Pituitary Flashcards
What are the 9 endocrine glands?
Hypothalamus Pituitary Thyroid Parathyroid Adrenals Pancreas Ovaries Testes Pineal Gland
What do the endocrine glands produce?
Hormones
In general, what do hormones do?
Are secreted into the blood where they affect body tissues or organs (target tissues)
Where do hormones bind?
To specific cell receptors either in the cell membrane or inside the cell
What are the two types of hormones?
Lipid-soluble
Steroids, thyroid hormones (inactive when bound – must be bound to protein to be transported INTO the cell)
Water-soluble
Protein-based (always active)– attach to cell membrane receptors
They are a 1st messenger that stimulate a 2nd messenger!
What is the most common hormone feedback system?
Negative feedback (Low Ca+ levels stimulate PTH to increase Ca+ levels which then inhibits further PTH)
What is complex feedback?
When one hormone tells another hormone to act [TRH stimulates TSH; when TSH levels are sufficient – T3 & T4 tell TRH (hypothalamus) & TSH (anterior pituitary) to stop.]
How does the nervous system regulate stress?
Tells the adrenal medulla to give up some catecholamines (epinephrine & norepinephrine) to increase HR & BP to better deal with the stress.
What two types of hormone groups are secreted by the hypothalamus?
Releasing hormones
Inhibiting hormones
What are the releasing hormones?
Corticotropin–releasing hormone (CRH) Thyrotropin-releasing hormone (TRH) Growth Hormone releasing factor Gonadotropin-releasing hormone (GnRH) Prolactin-Releasing hormone
What are the inhibiting hormones?
Somatostatin
Prolactin-inhibiting hormone
What is the “Master” Gland?
Pituitary
How many lobes does the pituitary have?
Anterior lobe (80% of gland) Secretes 6 hormones (stimulated by the hypothalamus releasing hormones) CRH -> ACTH TRH -> TSH GH-Releasing factor -> GH Gonadotropic -> LH & FSH MSH -> melanocytes Prolactin releasing hormone -> prolactin Posterior lobe Secretes 2 hormones (made by hypothalamus but stored here) Oxytocin ADH
What are some things that stimulate ADH?
Increased plasma osmolality Decreased fluid volume Hypotension Pain N/V
What are some things that inhibit ADH?
Decreased plasma osmolality
Increased fluid volume
B-adrenergic agonists
Alcohol
What are the 3 problems that can occur in the anterior pituitary?
Hyperpituitarism
Hypopituitarism
Compression of cerebral tissue
What is the most common cause of pituitary problems?
Benign tumor (adenoma)
What are the anterior and posterior pituitary disorders?
Anterior - Hyperpituitarism (GH excess, acromegaly/gigantism - Hypopituitarism Posterior - Hyper = SIADH - Hypo = DI
What is the most common cause of hyperpituitarism?
Excess secretion of growth hormone & prolactin
What most often causes excess GH and prolactin?
Pituitary tumor
What does this GH and prolactin cause in the adult & why?
Acromegaly – epiphyseal plate is closed so bones can’t get longer; instead have thickened bones & tissues
What does this cause in children & why?
Gigantism – epiphyseal plate is still open so long bone growth occurs
What are the hallmark manifestations of acromegaly?
Enlargement of hands/feet
Mandible enlargement
Coarsening of facial features
Joint pain & deformity
What tests are used in the diagnosis of acromegaly?
IGF-1 levels (more reliable than GH levels)
OGTT (b/c GH is inhibited by glucose)
What is the treatment of choice for reducing GH levels & may cure hyperpituitarism?
Tumor removal = Transsphenoidal hypophysectomy
Total gland removal -> need for lifelong hormone replacement (glucocorticoids, thyroid hormone, sex hormones) -> NEED to monitor for hormone insufficiency
May lose FSH & LH -> infertility – assist with grief process
What does the patient need teaching on pre-op transsphenoidal hypophysectomy?
Avoid teeth brushing 10 days
Will need oral care Q 4 hours
Avoid coughing , sneezing, straining
NO bending for 2 months!
What will the nurse need to do post-op transsphenoidal hypophysectomy?
HOB > 30 (decreases HA which is common)
Monitor neuro status
Monitor for DI (urine output, serum/urine osmolality)
Occurs b/c ADH is stored in posterior lobe or cerebral edema due to manipulation of pituitary
What will be in place when pt returns from surgery?
Nasal packing
What should you do if the pt starts having clear nasal drainage?
Send to lab to test for glucose
What does a glucose > 30 indicate?
CSF leakage
What complaints may mean CSF leakage?
Severe headache
How long do leaks take to resolve?
Within 72 hours
If a CSF leak occurs, what does the pt need & why?
IV Antibiotics to prevent meningitis
If surgery fails or pt isn’t a candidate, what will the pt with hyperpituitarism need? (Note: may also be done to shrink a tumor prior to sx)
Radiation therapy
How long can radiation therapy assist with reducing GH levels?
Up to 2 years
What can radiation therapy cause?
Hypopituitarism (requiring HRT)
What is the most common drug used to tx acromegaly?
Octreotide (Sandostatin) – reduces GH levels.
How is octreotide given?
Subcutaneously 3x/week
What is another drug alternative?
Pegvisomant (Somavert) – blocks action of GH
Which pituitary lobe is affected by hypopituitarism?
Anterior lobe
What is the cause of hypopituitarism?
A decrease in one or more of the pituitary hormones
What hormones are secreted by the anterior pituitary gland?
ACTH, TSH, FSH, LH, GH, prolactin (gonadotropins & GH are most common deficiencies)
What is a deficiency of one of these anterior pituitary hormones called?
Selective hypopituitarism
What is a total failure of the pituitary gland called?
Panyhypopituitarism (b/c ALL hormones are deficient)