Keeping in mind the global need of medical knowledge, sqadia.com follows medical books that are accepted throughout the entire world, so that every medical student can get advantage of the medical lectures made by sqadia.com. The lecture pituitary gland is also designed by following the instructions of the book of Pathology i.e. ¨Rubin’s Pathology¨. This lecture explains the abnormalities associated with the hormones. Dr. Ammar-Ul-Hassan explains that how the condition hypopituitarism arises, how mutation in genes leads to inherited isolated growth hormone deficiency. Also, pituitary adenomas, central and nephrogenic diabetes insipidus are discussed respectively.
For MBBS students, detailed explanation of hypopituitarism is delivered under the lecture title pituitary gland. The hormones released by anterior pituitary are FSH and LH, GH, TSH, prolactin, and ACTH. The condition in which pituitary gland do not release enough amount of one of these hormones is referred to as hypopituitarism. However, this is a rare condition. Associated causes of hypopituitarism are pituitary tumors, Sheehan syndrome, pituitary apoplexy, infiltrative diseases, empty Sella syndrome. Pituitary tumors are responsible for half of hypopituitarism. In Sheehan syndrome, ischemic necrosis of pituitary results in panhypopituitarism. Pituitary apoplexy is a condition associated with inactive adenomas and lead to hypopituitarism. There is a radiation damage to hypothalamic-pituitary-adrenal axis (HPA) in Iatrogenic Hypopituitarism.
Growth Hormone Abnormalities
Inherited isolated growth hormone deficiency is differentiated into 3 types i.e. type IA, type IB, type II, and type III on the basis of mutations caused in different genes. Mutations targeting transcription factors affect a variety of genes, some of which are Pit-1 gene, in which mutations cause combined pituitary hormone deficiency (CPHD), PROP1 (5q) gene, in which mutations inactivate LH, FSH, GH, PRL, and TSH. Growth hormone insensitivity, also known as Laron syndrome or Laron dwarfism, is a disorder characterized by short stature due to extreme resistance to GH because of abnormalities in growth hormone receptor (GHR). A hormonal disorder that results from too much growth hormone (GH) in the body is known as acromegaly. Special testing for growth hormone includes GH deficiency, which is a provocative test, and GH excess, which is an oral glucose tolerance test (OGTT).
Pituitary adenomas are benign tumors that often cause excess secretion of one or more pituitary hormones and corresponding endocrine hyperfunction. Etiological factor involved in causing pituitary adenomas are hormonal, environmental, and genetic factors. Acquired activating mutations in stimulatory subunit of Gs protein are associated with GH-secreting adenomas. Clinical feature of pituitary adenomas follows severe headaches, loss of central vision, oculomotor palsies, hyperphagia, and hormonal syndromes. Hyperprolactinemia is the most common endocrinopathy and occurs In lateral or posterior parts of gland. Pathologically, lactotroph adenomas are chromophobic. Some of the features of hyperprolactinemia are amenorrhea, galactorrhoea, decreased libido and impotence (men). For the treatment of hyperprolactinemia, dopamine agonists and inhibition of PRL secretion is used to cure microadenomas. However, surgery and radiation therapy is followed for macroadenomas.
Types of Pituitary Adenomas
Types of Pituitary Adenomas are enlightened in the medical lecture made by sqadia.com for the ease of medical students by following the medical book ¨Rubin’s Pathology¨. Somatotroph adenomas occurs due to excess GH secretion. They can cause gigantism or acromegaly. Pathologically, densely granulated adenomas are acidophilic cells with granular cytoplasm and diffuse growth pattern. Sparsely granulated adenomas are small chromophobe cells. Treatment can be carried out through transsphenoidal hypophysectomy, radiation therapy, or long-acting analog of somatostatin. Corticotrope adenomas are intrasellar microadenomas. Gonadotroph adenomas are mainly hormonally inactive adenomas and grow in diffuse pattern. Thyrotrope adenomas can be invasive and fibrotic. Nonfunctional pituitary adenomas do not cause endocrinopathies.
Posterior Pituitary Disorders
Posterior pituitary disorders are discussed comprehensively in the medical video lecture at the platform of sqadia.com for medical and MBBS students. Central diabetes insipidus is a lack of the hormone vasopressin that causes excessive production of very dilute urine. Central diabetes insipidus has several causes, including a brain tumor, a brain injury, brain surgery, tuberculosis, and some forms of other diseases. Nephrogenic diabetes insipidus is caused by problems related to a hormone called antidiuretic hormone or ADH. In this condition, the hormone is produced normally but kidneys are unable to sense its production. Craniopharyngiomas are caused due to central diabetes insipidus, and trauma and hypophysectomy. There is a localized hemorrhage or infarction.