion is more than half of the total amount of the whole day. If the sleep time changes, the GH peak appearance time also changes accordingly.
 
Growth-promoting effects • Promote liver synthesis of IGF-1
• Stimulates collagen synthesis, cartilage formation, causing accelerated linear growth and bone broadening; small effect on bone maturity
• Increase the size and number of somatic cells • Stimulate the growth of all organs and tissues. Effect on metabolism • Promote protein synthesis • Promote fat breakdown
• Glucose
 
main content

The growth law of alfalfa and its influencing factors
Regulation of the growth of the inferior thalamus-pituitary-GH axis

Longitudinal linear growth of the tibia

GH promotes bone growth through direct action and synergy through IGF-1

IGF-1 is the main mediator of GH growth-promoting

Effect of pulsed secretion on growth hormone
 
IGF-1 is the main mediator of GH’s physiological role

IGFs are a class of multifunctional hormones similar in structure to insulin, which regulate cell proliferation, differentiation and metabolic activity.
GH promotes linear growth through direct action or IGF-1 mediated in vitro cartilage culture test
• GH + pituitary rat cartilage culture → cartilage non-growth • GH + normal animal plasma culture → cartilage growth
• Explain that GH acts through a factor in normal animal plasma and later confirms that the substance is IGF-1
 
The main influencing factors of IGF-1

GH: rises as GH rises

Insulin: Synergistic GH promotes elevation of IGF-1

 Nutritional status: poor nutritional status leads to decreased IGF-1 production

 Age: Increase with age, peak at puberty, and gradually decline after adulthood

 puberty: peak IGF-1 levels during adolescence
 
GH-IGF-IGFBP axis regulates growth

IGFBP3 regulates its distribution and clearance rate in vivo by binding to IGF-1

IGFBP3 binds to IGF-1, an unstable subunit (ALS) glycoprotein, to form a larger molecular weight (150 kDa) ternary complex, thereby prolonging the half-life of IGF-1 and maintaining stable IGF-1 levels in the blood.
 
main content

The growth law of alfalfa and its influencing factors

Regulation of the growth of the inferior thalamus-pituitary-GH axis

Longitudinal linear growth of the tibia

GH promotes bone growth through direct action and synergy through IGF-1

IGF-1 is the main mediator of GH growth-promoting

Effect of pulsed secretion on growth hormone
 
GH is pulsed secretion

GH is pulsed, but not a single pulse. There are more than 7 important pulses throughout the day, including 3 to 4 times during late deep sleep, about 2 hours apart.
Pulsed secretion of GH is affected by GHRH pulsed secretion

24-hour secretion rhythm of growth hormone
 
GH efficacy does not depend on GH pulsed release

 Daily single injection of GH does not really simulate human GH multiple pulse secretion. 多次 Simulated human physiologic pulse multiple GH injection is not feasible in clinical practice.
 Foreign approved GH use is not required to be used once a day, and the guiding dose is mainly determined by weeks, indicating that the simulated pulse is not the key to GH growth-promoting
 
to sum up

  1. Children have their own specific laws and have different characteristics at different stages of growth.
  2. Hypothalamic-pituitary-GH axis is the main endocrine system that regulates linear growth
  3. IGF-1 is an important mediator of GH to promote growth
  4. The physiological role of GH does not depend on its pulsed secretion.

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