Oncological and Other Deceases of Pituitary Gland - Essay Example

DISEASES OF THE PITUITARY GLAND Date: 14-02-2010 Class: Instructors Name: The pituitary gland is a very important gland in the human body which is divided into two parts that is the anterior and the posterior lobe. The gland is found within sella turcica which is an empty space at the end of the brain. The anterior lobe of the gland has mainly five cell types which include the somatotrope, lactotrope, corticotrope, thyrotrope and gonadotrope cells. These cells release hormones which are the growth hormone, prolactin, adrenocorticotropic hormone, thyroid stimulating hormone and the leutinizing hormone and follicle stimulating hormone respectively. The gland triggers release of the hormones mainly by stimulus from hypothalamus and the gland is important because it affects many bodily functions and it has great effects on other glands within the body. An increase in the secretion of the hormones of the pituitary gland is known as hyperpituitarism. This pathology mainly occurs due to the occurrence of an adenoma. Particularly this adenoma occurs in the cells of the anterior pituitary. An adenoma of the lactotroph or mammotroph cells of the anterior pituitary, which are responsible for the secretion of prolactin, is the most widely occurring type of adenoma which affects the gland. The adenoma is referred to as a prolactinoma and it is seen in 30 percent of the reported cases of adenomas of the pituitary gland. The prolactinomas can be of varying sizes and the lactotrophic cells may stain very weakly or very intensely. The greater the size of the adenoma, the greater will be the secretion of prolactin and the same is true for the converse. Small adenomas are known as microadenomas whereas large tumors are referred to as macroadenomas. The diagnosed cases mainly present with microadenomas. These tumors also have a tendency to undergo quick necrosis. This pathology is more easily detected in females than in males. The diagnosed female cases are mostly in the age group between 20 and 40. The reason behind the higher female diagnosis rate is that they mainly present with disturbances in their menstrual cycle as a result of the high levels of prolactin in the blood. This allows for a quick diagnosis. Small size adenomas of the glands can be hence comparatively easily diagnosed in the females during these ages. On the other hand, in females after the age of menopause and in males, the adenomas are found when they have mostly increased in their sizes because of the delay in the diagnosis. The tumors of the lactotroph cells also do not have a very fast progression rate. The tumor is responsible for the increased levels of prolactin in the blood. This leads to cessation of menstrual cycle in females as well as galactorrhea. In males galactorrhea along with the loss of sexual desire and impotence is seen in the disease presentation. Galactorrhea manifestation is mainly seen in females than in the males. In 90 percent of the females with this condition loss of menstrual cycle or irregularities in the menstrual cycle as well as the loss of fertility is seen. Females with high levels of prolactin have a deficiency of estrogen. This deficiency can lead to a subsequent reduction in the lubrication of vagina and it results in disorders of the bone. Growth of hair on the face is also seen. Females can also present with psychiatric disorders and they show an increase in their weight as well. The presentation in males includes impairment in sexual function with loss of fertility as well. High prolactin levels lead to a decrease in the levels of the male sex hormone testosterone. In males the disease is diagnosed at later stages when the tumor has reached to a considerable size and they mainly present with heavy headaches, damage to the pituitary gland and disturbances in vision. The prolactinomas should be clearly differentiated from other conditions which lead to increase in the levels of prolactin in the blood. This rise in the level of the hormone is normally seen in pregnancy as well as in lactating mothers. Increased physical activity as well as sleep and stress can also account for an increased blood level of the hormone. Certain drugs which include cimetidine, verapamil, opioids and monoamine oxidase inhibitors as well as drugs which antagonize the effects of dopamine can cause high levels of prolactin. In certain other disease conditions also there is a rise in the blood prolactin levels. These pathologies include damage to the spinal cord, insufficiency of thyroid hormone and damage to the liver. Diagnosis is based upon measurement of levels of prolactin, CT scans as well as checking for the other signs and symptoms. The tumor can be treated by invasive procedures, medications or radiotherapy. Surgery is performed to remove the tumor and drugs which include bromocriptine and pergolide are used in the pharmacological treatment. Radiotherapy is performed mostly in cases when even after tumor excision the levels of prolactin do not reduce. Another tumor of the anterior pituitary which is the adenoma of the somatotrophic cells is responsible for an excessive secretion of growth hormone and is referred to as the growth hormone adenoma. This adenoma is next only to the prolactinomas in its incidence. This tumor is mainly diagnosed when it reaches to a considerable size. And most of the tumors arising from the pituitary gland are macroadenomas with cases of microadenomas being as low as 20 percent. These tumors result from a mutation in the gene which encodes the Gs protein. This mutation leads to an increase in the levels of cAMP and it is the most common cause for these adenomas with 40 percent of the diagnosed cases being because of this. This tumor does not present with a greater vulnerability for a particular sex. The main effects that are led to by the increased levels of growth hormone are due to the release of insulin like growth factor from the liver which is also referred to as somatmedian C. This factor is normally also released by the growth hormone but in normal levels which are sufficient enough to produce its effects via its action of producing an increase in the synthesis of DNA, RNA as well as proteins. This tumor presents its manifestations in different ways depending upon the time of its incidence. If the tumor occurs at an early age before the epiphyseal closure in the bones, it can lead to a condition known as gigantism. On the other hand if this condition occurs after the epiphyseal closure within the bones, it is referred to as acromegaly. In gigantism the increased levels of growth hormone are responsible for the lengthening of the long bones and hence the arms as well as legs of these patients elongate. They present with an increase in the size of their body which is also not in proportion. The growth hormone leads to an increase in the blood glucose levels. The pancreas is not able to cope up with the increased load and the cells eventually burn out and many patients with gigantism also suffer from diabetes mellitus. If gigantism is left untreated, it eventually leads to destruction of the pituitary gland itself and results in the reduction of secretion of all hormones of the pituitary gland. On the other hand as acromegaly occurs after the epiphyseal closure of the bones, the patient does not have an increase in length. It results in growth of soft tissues in the body. Some bones whose epiphyses do not fuse on puberty are affected by the growth hormone. The jaw protrudes forward resulting in a condition known as prognathism and the forehead also presents a slanted appearance. The nose also increases in size and the patients can also present kyphosis which develops due to increase in the size of vertebrae. The viscera are also enlarged that is the heart, liver and kidney present with enlargement. Diabetes and dysfunction of the gonads has also been reported with disturbances in the female menstrual cycle. The diagnosis of the condition can be based on various tests. The measurement of the levels of growth hormone should be performed. An important test is the administration of glucose which would normally cause a very low level of growth hormone in the blood. But in patients suffering from the adenomas, the growth hormone levels either do not decrease or even if they do, the decrease is not very significant. The insulin like growth factor levels should also be assessed which would be highly raised in this disease. The radiographs can also be performed and MRI reports assist in the identification of the area of tumor. The surgical removal of the tumor is the best treatment option as it cures the problem in 80 percent of the operated cases. Radiotherapy is also performed but it requires longer duration of time. Medications are also available which include bromocriptine and octreotide acetate. The patients mostly show good response to the treatment and the signs and symptoms of the disease decrease in most of the cases. The hormones of the pituitary gland are very essential for the regulation of bodily functions and a decrease in these hormones can also be harmful. A condition which is referred to as pituitary dwarfism results due to inability of the pituitary gland to secrete growth hormone. This hormone is very important for growth. Every single child is diagnosed with this condition out of 3500 cases in the United States and one within 30000 in the United Kingdom. It occurs at a higher rate in the males than in the females. The disease can be led to by many reasons and the main causative agent is a genetic mutation. The disease presents itself as an autosomal recessive condition. It can also result from damage to the pituitary gland, tumors of the pituitary gland, loss of blood supply to the gland, craniopharyngioma as well as infections of the brain and as a result of radiations. The manifestation of the genetic type of pituitary dwarfism occurs soon after infancy. The growth of the body parts in this pathology is in proportion but the rate of growth is very slow as compared to normal individuals. Thus they have very a very small height and rate of development. The patients do not suffer from mental retardation. The external sex organs in these individuals are not developed properly. The onset of puberty is very late and as there is deficiency of growth hormone there are derangements in the metabolism of glucose with the presentation of decreased blood sugar levels. It is very important to first of all differentiate this condition from the dwarfism which results as a result of reduction in the thyroid hormone levels. The pituitary dwarfs have normal function of the brain whereas the opposite is true for the hypothyroid dwarfs who present with mental retardation. The hypothyroid dwarfs also have disproportionate growth in the body. The diagnosis of the condition requires the measurements of the weight and height of the child and subsequent comparison of the data with the normal age growth chart. As it is important to consider a dwarf to be suffering from hypopituitarism to have proportional growth of the body, it is necessary to take measurements to check for disproportion. The easiest method used to examine this is the arm span technique. The stages of puberty should also be checked and it should be ensured that the delay in puberty is not related to normal familial delay as many people have late onset of puberty because it is a part of their hereditary. The examination of the external sexual organs will assist in determining the development. This is because disturbances in gonadal development are also associated with this condition. Another important test is the administration of growth hormone releasing hormone. If levels of the growth hormone rise after its administration, it is indicative of a defect in the hypothalamus. On the other hand if the levels do not increase, it shows that the defect lies in the pituitary gland and that it is unable to secrete the growth hormone. The best available treatment to cure this condition is the administration of growth hormone. This growth hormone is effective because it is the human growth hormone which is basically genetically engineered and hence it proves to be beneficial. The growth hormone is given in a daily injection. It is helpful as it can lead to reduction of the signs and symptoms related to the condition. References: Top of Form Ganong, W. F. (2005). Review of medical physiology. New York: McGraw-Hill Medical. Top of Form Greenspan, F. S., & Baxter, J. D. (1994). Basic & clinical endocrinology. Norwalk, Conn: Appleton & Lange. Bottom of Form Bottom of Form Top of Form Guyton, A. C., & Hall, J. E. (1996). Textbook of medical physiology. Philadelphia: W.B. Saunders. Kemp S. (2008) Growth Hormone Deificiency. Medscape. http://emedicine.medscape.com/article/923688-overview Bottom of Form Top of Form Kumar, V., Abbas, A. K., Fausto, N., Robbins, S. L., & Cotran, R. S. (2005). Robbins and Cotran pathologic basis of disease. Philadelphia: Elsevier Saunders. Top of Form Mohan, H. (2005). Textbook of pathology. New Delhi: Jaypee Bros. Bottom of Form Bottom of Form Read More