Pituitary

  • Pituitary Tumor:
  1. It is present in 10% of brain tumours; Erodes the sella and extends into surrounding area.
  2. The most common pituitory tumor is adenoma arising from anterior lobe.
  3. Prolactinomas (Lactotroph Adenomas) are the most frequent type of hyperfunctioning pituitary adenomas.
  4. Earliest method of diagnosing pituitary tumour is CT Scan.
  • Causes of pituitary apoplexy : Preexisting adenoma (spontaneously), Pospartum (sheehan's syndrome), Diabetes mellitus, Hypertension ,Sickle cell anemia, Acute shock.
  • Wermer syndrome(MEN I ) is characterized by Pancreatic neoplasm (insulinoma), Pituitary, and Parathyroid involvement..
  • Association of Parathyroid, Pancreatic and Pituitary tumors along with adrenal cortical hyperplasia and cutaneous angiofibromas suggests a diagnosis of MEN I syndrome.
  • MEN-II:Pancreatitis, pituitary tumor,Medullary Carcinoma of Thyroid and pheochromocytoma
  • A 25 year old female presenting with amenorrhea and galactorrhea is suspected to have malignancy of the pituitary gland. Lateral view of Skull is most useful for visualising the sella turcica.
  • Visual field defect in pituitary tumour with suprasellar extension is Bitemporal Hemianopsia.
  • There are 5 hormones produced by the anterior pituitary. Those hormones are luteinizing hormone (LH), growth hormone (GH), follicle stimulating hormone (FSH), prolactin (PRL) and thyroid stimulating hormone (TSH)..
  • Posterior pituitary secretes Oxytocin and ADH.ADH is formed primarily in supraoptic nuclei, whereas oxytocin is formed mainly in paraventricular nuclei of hypothalamus.
  • Corticotropin releasing factor (CRF) released from the hypothalamic paraventricular nucleus is responsible for release of ACTH from Pituitary.
  • Anterior pituitary has two types of cells : ?
1. Acidophilic cells
  • Somatotrophs → Secrete growth hormone
  • Lactotrophs → Secrete prolactin
2. Basophilic cells
  • Corticotrophs → Secrete ACTH, POMC, MSH
  • Thyrotrophs → Secrete TSH
  • Gonodotrophs → Secrete FSH, LH Posterior pituitary secretes ADH and oxytocin.
  • Polyuria,Galactorrhea,Diabetes Insipidus are caused by accidental transection of pituitary stalk.
  • Insulin is a pancreatic hormone, not under the control of pituitary. Transection of the pituitary stalk would therefore in no way affect glucose levels or lead to diabetes mellitus.
  • A 7 yr old boy underwent neurosurgery for craniopharyngioma following which pituitary functions were lost. Hydrocortison hormone should be replaced first.
  • Most pituitary tumors are approached through the nose by the trans-sphenoidal approach.
  • Secondary Amenorrhea and galactorrhea in a young women with evidence of microadenoma in the pituitary fossa suggest a diagnosis of prolactinoma.
  • Oral dopamine agonists (Dopamine or Cabergoline) are the treatment of choice for patients with prolactinomas.
  • Adenohypophysis(anterior lobe) develops from an upward growth (Rathke's pouch) from the ectodermal roof of stomodeum. 
  • Neurohypophysis (posterior lobe) develops from a downgrowth from the 3rd ventricle/diencephalon (neuroectoderm) called infundibulum.
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