Diseases of the Anterior Pituitary Gland PDF

Page 1 Saturday, September 21, 2024 8:10 PM Diseases of the Anterior Pituitary Gland - Hypersecretion ○ General information ▪ The master gland of the pituitary is the hypothalamus ▪ Anterior pituitary = adenohypophysis...

Page 1 Saturday, September 21, 2024 8:10 PM Diseases of the Anterior Pituitary Gland - Hypersecretion ○ General information ▪ The master gland of the pituitary is the hypothalamus ▪ Anterior pituitary = adenohypophysis ▪ Posterior pituitary = neurohypophysis ▪ Most hypersecretions of the anterior pituitary are due to adenomas □ Microadenomas < 10mm in size Most are functional adenomas ◊ Functional means they cause secretion of excess hormones □ Macroadenomas > 10mm in size Most are non-functional adenomas ◊ Non-functional means they do not secrete hormones, and instead cause compression of the surrounding tissues due to their size □ Treatment is to remove the adenoma and undergo hormone replacement as necessary ○ Hyperprolactinemia ▪ This is the most common type of functional adenoma of the anterior pituitary ▪ Gender differences □ Females This disease manifests most commonly as a microadenoma Clinical presentation ◊ Galactorrhea, amenorrhea, infertility □ Males This disease manifests most commonly as a macroadenoma Clinical presentation ◊ Decreased libido, impotency, sterility, gynecomastia ▪ Hormones □ Prolactin Produces milk and suppresses FSH & LH □ Oxytocin Secretes milk □ FSH Females ◊ Prepares uterus to receive mature egg ◊ Matures the ovum in the ovary ◊ Stimulates estrogen Males ◊ Production of sperm □ LH Females ◊ Release mature egg ◊ Produce progesterone Males ◊ Stimulates interstitial cells of Leydig to produce testosterone Exam 1 Page 1  ◊ Stimulates interstitial cells of Leydig to produce testosterone  Aka interstitial cell secretion hormone ▪ Treatment □ Prescribe bromocriptine which gives a dopamine-like effect Dopamine is a prolactin inhibitory hormone ○ Excessive Growth Hormone ▪ Decreased GHRH; increased somatotropin ▪ This is the 2nd most common pituitary adenoma ▪ Most common cause of death is heart disease ▪ Gigantism □ Excessive growth hormone present before the epiphyses of the bones have fused □ Person is taller than expected; bones grow in length and width □ Signs/ symptoms Organomegaly, normally the heart Hands are spade and sausage-like ▪ Acromegaly □ Excessive growth hormone present after the epiphyses of the bones have fused □ Bones grow only in width □ Signs/ symptoms Cardiomegaly, which is secondary to hypertension Prognathism ○ Cushing Disease ▪ Decreased CRH; increased ACTH & cortisol ▪ Most often caused by pituitary adenoma ▪ More common in males; Male to female is 10:1 ▪ Signs/ symptoms □ Produces bilateral adrenal hyperplasia if adenoma is in the adrenal glands □ Can cause a slight elevated MSH effect - Hyposecretion ○ Simmonds's disease ▪ Effects of this disease is panhypopituitarism (pan means global, so decrease in all pituitary hormones) ▪ Causes of Simmonds's disease: □ Sheehan's syndrome Described as post-partum pituitary necrosis □ Non-functional pituitary tumor compressing normal tissue □ Pituitary failure in late acromegaly □ Hypophysectomy □ Infiltrative disease like Hand-Schuller-Christian disease ○ Pituitary dwarfism ▪ Described as a congenital disease that is isolated growth hormone deficiency ▪ Can be treated with growth hormone injections during puberty Diseases of the Posterior Pituitary Gland - Excessive ADH secretion ○ SIADH ▪ Causes □ CNS diseases □ Ectopic production Pulmonary diseases like tuberculosis Malignant tumors like small cell carcinomas of the lung (SCLC) □ Drugs ▪ Effects Exam 1 Page 2  ▪ Effects □ Excessive water retention □ Hyponatremia - Insufficient ADH secretion ○ Diabetes insipidus ▪ Causes □ Idiopathic; head injuries, tumors, infections ▪ Effects □ Polyuria, excessive thirst, and polydipsia □ Does NOT cause polyphagia (increased hunger) Diseases of the Thyroid Gland - Goiter ○ May be diffuse (smooth) or focal (nodes/ lumps) ○ Can compress the trachea, esophagus, or recurrent laryngeal nerve - Hyperthyroidism ○ Grave's disease ▪ Decreased TRH and TSH, increased T3/T4 ▪ Etiology □ Type II hypersensitivity autoimmune disease □ Presence of IgG antibodies that stimulate the thyroid gland IgG can cross the placenta, so a pregnant woman with Grave's can affect the baby ▪ More common in females; female to male is 7:1-10:1 ▪ Features □ Increased BMR, sweating, heat intolerance, weight loss □ Exophthalmos, tachycardia, hypertension, dyspnea □ Lid lag where a person follows a finger down and the eyelids don’t follow ○ Granulomatous thyroiditis aka De Quervian thyroiditis ▪ Can have a viral origin like EBV ▪ Infection can cause thyroid gland to swell, leading to transient hyperthyroidism ▪ Condition gets better over time and resolves on its own - Hypothyroidism ○ Cretinism ▪ Classified as hypothyroidism in childhood ▪ Causes □ Iodine deficiency, goiter in mother during pregnancy, and congenital enzyme deficiency ▪ Effects □ Delayed development, large protruded tongue, umbilical hernia ○ Myxedema ▪ Classified as hypothyroidism in adulthood ▪ Most common cause is Hashimoto's ○ Hashimoto's Thyroiditis ▪ Aka chronic lymphocytic thyroiditis ▪ Decreased T3/T4, increased TRH and TSH ▪ Etiology □ Type IV hypersensitivity autoimmune disease □ Presence of destroyed cytotoxic T cells ▪ More common in females; female to male is 10:1 ▪ Features □ Decreased BMR, cold intolerance, weight gain □ Bradycardia, hypotension, hypoventilation □ Depression is a classic symptom that is overlooked Riedel thyroiditis Exam 1 Page 3  ○ Riedel thyroiditis ▪ Classified as chronic non-caseous granulomas ▪ Causes fibrosis of the thyroid gland, leading to a "Woody thyroid" - Thyroid neoplasms ○ Follicular adenoma ▪ Classified as a benign tumor ▪ It is the most common neoplasm of the thyroid gland ▪ More common in females; female to male is 7:1 ▪ Presents with "cold" nodules that do not take up iodine ○ Thyroid carcinoma ▪ Classified as malignant tumors, and generally uncommon overall ▪ Types □ Papillary carcinomas aka adenocarcinoma It is the most common of all thyroid carcinomas More common in females; female to male is 3:1 Generally slow growing with positive lymph nodes at time of diagnosis Presents with psammoma bodies, which are laminated calcium deposits It is of follicular epithelial cell origin and has a thyroglobulin tumor marker □ Follicular carcinomas It is the second most common of thyroid carcinomas It is of follicular epithelial cell origin and has a thyroglobulin tumor marker □ Anaplastic carcinoma More common in females over the age of 50 It is a rapid growing tumor that metastasizes locally through lymph and blood □ Medullary carcinoma Generally slow growing that is infiltrative but doesn’t produce metastases It is of parafollicular or C cells origin The tumor produces calcitonin Exam 1 Page 4