Growth hormone (applied physiology)

Book recommended: Medical Physiology by Jaypee

1. Growth Hormone (Applied Physiology) Danish Hassan Lecturer, University of sargodha

2. Growth Hormone Hyper-secretion Gigantism Acromegaly Acromegalic -gigantism Hypo-secretion Dwarfism Acromicria Simmond Disease

3. Gigantism Pituitary disorder characterized by excess growth of the body. The subjects look like the giants with average height of about 7 to 8 feet

4. Causes: Due to hyper-secretion of GH in childhood or in pre-adult life before the fusion of epiphysis of bone with shaft. Hyper-secretion of GH is because of tumor of acidophil cells in the anterior pituitary

5. Signs and symptoms General overgrowth of the person leads to the development of a huge stature, with a height of more than 7 or 8 feet. The limbs are disproportionately long Giants are hyperglycemic and they develop glycosuria and pituitary diabetes.

6. Hyperglycemia causes constant stimulation of β-cells of islets of Langerhans in the pancreas and release of insulin which leads to degeneration of these cells and deficiency of insulin and ultimately, diabetes mellitus is developed Tumor of the pituitary gland itself causes constant headache Pituitary tumor also causes visual disturbances. It compresses the lateral fibers of optic chiasma , leading to bitemporal hemianopia

7. Acromegaly Disorder characterized by the enlargement, thickening and broadening of bones, particularly in the extremities of the body.

8. Causes: Hypersecretion of GH in adults after the fusion of epiphysis with shaft of the bone. It is because of tumor of acidophil cells in the anterior pituitary

9. Signs and symptoms Acromegalic /gorilla face Face with rough features Protrusion of supraorbital ridges Broadening of nose Thickening of lips Thickening and wrinkles formation on forehead Prognathism (protrusion of lower jaw)

10. Enlargement of hands and feet Kyphosis Thickening of scalp (bulldog scalp) Overgrowth of body hair Enlargement of visceral organs such as lungs, thymus, heart, liver and spleen ( Organomegaly ) Hyperactivity of thyroid, parathyroid and adrenal glands

11. Hyperglycemia and glucosuria , resulting in diabetes mellitus Hypertension Headache Visual disturbance ( bitemporal hemianopia ).

12. Acromegalic Gigantism Rare disorder with symptoms of both gigantism and acromegaly . Causes: Hypersecretion of GH in children, before the fusion of epiphysis with shaft of the bones causes gigantism and if hypersecretion of GH is continued even after the fusion of epiphysis , the symptoms of acromegaly also appear.

13. Treatment Treatment consists of administration of long-acting somatostatin analogues. Surgical removal of the tumor in cases that do not respond to medical treatment. There are also GH receptor antagonists currently available that can be used to treat the symptoms of GH excess.

14. Dwarfism Pituitary disorder in children, characterized by the stunted growth.

15. Causes: Reduction in GH secretion in infancy or early childhood causes dwarfism. It occurs because of the following reasons: Tumor of chromophobes , which compresses and destroys the normal cells secreting GH Deficiency of GH-releasing hormone secreted by hypothalamus Deficiency of somatomedin C Atrophy or degeneration of acidophilic cells in the anterior pituitary

16. Pan- hypopituitarism Reduction in the secretion of all the hormones of anterior pituitary gland. This type of dwarfism is associated with other symptoms due to the deficiency of other anterior pituitary hormones

17. Signs and symptoms: Primary symptom of hypopituitarism in children is the stunted skeletal growth. Max height of anterior pituitary dwarf at the adult age is only about 3 feet Proportions of different parts of the body are almost normal. Only the head becomes slightly larger in relation to the body Pituitary dwarfs do not show any deformity and their mental activity is normal with no mental retardation

18. Reproductive function is not affected, if there is only GH deficiency. However, during panhypopituitarism , the dwarfs do not obtain puberty due to the deficiency of gonadotropic hormone.

19. Laron dwarfism: Genetic disorder, also called GH insensitivity. It occurs due to the presence of abnormal growth hormone secretagogue (GHS) receptors in liver. GHS receptors become abnormal because of the mutation of genes for the receptors. GH secretion is normal or high. But the hormone cannot stimulate growth because of the abnormal GHS receptors

20. Psychogenic Dwarfism Dwarfism occurs if the child is exposed to extreme emotional deprivation or stress. The short stature is because of deficiency of GH. This type of dwarfism is called psychogenic dwarfism, psychosocial dwarfism or stress dwarfism

21. Dwarfism in dystrophia adiposogenitalis Also called Fröhlich syndrome It is a condition which may be caused by decreased levels in GnRH in the blood It is characterized by: Growth retardation  Retarded sexual development Atrophy or  hypoplasia  of the gonads Altered secondary sex characteristics

22. Dwarfism in Panhypopituitarism Panhypopituitarism is the pituitary disorder due to reduction in secretion of all anterior pituitary hormones. These dwarfs do not attain puberty due to reduced production of sex hormones from the anterior pitutary .

23. Acromicria Acromicria is a rare disease in adults characterized by the atrophy of the extremities of the body.

24. Causes Deficiency of GH in adults causes acromicria Secretion of GH decreases in the following conditions: Deficiency of GH-releasing hormone from hypothalamus Atrophy or degeneration of acidophilic cells in the anterior pituitary Tumor of chromophobes Panhypopituitarism

25. Signs and symptoms Atrophy and thinning of extremities of the body, (hands and feet) are the major symptoms in acromicria Mostly associated with hypothyroidism Hyposecretion of adrenocortical hormones also is common in acromicria The person becomes lethargic and obese There is loss of sexual functions

26. Simmond Disease A disease ascribed by destruction or physiological exhaustation of the cells of anterior pituitary. A rare pituitary disease. Also called pituitary cachexia .

27. Causes It occurs mostly in panhypopituitarism , i.e. hyposecretion of all the anterior pituitary hormones due to the atrophy or degeneration of anterior pituitary

28. Symptoms A major feature of Simmond disease is the rapidly developing senile decay, a 30-years-old person looks like a 60-years-old person. The senile decay is mainly due to deficiency of hormones from target glands of anterior pituitary, i.e. the thyroid gland, adrenal cortex and the gonads Loss of hair over the body and loss of teeth Skin on face becomes dry and wrinkled. So, there is a shrunken appearance of facial features.

29. Sheehan Syndrome A condition that can occur in a woman who bleeds severely during childbirth. Severe blood loss and decreased blood flow (ischemia) of the pituitary can also lead to pituitary insufficiency. It is manifested as: Hypothyroidism Adrenal insufficiency Hypogonadism (failure to resume normal menses) GH deficiency

30. Case Senario A middle-aged male patient consults his family physician because he has noticed that his hat and wedding ring are tight and his shoe size has increased one size during the past couple of years. He complains of joint aches and pains. He also states that he has noticed his voice getting deeper and his facial features being thicker and coarser when compared to his pictures of 10 years ago.

31. Laboratory values show increased growth hormone and IGF-I levels and increased fasting plasma glucose. An intravenous infusion of glucose fails to decrease growth hormone levels. Brain MRI reveals a tumor localized to the pituitary.

32. Q: What is you most probable diagnosis? Q: Give 05 evidence to support your diagnosis? Q: What are the lab investigations that you might order to confirm your diagnosis?