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Endocrine problems of the child and the adolescent.
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Height is determined by multiple factors among which heredity is the most important. When we say heredity we do not mean one gene. Many genes are involved most of which have not been mental factors can modify the genetically determined potentials for somatic growth.
Among the environmental factors, malnutrition, frequent infections or deranged psychosocial environment may adversely affect somatic growth.
Hence short stature can be caused by many pathologic conditions genetic or acquired. |
| Hormonal effects on growth |
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Hormones play a vital role in height determination.
1. GROWTH HORMONE (GH) constitutes the main hormonal factor. It is synthesized and secreted by the pituitary gland which is situated on the base of the brain. GH synthesis and secretion is regulated by two other hormones secreted by the hypothalamus which lies above the pituitary. These two hypothalamic hormones have opposing actions on the pituitary : Somatostatin inhibits the secretion of GH while the growth hormone releasing hormone increases its secretion. Deficient production of GH leads to short stature. Deficient production may be caused be genetic factors or other factors like tumor, irradiation or even head injury.
2. THYROXIN This hormone is produced by the thyroid gland which is situated on the base of the neck. A hormone called thyroid stimulating hormone (TSH) is secreted by the pituitary gland and stimulates the thyroid leading to thyroxin synthesis and secretion. Thyroid has many function but one of them is to stimulate growth and maturation of the so called growth plate, the part of the bone from which longitudinal bone growth takes place. THYROXIN DEFICIENCY leads not only to impaired somatic growth (short stature) but also in disturbances in mental development and function.
3. Sex hormones (estrogens and androgens). Estrogens are the female hormones and are primarily secreted by the ovaries, while androgens primarily testosterone are the male hormones, which are predominantly secreted by the testes. Androgens promote bone growth but at the same time they speed up the closure of the bones.
The sex hormones which are secreted during puberty are responsible for the spurt of growth which boys and girls experience during puberty. |
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In 1958 Turner first described a combination of signs like short stature, ovarian insuffiency with resultant abnormalities of pubertal development. Some of the girls with TS also have heart and kidney problems. This combination of derangments is caused by numerical or structural a defect of one of the sex chromosomes. In general the chromosomes carry the genes which determine all our characteristics. In man the chromosomes are 46, two of which are the so called sex chromosomes. Turner syndrome is encountered in 1 out of 2500 girls. Some girls with this problem have fewer clinical characteristics and other have more severe picture. Growth hormone is currently used for improvement of growth and estrogens are given at the appropriate age to substitute for the ovarian insufficiency and thus promote pubertal development. |
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Hypothyroidism is a term used for a clinical condition caused by deficient production of the thyroid hormones (thyroxin and triidothyroxine). Hypothyroidism has many causes: 1. Agenesis of the thyroid (the thyroid gland was never born), 2. hypoplasia (the gland is smaller and malfuctioning), 3. enzymatic defect. The thyroid gland is usually increased in size but cannot make enough thyroxin. This form of hypothyroidism is hereditary, 4. Iodine deficiency. The thyroid gland is normal but does not have the iodine needed for thyroxin synthesis, 5. Hashimoto thyroiditis. A form of mild inflammation which is caused by antibodies produced by the organism.
In a hypothyroid individual all functions in the body are very slow including those of the brain. In the baby one sees a big tongue, depressed nasal bridge, a puffy face, short neck, omphalocele, show growth, poor feeding, hoarse crying and developmental delay. In the older child one may see slow growth, mild obesity, sluggish behavior dry, pale skin with or without a swelling (goiter) in the base of the neck. Some times the hypothyroidism is caused by a defect in the pituitary and not in the thyroid gland. |
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