Pituitary Disorders Eiman Ali Basheir Mob: 0915020385 31/1/2019
Objectives By the end of this lecture the students will be able to: Understand basic Pituitary axis physiology State the common causes of hypo and hyper secretion of Pituitary gland Describe the signs and symptoms associated with Pituitary disorders Describe management for Pituitary disorders Discuss anterior and posterior Pituitary disorders
Pituitary Gland- master gland Hypothalamus +
Hypothalmus-a region of brain that controls immense number of bodily functions; located in middle of base of brain, and encapsulates ventral portion of the third ventricle Pituitary gland, also known as hypophysis, a roundish organ that lies immediately beneath hypothalamus, resting in a depression of base of skull called sella turcica ("Turkish saddle"). In an adult human the pituitary is about the size and shape of a garbonzo bean It has three sections, or lobes anterior, intermediate, and posterior
Hypothalamus-functions Hypothalamus- integrative center for endocrine and autonomic nervous system *Hypothalamus and pituitary - integrate communication between nervous and endocrine system Control of some endocrine glands by neural and hormonal pathways Two major groups of hormones secreted: inhibiting and releasing
Hypothalamus Two major groups of hormones secreted: inhibiting releasing
ANTERIOR PITUITARY (Adenohypophysis) SECRETES 6+ HORMONES: ACTH (adrenocorticotropic hormone) controls release of cortisol in adrenal glands *ACTH release; controlled by corticotropin-releasing hormone (CRH)
ANTERIOR PITUITARY(adenohypophysis) TSH (thyroid stimulating hormone) Thyroid releasing hormone; secreted by hypothalamic neurons-control release of TSH GH (growth hormone) (Somatotropin) stimulates growth of bone/tissue
Prolactin- promotes mammary gland growth and milk secretion FSH (follicle stimulating hormone)- stimulates growth of ovarian follicles & spermatogenesis in males LH (lutenizing hormone)- regulates growth of gonads & reproductive activities
Posterior Pituitary (Neurohypophysis) What hormones are released by the posterior pituitary signaled by the hypothalamus? Antidiuretic hormone (ADH) &. Oxytocin
ANTERIOR PITUITARY DISORDERS
ETIOLOGY ANTERIOR PITUITARY HYPERFUNCTION DISORDERS Primary: defect in gland itself -releases a particular hormone that is too much or too little. Secondary: defect is somewhere outside of gland i.e. GHRH from hypothalamus TRH from hypothalamus
10% OF ALL BRAIN TUMORS PITUITARY TUMORS What diagnostic tests diagnose a pituitary tumor? *Determined by symptoms presented; evaluate serum/urine hormone levels; stimulation/suppression tests for hormone levels; CT, MRI, etc Tumors usually cause hyper release of hormones
ANTERIOR PITUITARY HYPERFUNCTION What happens if: TOO MUCH secretion of prolactin (prolactinoma)? Anovulation; menstrual irregularities; galactorrhea TOO MUCH release of Lutenizing Hormone (LH)? Polycystic ovary syndrome;, due to effect on corpus lutea Too much growth hormone secretion? GIGANTISM IN CHILDREN; ACROMEGALY IN ADULTS
Hyperfunction of the Anterior Pituitary- An individual has a tumor of anterior pituitary gland which causes excess ACTH secretion What disease is this? What signs and symptoms are likely to be found? Cushing s disease- condition in which pituitary gland releases too much adrenocorticotropic hormone (ATCH). Cushing's disease- a form of Cushing syndrome Remember this one-see adrenal disorders
MEDICAL INTERVENTIONS PITUITARY TUMOR *Medications (goal...reduce GH levels) Somatostatin analogs (octreotide) GH receptor antagonists (Pegvisomant) Dopamine agonists (cabergoline) Dostinex *inhibits prolactin (prolactinoma)
MEDICAL INTERVENTIONS PITUITARY TUMOR/REPLACEMENT THERAPY Radiation therapy External radiation- bring down GH levels 80% of time Steriotactic radiosurgery-
Neurosurgery: Transsphenoidal hypophysectomy Most commonly used approach Incision thru floor of nose into sella turcica.
Newer Method-EndoscopicTranssphenoidal Hypophysectomy
Posterior Pituitary-(Neurohypophysis) It secrete : ADH (vasopressin) and oxytocin
ADH (Vasopressin) secreted by cells in hypothalmus-stored in posterior pituitary acts on distal & collecting tubules of kidneys making more permeable to H20 volume excreted ADH is released when? With decreases blood volume, increased concentration of Na+ or other substances (drugs as opiooids, thiazide diuretics) also, pain, stress ADH has vasoconstrictive or vasodilation properties? vasocontrictive
Oxytocin Controls lactation & stimulates uterine contractions It is best known for its roles in female reproduction: it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating birth and breastfeeding, respectively. Recent studies have begun to investigate oxytocin's role in various behaviors, including social recognition, bonding, anxiety, trust, and maternal behaviors
Posterior Pituitary Disorders SIADH (Excess ADH): Numerous causes: *Small cell lung cancer, other types cancer CNS disorders *Medications as, thiazide diuretics, opioids, general anesthetics, tricyclic antidepressants, others Miscellaneous
SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion)
If too much ADH, what clinical signs and symptoms are typical? Weight gain urine output serum Na levels (less than120meq/l) weakness muscle cramps H/A
SIADH-if hyponatremia worsens-high risk neuro manifestations lethargy decrease tendon reflexes *seizures-life threatening! (if serum Na less than 120mEq/L)
Posterior Hypopituitary-ADH disorders Diabetes Insipidus-(DI) (too little ADH) Etiology: (50% idiopathic) *Central- neurogenic- i.e. brain tumors Nephrogenic - inability of tubules to respond to ADH Psychogenic-
What Clinical Manifestations-DI? Polydipsia Polyuria (10L in 24 hours) Severe fluid volume deficit weight loss tachycardia constipation shock
Thank You