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)
What is the usual cause of hormone deficiency resulting in hypopituitarism?
Pituitary Tumor
What are the common symptoms of pituitary tumor?
HA
Visual changes (decreased peripheral vision, decreased acuity)
Anosmia (loss of smell)
Seizures
What is the treatment for hypopituitarism?
Sx or Irradiation (tumor removal) -> lifelong HRT
What is the usual HRT for GH deficiency?
Somatropin (Omnitrope, Genotropin, Humatrope)
What would you expect to see with GH HRT?
Increased energy
Increased lean body mass
Feeling of well-being
Improved body image
How is Somatropin given?
Daily subcutaneous (preferably in the evening)
How is Somatropin dosing adjusted?
Relief of symptoms
IGF-1 levels
Development of adverse effects
In pts with gonadotropin deficiency, which pts should not receive HRT?
Breast CA, Phlebitis, PE (in women) Prostate CA (in men)
What hormones does the posterior pituitary store and release?
ADH & Oxytocin
What gland produces these hormones?
Hypothalamus
What syndrome occurs with the overproduction of ADH?
SIADH
What syndrome occurs with the underproduction of ADH?
DI
If the pituitary quits functioning, will the hormones still be produced?
Yes (because the hypothalamus is still working)
What does ADH do?
Regulates water balance and osmolarity (regulates renal retention & excretion of water)
What is another name for ADH?
Vasopressin
What happens in SIADH?
There is more ADH then normal -> decreased urine output & fluid retention
What happens in DI?
There is not enough ADH -> increased urine output & dehydration
Which of the posterior pituitary disorders is a common cause of dilutional hyponatremia?
SIADH
If the patient is retaining urine, what will the urine produced look like?
Concentrated
What is the most common cause of SIADH?
Malignancy
So if no other reason can be found for SIADH, what should the pt be evaluated for?
Presence of cancer (CA)
If SIADH is caused by head trauma or drug-induced, it is usually
self-limiting
If SIADH is caused by malignancy, it is usually
chronic
What are the early signs of hyponatremia?
Thirst
Exertional dyspnea Fatigue
What are the late signs of hyponatremia
Muscle cramping
Pain
Weakness
So if the body is retaining urine, what will happen with the body weight?
Increase
If sodium continues to fall (< 120 mEq/L) what may occur?
N/V, abd cramps, muscle twitching, seizures
Cerebral edema à lethargy, confusion, HA, coma
How is SIADH diagnosed?
Simultaneous measurement of urine and serum osmolality
Na < 135 mEq/L
Serum osmolality < 280 mOsm/kg
Urine specific gravity > 1.005 (concentrated!)
Will have decreased BUN, Cr, H & H (hemodiluted!)
How is SIADH treated?
Treat the underlying cause! (If it’s a tumor, remove or irradiate it!)
Which medications stimulate ADH release & should be avoided in these pts?
Oxytocin Carbamazepine (Tegretol) Chlorpromadmide (Diabinese) Anesthetics & Opioids Thiazides SSRI & Tricyclic antidepressants Antineoplastic agents
What is the immediate treatment goal of SIADH?
Restore fluid volume and osmolality
Mild to moderate (> 125 mEq/L) = Fluid restriction 800-1000 mL/day; Possibly loop diuretic
Severe (< 125 mEq/L) = IV hypertonic saline (3-5%) on (SLOW) infusion pump w/ Fluid restriction 500 mL/day
If you give the pt Lasix (furosemide), what might they need supplements of?
Potassium, Calcium, Mg – (due to increases losses!)(With meals!)
If the pt has chronic SIADH, what is the recommended tx?
800-1000 mL/day; If not tolerated, give demeclocycline (Declomycin) – blocks affects of ADH on renal tubules (Must be given in monitored setting to avoid increasing Na+ too rapidly!)
What should the pt with chronic SIADH be taught?
Increase K+ in the diet
Weigh daily & report any sudden changes
What should the nurse be assessing for in SIADH?
Hourly: Vital signs, urine output, urine spec gravity
Routine: Neuro status, electrolyte lab values
Daily: Weight
If the pt is on fluid restriction, what care does the pt need?
Frequent mouth rinses / oral care
If pt has chronic SIADH, what should you teach them?
Fluid restrict of 800-1000ml/day
Use ice chips or sugarless gum to decrease thirst
S/S electrolyte imbalances (esp Na & K)
What disorder is caused by a deficiency in or a decrease in renal response to ADH?
Diabetes Insipidus (DI)
What is the main result of DI?
Increased urine output & increased plasma osmolality (Dilute urine! – and lots of it [up to 20 L/day])
There are several classifications of DI. Which one occurs due to a lesion of the hypothalamus, infundibular stem, or posterior pituitary, or head trauma, or sx?
(It is the most COMMON form & is secondary b/c something else has caused it!) Central DI (Neurogenic DI)
What type of DI occurs when there is adequate ADH but decreased response to it by the kidney?
NEPHROgenic DI
What are the most common causes of nephrogenic DI?
Lithium, Hypokalemia, Hypercalcemia
What type of DI occurs due to excessive water intake?
Primary DI (also called psychogenic)
What are the two main characteristics of DI?
Polyuria & Polydipsia
What would you expect to see with the urine?
Specific gravity < 1.005 (diluted!)
Decreased urine osmolality
The patient with DI, will have what electrolyte imbalance?
Hypernatremia
What would you expect serum osmolality to be?
Increased (> 295 mOsm/kg)
What will happen if fluid intake is low & the pt is urinating massive amts of urine?
Severe FVD
What s/s would you expect to see?
Weight loss, constipation, decreased skin turgor, hypotension, tachycardia -> CNS irritability, decreased LOC -> shock -> coma -> eventual vascular collapse
What is the initial step in treating DI?
Figuring out the cause to ID which type it is
Which type of DI is due to overhydration & hypovolemia? (NOTE: The other two are due to underhydration & hypovolemia)
Primary (psychogenic) DI
What test is given to confirm central (neurogenic) DI?
Water deprivation test
How does this test rule out nephrogenic DI?
Because ADH is given & will not restore urine osmolality such as it will in central DI
What baselines must be obtained prior to a water deprivation test?
Weight, pulse, urine & plasma osmolality, urine specific gravity, BP
What should the pt be instructed about prior to the water deprivation test?
No fluid intake 8-16 hours prior to the test
What will you assess hourly during the water deprivation test?
BP, weight, urine osmolality
How long does the water deprivation test continue?
Until urine osmolality stabilizes (hourly increase < 30 mOsm/kg in 3 consecutive hours OR weight declines by 3% OR orthostatic hypotension occurs)
Once osmolaltiy is stable, what is given to the pt?
Vasopressin (ADH) – urine osmolality checked 1 hour later
What is the tx for nephrogenic DI?
Low-sodium diet (helps decrease u/o) Thiazide diuretics (reduces flow to ADH-sensitive distal nephrons) IF the 1st two are ineffective à Indomethacin (Indocin) given (increases renal response to ADH)
What is the hormone replacement of choice for central (neurogenic) DI?
Desmopressin acetate (DDAVP)
What other meds may be used to tx central DI?
Pitressin (vasopressin)
chlorpropamide (Diabinese)
carbamazepine (Tegretol)
When giving DDAVP, what do you need to assess?
Response – any wgt gain, HA, restlessness, s/s hyponatremia, water intoxication
Intake & Output, urine specific gravity
Why do you need to monitor the urine specific gravity with DDAVP?
If pt develops increased u/o with low specific gravity call physician immediately (indicates need for increased dosing of DDAVP)
What nursing mgt is needed for DI?
Strict I & O
Keep cold fluids of pts liking at bedside; offer frequently
Monitor electrolytes closely; replace PRN
Daily wgt
S/S FVD (tachycardia, weak thready pulse, hypotension, etc)
Titrate IVF to urine output
Hypotonic saline or
D5W (if used, monitor glucose levels!)
What can hyperglycemia & glucosuria lead to?
Osmotic diuresis -> increasing FVD
Why is the pt with DI at risk for disturbed sleep pattern?
Nocturia
