Growth hormone (GH) is a peptide hormone secreted by the pituitary gland. It is responsible for the growth, reproduction, and regeneration of cells during childhood; it also maintains the healthy growth of tissues and organs throughout all stages of life.

Growth hormone stimulates the growth of all body tissues, including bones. Secretion levels rise gradually during childhood and reach their peak during the growth spurt that occurs at puberty. It is the primary driver for increasing height in children and adolescents, as it exerts a powerful anabolic effect on cells.

Functions of Growth Hormone (GH)

• Metabolic Regulation: It provides tissues with the energy required for anabolism by acting as an insulin antagonist (counter-regulatory to insulin).
• Protein Synthesis: It stimulates protein anabolism and amino acid uptake by cells.
• Lipolysis: It promotes the breakdown of lipids (fats) to be used as an energy source.
• Immune System Support: It enhances and stimulates the immune system response.
• Muscle Mass: It promotes an increase in skeletal muscle mass.

Secretion of Growth Hormone (GH)

Growth hormone is secreted in pulsatile bursts occurring every three to five hours. Its levels significantly rise during sleep, physical exercise, and periods of physiological stress, as well as in response to hypoglycemia (low blood glucose). Furthermore, GH secretion peaks during puberty, whereas it tends to decrease during pregnancy.

Growth Hormone Deficiency (GHD)

Children with Growth Hormone Deficiency (GHD) typically exhibit normal growth patterns during the first two years of life. However, growth velocity significantly decreases or may cease entirely between the ages of two and three. It is important to note that a child's short stature or slow growth does not definitively indicate GHD; growth should be monitored and assessed using standardized growth charts.

Symptoms of Growth Hormone Deficiency

The primary clinical manifestations include short stature or dwarfism. In some instances, dwarfism may be classified as psychosocial dwarfism (also known as emotional deprivation dwarfism). This condition results from severe emotional deprivation; once the child's emotional environment and psychological well-being improve, GH levels typically return to their normal physiological range.

Etiology of Growth Hormone Deficiency (GHD) in Children

The causes of GH deficiency can be categorized as follows:

• Congenital/Genetic Factors: Structural damage to the pituitary gland or the hypothalamus during fetal development.
• Damage or deficiency that occurs postnatally (after birth) due to external factors such as trauma or infection.
• Mutations in the genes responsible for the synthesis and secretion of Growth Hormone. These mutations may also lead to Combined Pituitary Hormone Deficiency (CPHD), affecting other pituitary hormones.
• Secondary deficiency resulting from insufficient secretion of Growth Hormone-Releasing Hormone (GHRH) from the hypothalamus.
• Inability of the somatotropic cells (somatotrophs) in the anterior pituitary to produce the hormone.
• Defective molecular structure of the synthesized GH, leading to bioinactive growth hormone with reduced biological activity and minimal impact on growth.

Clinical Manifestations of Growth Hormone Deficiency (GHD) in Children

• The child appears significantly shorter than peers of the same age and sex (falling below the 3rd percentile on growth charts).
• The child's bone age (skeletal maturation) lags behind their chronological age when assessed via X-ray.
• Children often present with a "chubby" appearance or central obesity (increased body fat, especially around the waist).
• Characterized by thin, sparse, or slow-growing hair.
• A significant delay in the onset of secondary sexual characteristics and the pubertal growth spurt

Treatment of Growth Hormone Deficiency (GHD) in Children

The primary treatment for GHD involves Growth Hormone Replacement Therapy, administered via subcutaneous injections to promote linear growth. Clinical response to this therapy varies significantly depending on the underlying etiology:

• Children with diagnosed growth hormone deficiency typically show a robust response to replacement therapy, often achieving their predicted target adult height.
• A specific subset of children with genetic mutations that prevent endogenous GH production may develop neutralizing antibodies against the exogenous hormone injections, which can inhibit the treatment's effectiveness.
• Children with short stature not caused by a hormonal deficiency may still show a positive growth response when treated with pharmacological (high) doses of growth hormone.