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N935 Advanced Pathophysiology II > Endocrine Pituitary Gland > Flashcards

Endocrine Pituitary Gland Flashcards

1
Q

endocrine gland

A

secretes hormone directly into the surrounding ECF

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2
Q

exocrine gland

A

products discharged through ducts

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3
Q

important endocrine glands (7)

A
  • pituitary gland
  • thyroid gland
  • parathyroid glands
  • pancreas
  • adrenal glands
  • ovaries and testes
  • placenta
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4
Q

hormones

A
  • mediators of the endocrine system
  • chemical messengers that transport information (a message) from one set of cells (endocrine cells) to another (target cells)
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5
Q

what is the primary event that initiates a response to the hormone?

A

binding to a target cell receptor

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6
Q

hormone receptor

A
  • high specificity and affinity for the correct hormone

- location of the receptor directs the hormone to the correct target organ or target cell

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7
Q

neural control of hormone secretion

A
  • can suppress or stimulate hormone secretion
  • stimuli include pain, smell, touch, stress, sight, and taste
  • hormones under neural control include catecholamines, ADH, cortisol
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8
Q

biorhytm control of hormone secretion

A
  • genetically encoded or acquired biorhythms
  • intrinsic hormonal oscillations may be circadian, weekly, or seasonal
  • may vary with stages of life
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9
Q

feedback mechanism control of hormone secretion

A
  • negative feedback loop

- positive feedback loop

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10
Q

pituitary gland function

A
  • collects and integrates information from almost everywhere in the body
  • uses information to control secretion of pituitary hormones
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11
Q

pituitary gland hormone secretion regulation

A

-regulated by feedback control from peripheral target organ hormones or other target products

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12
Q

do the pituitary and hypothalamus have a BBB?

A

no!! allows feedback products to have a potent effect on them

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13
Q

location of pituitary gland

A

sella turcica at base of brain

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14
Q

two portions of pituitary gland

A
  • anterior lobe (adenohypophysis)

- posterior lobe (neurohypophysis)

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15
Q

what provides blood supply to the pituitary gland?

A

superior and inferior hypophyseal arteries

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16
Q

6 hormones secreted by anterior pituitary

A
  • growth hormone (somatostatin) (GH)
  • adrenocorticotropic hormone (ACTH)
  • thyroid stimulating hormone (TSH)
  • follicle stimulating hormone (FSH)
  • luteinizing hormone (LH)
  • prolactin
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17
Q

thyroid hypothalamic and anterior pituitary hormone system

A
  • hypothalamic hormone = thyrotropin releasing hormone
  • ant pit target cell = thyrotroph
  • ant pit hormone = TSH
  • hormone target site = thyroid gland
  • primary feedback hormone = triiodothyronine (T3)
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18
Q

cortisol hypothalamic and anterior pituitary hormone system

A
  • hypothalamic hormone = corticotropin releasing hormone
  • ant pit target cell = corticotroph
  • ant pit hormone = ACTH
  • hormone target site = zona fasciculata and zona reticularis of adrenal cortex
  • primary feedback hormone = cortisol
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19
Q

gonad hypothalamic and anterior pituitary hormone system

A
  • hypothalamic hormone = gonadotropin releasing hormone
  • ant pit target cell = gonadotroph
  • ant pit hormone = FSH, LH
  • hormone target site = gonads (ovaries, testes)
  • primary feedback hormone = estrogen, progesterone, testosterone
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20
Q

pituitary disorders classification

A
  • primary disorder = defect to the peripheral endocrine gland
  • secondary disorder = defect to pituitary
  • tertiary disorder = defect to the hypothalamus
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21
Q

panhypopituitarism

A

generalized pituitary hypofunction

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22
Q

causes of panhypopituitarism

A
  • nonfunctioning tumors compress/destroy normal pituitary tissue
  • hypophysectomy
  • postpartum shock
  • irradiation
  • trauma
  • infiltrative disorders (sarcoidosis)
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23
Q

treatment of panhypopituitarism

A
  • surgical removal of the tumor or the pituitary gland
  • decompress or remove tumor
  • may require hormone replacement post op (TH, glucocorticoids, vasopressin)
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24
Q

anterior pituitary hypersecretion

A

-usually caused by benign adenomas

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25
Q

three most common tumors that cause anterior pit hypersecretion

A
  • prolactin = amenorrhea, infertility, decreased libido, impotence
  • ACTH = cushings
  • GH = promotes growth of ALL tissues capable of growing
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26
Q

When does GH secretion increase

A
  • stress
  • hypoglycemia
  • exercise
  • deep sleep
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27
Q

what is a major target of GH?

A
  • liver

- GH stimulates production of insulin-like growth factor type 1 (IGF-1) which mediates many of the effects of GH

28
Q

what other tissues/organs grow because of GH?

A
  • skeletal muscle
  • heart
  • skin
  • other visceral organs
29
Q

GH Hypersecretion

A
  • usually caused by GH secreting pituitary adenoma
  • adults = acromegaly
  • children before puberty = gigantism
30
Q

acromegaly

A

sustained hypersecretion of GH after adolescence

31
Q

gigantism

A

hypersecretion of GH prior to puberty, before closure of growth plates
may reach 8 to 9 feet tall

32
Q

common features of acromegaly

A
  • skeletal overgrowth (overgrowth of mandible)
  • soft tissue overgrowth (narrow glottic opening, large tongue)
  • visceromegaly
  • osteoarthritis
  • glucose intolerance
  • skeletal muscle weakness
  • extrasellar tumor extension
  • peripheral neuropathy
33
Q

comorbidities associated with acromegaly

A
  • HTN
  • cardiomyopathy
  • ischemic heart disease
  • DM
  • osteoarthritis
  • skeletal muscle weakness/fatigue
  • increased lung volumes
  • sleep apnea (due to airway changes)
  • increased size of liver, spleen, kidneys and heart
34
Q

treatment of acromegaly

A
  • restore normal GH levels
  • microsurgical removal of tumor with preservation of the gland (preferred)
  • small tumor = transsphenoidal approach
  • large tumor = intracranial
  • irradiation and/or suppressant drug therapy are adjunctive treatments for non surgical conditions
35
Q

airway considerations for acromegaly

A
  • airway changes = large tongue, lips and epiglottis, overgrowth of mandible, vocal cord dysfunction and enlarged tongue, epiglottis and nasal turbinates
  • upper airway obstruction
  • difficult mask
  • impaired visualization of cords
  • subglottic narrowing
  • dyspnea/hoarseness (larynx involved)
  • subglottic stenosis common (may need smaller tube)
36
Q

other anesthetic considerations for acromegaly

A
  • many have sleep apnea
  • patients often have postop respiratory obstruction or failure
  • may have HTN, ischemic heart disease, and arrhythmias
  • skeletal muscle weakness
  • hyperglycemia (monitor BG carefully)
  • may have thyroid axis impairment too –> may need stress steroids and thyroid replacement
  • entrapment neuropathies common
37
Q

preop prep for pituitary surgery

A
  • thorough history and physical
  • labs = glucose, lytes, hormone levels
  • imaging to determine extent of tumor invasion
  • EKG - signs of LV hypertrophy and arrhythmias
  • consider ECHO if cardiac dysfunction present
  • optimize CV function before surgery
  • allen test before a line insertion
38
Q

anesthetic considerations for transsphenoidal approach

A
  • HOB elevated 15 degrees
  • art line for BP monitoring
  • lumbar drain may be placed
  • consider monitoring for VAE
  • usually not significant blood loss
  • submucosal injection of EPI or topical vasoconstrictors may result in HTN
  • anesthetic technique chosen should allow for muscle relaxation, smooth extubation, and rapid neuro assessment
  • hypotension may be due to inadequate cortisol - replace with hydrocort 50-100 mg IV
39
Q

complications of transsphenoidal approach

A
  • CN damage
  • epistaxis
  • hyponatremia
  • CSF leaks
  • DI
40
Q

Diabetes insipidus (DI)

A
  • can occur intra or post op because of surgical trauma to post pit (trauma is reversible)
  • results in insufficient ADH
  • diagnosis made by measuring serum lytes, plasma osm, urine osm
  • treatment = monitor UOP and lytes; DDAVP, restrict sodium intake
41
Q

posterior pituitary hormones

A
  • ADH (arginine vasopressin)

- oxytocin

42
Q

ADH

A

controls renal water excretion and reabsorption

major regulator of serum osmolarity

43
Q

oxytocin

A

stimulates uterine contractions, stimulates myoepithelia cells of breast for milk ejection during lactation, used for inducing labor and decreasing postpartum bleeding

44
Q

three types of vasopressin receptors

A
  • V1 - vasoconstriction
  • V2 - water reabsorption in renal collecting ducts
  • V3 - found in CNS and stimulates modulation of corticotrophin secretion
45
Q

posterior pit stimuli for ADH release

A
  • increased plasma sodium
  • increased serum osm
  • decreased blood volume
  • smoking (nicotine)
  • pain
  • stress
  • nausea
  • vasovagal reaction
  • ang II
  • PPV
46
Q

types of DI

A
  • neurogenic or central = caused by inadequate release of ADH
  • nephrogenic = renal tubular resistance to ADH
47
Q

causes of neurogenic DI

A
  • head trauma
  • brain tumor
  • neurosurgery
  • infiltrating pituitary lesions
48
Q

what can nephrogenic DI be associated with

A
  • hypokalemia
  • hyperkalemia
  • genetic mutations
  • hypercalcemia
  • medication induced nephrotoxicity
49
Q

inhibitors of ADH action or release

A
  • ethanol
  • demeclocycline
  • phenytoin
  • chlorpromazine
  • lithium
50
Q

ADH deficiency symptoms

A
  • polyuria (hallmark sign)
  • inability to produce concentrated urine
  • dehydration
  • hypernatremia
  • low urine osm (<300 mOsm/L)
  • urine spec gravity < 1.010
  • urine vol > 2 mL/kg/hr
  • serum osm > 290 mOsm/L
  • sodium > 145 mEq/L
  • neuro symptoms = hyperreflexia, weakness, lethargy, seizures, coma
51
Q

medical treatment for mild or incomplete DI

A
  • meds that augment the release of ADH or increase receptor sensitivity
  • chloropropamide
  • carbamazepine
  • clofibrate
52
Q

medical treatment for significant DI

A

-ADH preparations like DDAVP

53
Q

DDAVP

A
  • selective V2 agonist
  • DOA = 8-12 hours
  • less vasopressor activity
  • enhanced antidiuretic properties
  • admin - oral, subQ, IV
54
Q

posterior pituitary pre op assessment considerations

A
  • careful assessment of plasma lytes, renal function, and plasma osm
  • dehydration = sensitive to hypotensive effects of anesthetics
  • intravascular volume replacement (24-48 hours before) with isotonic fluids
55
Q

preop treatment of incomplete DI

A

-DDAVP treatment not necessary because surgical stress stimulates ADH secretion

56
Q

preop treatment of complete DI

A
  • DDAVP (1-2 mcg IV or subQ)
  • aqueous vasopressin (5-10 units IM or SubQ)
  • caution needed for patients with CAD (because of hypertension caused by ADH)
57
Q

what do you do if the plasma osm rises above 290?

A

give D5W

58
Q

SIADH

A
  • syndrome of inappropriate antidiuretic hormone; characterized by high circulating levels of ADH releative to plasma osm and serum sodium concentration
  • increased ADH causes kidneys to continue to reabsorb water despite presence of hyponatremia and hypotonicity of plasma
  • expansion of ICF and ECF occurs along with hemodilution and weight gain
  • urine - hypertonic relative to plasma and UOP low
59
Q

SIADH treatment

A
  • fluid restriction

- if patient symptomatic or serum sodium is <115-120, consider hypertonic saline

60
Q

clinical features of SIADH

A
  • water intoxication
  • dilution hyponatremia
  • brain edema
61
Q

s/s of brain edema

A
  • lethargy
  • HA
  • nausea
  • mental confusion
  • seizures
  • coma
62
Q

causes of SIADH

A
  • hypothyroidism
  • pulmonary infection
  • lung carcinoma
  • head trauma
  • intracranial tumors (neoplasms esp small cell carcinomas)
  • pituitary surgery
  • meds
63
Q

meds that cause SIADH

A
  • carbamazepine
  • tricyclic antidepressants
  • chloropropamide
  • cyclophosphamide
  • oxytocin
  • nicotine
  • clofibrate
64
Q

treatment of SIADH

A
  • mild = water restriction of 800-1000 mL/day
  • acute/severe hyponatremia = sodium concentration of <115-120; hypertonic
  • SLOWLY increase to prevent central pontine demyelination syndrome
  • serum sodium measured Q2H during treatment
65
Q

rate to increase sodium in SIADH

A

1-2 mEq/L/hr or 6-12 mEq/L in 24 hours

66
Q

preop eval of patient with SIADH

A
  • careful volume status eval
  • fluid restriction that involves isotonic solution
  • CVP/SVV/PPV can help guide vol replacement
  • measure UOP, urine osm, plasma osm, and plasma sodium
  • prevent nausea because this will increase release of ADH

N935 Advanced Pathophysiology II (16 decks)

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