Pituitary Gland Flashcards
1
Q
What are endocrine glands?
A
cells that secrete hormone directly into the surrounding ECF
2
Q
How are exocrine glands products expelled?
A
through ducts
3
Q
What are seven endocrine glands?
A
Thyroid Parathyroid Pituitary Pancreas Adrenal Placenta Ovaries and Testes
4
Q
What are the mediators of the endocrine system?
A
hormones
5
Q
What are hormones?
A
chemical messengers that transport information (a message) from one set of cells (endocrine cells) to another (target cells)
6
Q
What is an example of an endocrine function?
A
pituitary gland to thyroid gland
7
Q
What causes a response to a hormone?
A
primarily, the binding of hormone to its target cell receptor
8
Q
What characteristics of the hormone receptor help with hormone receptor binding?
A
high specificity and affinity
9
Q
Where is the receptor found?
A
location of the receptor directs the hormone to the correct target organ or target cell
10
Q
What is an example of a hormone that has numerous target sites?
A
insulin
11
Q
What is an example of a hormone that has one target tissue?
A
TSH
12
Q
What are three processes that regulate hormone secretion?
A
neural control
biorhythms
feedback mechanisms
13
Q
What hromones are under neural control?
A
ADH, catecholamines, cortisol
14
Q
How can neural control influence hormone secretion?
A
suppress or stimulate secretion
15
Q
What are types of stimulus for neural influence over hormones?
A
smell, touch, stress, sight, taste, pain
16
Q
What are biorhythms?
A
intrinsic hormonal oscillations may be circadian, weekly or seasonal
vary in stages of life
17
Q
What is the role of the pituitary?
A
collects and integrates information from almost everywhere in the body & uses information to control the secretion of vital pituitary hormones
18
Q
What is the pituitary gland regulated by?
A
feedback control from peripheral target organ hormones or other target products
19
Q
Do the pituitary and hypothalamus have a BBB?
A
No
20
Q
Why do the pituitary and hypothalamus lack a BBB?
A
allows for feedback to have a potent effect on the two structures
21
Q
Where is the pituitary gland located?
A
sella turcica at base of the brain
22
Q
What is the anterior lobe of the pituitary?
A
adenohypophysis
23
Q
What is the posterior lobe of the pituitary?
A
neurophypophysis
24
Q
What is blood supply to the pituitary?
A
superior and inferior hypophyseal arteries
25
What are the six hormones secreted by the anterior pituitary?
```
growth hormone
adrenocorticotrophic hormone
thyroid-stimulating hormone
follicle-stimulating hormone
luteinizing hormone
prolactin
```
26
What is the anterior pituitary target cell type for thyrotropin-releasing hormone?
thyrotroph
27
What is the anterior pituitary target cell type for corticotropin-releasing hormone?
corticotroph
28
What is the anterior pituitary target cell type for gonadotropin-releasing hormone?
gonadotroph
29
What is the anterior pituitary target cell type for prolactin-releasing hormone?
lactotroph
30
What is the anterior pituitary target cell type for prolactin-inhibiting hormone?
lactotroph
31
What is the anterior pituitary target cell type for growth hormone releasing hormone?
somatotroph
32
What is the anterior pituitary target cell type for growth hormone inhibitory factor hormone?
somatotroph
33
What is the anterior pituitary hormone release when thyrotroph is targeted?
thyroid stimulating hormone (TSH)
34
What is the target of TSH
thyroid gland
35
What is the primary peripheral feedback hormone for TRH?
T3
36
What is the anterior pituitary hormone released from corticotrophs
adrenocorticotropic hormone (ACTH, corticotropin)
37
What is the hormone target site of ACTH?
zona fasciculata & zona reticularis of adrenal cortex
38
What is the primary peripheral feedback hormone of CRH?
cortisol
39
What anterior pituitary hormone is released from gonadotrophs?
follicle-stimulating hormone lutenizing hormone
40
What are the target sites of LH and FSH
gonads (testes and ovaries)
41
What is the primary peripheral feedback hormone for GRH?
estrogen
progesterone
testosterone
42
What hormone does a lactotroph release?
prolactin
43
What is the target site of prolactin?
breast
44
Is there a primary feedback loop for prolactin secretion?
no
45
What is released from a somatotroph?
growth hormone
46
What is the target of growth hormone?
all tissues
47
What is the primary peripheral feedback hormone of somatotroph?
growth hormone, insulin, growth factor 1
48
What is a primary pituitary disorder?
defect to the peripheral endocrine gland
49
What is a secondary pituitary disorder?
defect to the pituitary
50
What is a tertiary disorder?
defect to the hypothalamus
51
What is panhypopituitarism?
generalized pituitary hypofunction
52
What causes anterior pituitary hyposecretion?
```
nonfunctioning tumors compress and destroy normal pituitary tissue
hypophysectomy
postpartum shock
irradiation
trauma
infiltrative disorders
```
53
What may be required if the tumor or pituitary gland causing hypopituitarism is removed?
thyroid hormone
glucocorticoids
vasopressin
54
what does removing the tumor or pituitary gland causing hypopituitarism do?
decompress or removes the tumor
| to control bleeding
55
What is anterior pituitary hypersecretion caused by?
bengin adenomas
56
What are the three most common tumors found in ant pituitary hypersecretion?
prolactin
ACTH
GH
57
what the symptoms of hyper-prolactin?
amenorrhea, infertility, decreased libido and impotence
58
what the symptoms of hyper-ACTH?
cushing's disease
59
what the symptoms pf hyper-growth hormone?
promotes growth of all tissues capable of growing
60
What type of tumors are very rare in hyper-secretion of the anterior pituitary?
thyrotropin and gonadotropin
61
What does growth hormone release reflect?
pulsatile fluctuations of GH releasing hormone and growth hormone regulate synthesis throughout the day
62
When do GH secretion increase?
stress, hypoglycemia, exercise adn deep sleep
63
Where does GH effect?
almost every part of the body
64
What is the major GH target?
liver
65
Why is the liver the major target of GH?
stimulates production of insulin-like growth factor type 1 (IGF-1) which mediates many of the effects of GH
66
What does GH and IGF1 cause?
skeletal muscle, heart, skin and visceral organs undergo hypertrophy and hyperplasia
67
How is hypersecretion of GH caused?
growth hormone secreting adenoma
68
What is hypersecretion of GH called in adults?
acromegaly
| sustained hypersecretion of GH after adolescence
69
What is hypersecretion of GH called prior to puberty?
gigantism
| hypersecretion of GH prior to the closure of growth plates
70
What are features of acromegaly?
```
skeletal overgrowth
soft tissue overgrowth
visceromegaly
osteoarthritis
glucose intolerance
skeletal muscle weakness
extrasellar tumor extension
peripheral neuropathy
```
71
What are comorbidities associated with acromegaly?
```
HTN
cardiomyopathy
ischemic heart disease
diabetes
osteoarthritis
skeletal muscle weakness/fatigue
increased lung volumes
sleep apnea
increased liver, spleen, kidneys and heart
```
72
What is the treatment for acromegaly?
restore normal GH levels
preferred initial treatment is microsurgical removal of the tumor with preservation of the gland
irradiation and/or suppressant drug therapy are adjunctive treatments or for non-surgical candidates
73
How are small GH tumors removed?
with a transphenoidal approach
74
How are larger GH tumors removed?
with an intracranial approach
75
What are options for nonsurgical candidates of acromegaly?
irradiation and/or suppressant drug therapy
76
Describe airway management for patients with acromegaly
```
enlarged tongue, lips and epiglottis,nasal turbinates
overgrowth of mandible
vocal cord dysfunction
upper airway obstruction
difficult mask fit
impaired visualization of cords
subglottic narrowing
dyspnea/ hoarsenes (larynx involved)
```
77
What percent of acromegaly patients have OSA?
60%
78
What happens post-operatively for surgical acromegaly patients?
postoperative respiratory obstruction or failure
79
What are anesthesia management considerations for acromegaly?
```
systemic HTN
ischemic heart disease
arrhythmias
skeletal muscle weakness
Hyperglycemia (glucose intolerance)
entrapment neuropathies common
```
80
If preanesthetic assessment (in acromegaly) reveals adrenal or thyroid axis impairment should be administered?
stress level glucocorticoid therapy and thyroid replacement
81
What does an entrapment neuropathy indicate?
perform allen's test prior to placing arterial line; confirm collateral blood flow
hypertrophy of carpal tunnel ligament may impede ulnar artery flow
82
What is necessary for pituitary surgery and preoperative preparation?
thorough medical history and physical
| concentrate of symptoms associated with acromegaly
83
What labs are needed pre-operatively for pituitary surgery?
electrolytes
glucose
hormone levels
84
What is the purpose of looking at images pre-operatively for pituitary surgery?
determine the extent of the tumor invasion
85
What can be seen on an EKG pre-operatively for pituitary surgery?
Left ventricular hypertrophy and arrhythmias
consider echocardiogram if the patient has cardiac dysfunction
optimize cardiac function prior to surgery
86
What are considerations for trans-sphenoidal approach?
head of bed is elevated 15
arterial line si usually inserted for BP monitoring
a lumbar drain is placed
consider monitoring for VAE (if tumor is large and invading large sinus and/or in steep head up position)
not a lot of blood loss
use of submuscosal injection of Epi containing solutions or use of topical vasoconstrictors can result in HTN
anesthestic technique should allow for muscle relaxation, smooth extubation and rapid neurologic assessment
intraoperative hypotension (maybe due to inaddequate cortisol secretion) requires replacement of hydrocortison 50-100mg IV
blood loss minimal; potential for large amounts of blood loss if a large cavernous sinus is inadevertly entered
DI
cranial nerve damage, epitaxis, hyponatremia, cerebral spinal fluid leaks
adequate fluid replacement
87
What are DI considerations?
can occur intra or postoperatively because of surgical trauma to the posterior pituitary (trauma reversible)
results in insufficient ADH
88
What is the diagnosis for DI?
diagnosis with serum electrolytes, plasma osmolarity and urine osmolarity
89
How do you treat DI?
intranasal desmopressin or restrict Na intake
90
What does the posterior pituitary secrete?
oxytocin
| antidiuretic hormone
91
Role of ADH
control renal water excretion and reabsorption and is a major regulator of serum osmolarity
92
Role of oxytocin
powerfully stimulates uterine contractions, stimulates myeopithelia cells of breast for milk ejection during lactation, is used for inducing labor and decreasing postpartum bleeding
93
What are the types of vasopressin receptors?
V1- mediates vasoconstriction
V2- mediates water reabsorption in renal collecting ducts
V3- found in the CNS and stimulate modulation of corticotrophin secretion
94
What are the ten stimuli for ADH release?
```
increased plasma sodium
increased sodium osmolality
decreased blood volume
smoking (nicotine)
pain
stress
nausea
vasovagal reaction
angiotensin 2
positive pressure ventilation
```
95
What occurs in ADH deficiency?
diabetes insipidus (DI)
96
what are the two types of DI
neurogenic and nephrogenic
97
What is neurogenic DI?
caused by inadequate release of ADH
98
What is nephrogenic DI?
renal tubular resistance to ADH
99
What are causes of neurogenic DI?
head trauma
brain tumors
neurosurgery
infiltrating pituitary leisons
100
What is associated with nephrogenic DI?
```
hypokalemia
hyperkalemia
genetic mutations
hypercalcemia
medication induced nephrotoxicity
```
101
What are inhibitors of ADH action or release?
```
ethanol
demeclocycline
phenytoin
chlorpromazine
lithium
```
102
What are symptoms of ADH deficiency?
```
polyuria
inability to produce concentrated urine
dehydration
hypernatremia
low urine osmolarity <300mOsm/L
urine specific gravity <1.010
urine volume > 2ml/kg/hr
Serum osmolarity > 290mOsm/L and sodium >145mEq/L
neurologic symptoms of hyperreflexia, weakness lethargy seizures and coma
```
103
What is the most common symptoms of ADH deficiency?
polyuria
104
What is the major mechanism for controlling DI in awake patients?
thirst
105
What is the treatment for mild/moderate DI?
medications that augment the release of ADH or increase receptor sensitivity
chlorpropramide (sulyfonurea hypoglycemia agent)
carbamazepine- anticonvulsant
clofibrate- hypolipidemic agent
106
What is the treatment for significant DI?
DDVAP
107
What is considered significant DI?
plasma osmolarity >290mOsm/L
108
What is DDAVP?
selective V2 agonist
less vasopressor activity
enhanced antidiuretic properties
administered SubQ, intranasal, IV
109
What is the DOA of vasopressin?
8-12 hours
110
What is the dose range for ADH?
5-40mcg/day nasally
| 0.5-2mcg/day BID SQ
111
What should be assessed in posterior pituitary pre-operative assessments?
careful assessment of plasma electrolytes, renal function and plasma osmolarity
dehydrate makes the patients very sensitive to the hypotensive effect of GA
intravascular volume should be replaced with isotonic fluids over 24-48hours
112
What is the pre-operative treatment for ADH deficiency?
Vasopressin is not alway recommended because surgical stress increases ADH secretion
measurement of plasma osmolarity, UOP and serum sodium during the intraopertive and immediate postoperative period
isotonic fluids during the intraoperative period & if the plasma osmolarity rises above 290 mOSm/L D5W should be administered (hypotonic solution shifts fluid into cells for the cell to swell)
113
What is the treatment for complete DI?
desmopressin 1-2mcg/kg IV/SQ intranasal spray BID
| aqueous vasopressin 5-10 unites IM/SQ q 8-12 hours
114
When should caution be used in DDAVP administration for complete DI?
if patient has CAD
| ADH substitutes like ADH causing hypertension due to arterial constriction
115
What is SIADH?
syndrome of inappropriate antidiuretic hormone
116
Describe SIADH
disorder characterized by high circulating levels of ADH relative to plasma osmolarity & serum sodium concentration
117
What does ADH secretion cause in the kidneys in SIADH?
kidneys will reabsorb water and despite the presence of hyponatremia and plasma hypotonicity
118
What occurs at a cellular level in SIADH?
expanison of ICF and ECF as well as hemodilution and weight gain
119
What is difference in the urine and plasma in SIADH
urine is hypertonic compared to plasma
| urine output is low
120
Serum osmolarity in SIADH
<270mOsm/L
121
Serum osmolarity in DI
> 290mOsm/L
122
Serum sodium in SIADH
<130mEq/L
123
Serum sodium in DI
> 145mEq/L
124
Urine Volume in SIADH
low
125
Urine Volume in DI
high > 2ml/kg/hr
126
Urine osmolarity in SIADH
hypertonic urine relative to plasmA
127
urine osmolarity in DI
hypotonic urine relative to plasma
128
Treatment of SIADH (chart)
fluid restriction
| if patient is symptomatic or serum sodium <115-120mEq/L consider hypertonic saline
129
Treatment of DI
DDVAP or vasopressin
130
What is the difference between desmopressin and vasopressin?
desmopressin has less vasoconstrictor effects then vasopressin
131
what are the three main clinical features of SIADH?
water intoxification
dilutional hyponatremia
brain edema
132
What are the severity of symptoms in SIADH determined by?
the degree of hyponatremia and rate of decrease in serum sodium
133
What are s/s of brain edema?
```
lethargy
headache
nausea
mental confusion
seizures
coma
```
134
What are causes of SIADH?
```
hypothyroidism
pulmonary infection
lung carcinoma
head trauma
intracranial tumors
pituitary surgery
```
135
What are medications that can cause SIADH?
```
carbamazepine
tricyclic antidepressants
chlorpropamide
cyclophosphamide
oxytocin
nicotine
clofibrate
```
136
What are intracranial tumors that cause SIADH?
neoplasm (especially small cell carcinomas of the lung are common)
ADH produced by these tumors are identical to that produced by the hypothalamus
137
How do you treat mild SIADH with no symptoms of hyponatremia?
treat with water restriction of 800-1000ml/day of NS
138
What is the treatment to SIADH with acute, severe hyponatremia with plasma sodium concentration of <115-120 emq/l or acute neurological symptoms
IV hypertonic saline with or without loop diuretic
139
How frequent should serum sodium be checked when treating SIADH?
2 hours
140
What are pre-operative evaluation for SIADH?
careful status evaluation
perioperative fluid management (fluid restriction that involves use of isotonic solution)
CVP can help with guiding volume replacement
frequent measures of urine output, urine osmolarity, plasma osmolarity, and serum sodium concentrations
prevent nausea because it is potent for releasing ADH
