Week 2 - Ant. Pituitary Flashcards
1
Q
The pituitary gland lies in the _____ ______ just below the hypothalamus.
A
Sella turcica (“bony saddle”)
2
Q
Pituitary is connected to the hypothalamus
by a little stalk called the _________,
which contains nerve fibers and small blood
vessels
A
infundibulum
3
Q
The pituitary gland is composed of what 3 major parts?
A
Anterior
Posterior
Intermediate
4
Q
What does the intermediate lobe of the pituitary gland secrete?
A
melanocyte stimulating hormone (MSH)
5
Q
T/F: Most hypothalamic & pituitary hormones
are released in a pulsatile or burst-like
manner
A
True
6
Q
What are the 5 hormones secreted by the Anterior Pituitary?
A
- Growth hormone (GH)
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Gonadotropic hormones (FSH, LH)
- Prolactin (PRL)
7
Q
T/F: The posterior pituitary is really a neural
extension of the hypothalamus
A
True
8
Q
What are the 2 hormones secreted by the Posterior Pituitary?
A
- Antidiuretic hormone (ADH)
2. Oxytocin
9
Q
What is the other name for the anterior pituitary?
A
Adenohypophysis
10
Q
What is the other name for the posterior pituitary?
A
Neurohypophysis
11
Q
What is the other name for growth hormone secreted by the anterior pituitary? Which cells secrete them?
A
Somatropin; secreted by somatotrophs
12
Q
What is the hypophysiotropic hormone related to growth hormone?
A
Growth hormone releasing hormone (GHRH)
13
Q
What are 9 stimulators of growth hormone release?
A
- Hypoglycemia/fasting
- Glucagon
- Ghrelin
- Estrogen
- Androgens (during puberty)
- Strenuous exercise
- Nicotine
- Vit B3
- Deep Sleep
14
Q
What is the secretion amount of growth hormone in young adolescents and healthy adults?
A
Young adolescents: 700mcg/day
Healthy adults: 400mcg/day
15
Q
Secretion is greatest about ____ hour/s after sleep onset.
A
1 hour
16
Q
T/F: Nearly 50% of total GH secretion occurs during slow-wave sleep. What stage of sleep is this?
A
True; Stage 3 and 4 of NREM sleep
17
Q
T/F: Sleep deprivation increases growth hormone release.
A
FALSE! It suppresses growth hormone release
18
Q
What are 4 inhibitors of growth hormone?
A
- Somatostatin (Growth-hormone inhibiting factor)
- Hyperglycemia, increased free fatty acids
- Glucocorticoids (cortisol)
- Increased Dihydrotestosterone
19
Q
Growth hormone is primarily a/an _________ hormone
A
anabolic
20
Q
Growth hormone increase height in childhood by stimulating multiplication of which cells?
A
Chondrocytes
21
Q
Excess growth hormone secretion in childhood is which disorder?
A
Pituitary gigantism
22
Q
Prolonged growth hormone excess after closing of epiphyseal plates, causing thick bones in jaw, fingers, and toes is which disorder?
A
Acromegaly
23
Q
Growth hormone stimulates production of insulin-like growth factor (IGF-1,2) from the liver. What are 6 effects of this on peripheral tissue?
A
- ↑ muscle mass
- Promotes lipolysis
- ↑ protein synthesis
- ↓ liver uptake of glucose
- Stimulates immune system
- Improve calcium retention
24
Q
Adreno-corticotropic hormone (ACTH) is also known as ________ and is secreted by which cells in the anterior pituitary?
A
Corticotropin; corticotrophs
25
What is a hypophysiotropic hormone related to ACTH? What does it do?
Corticotropin-releasing hormone (CRH); stimulates ACTH in a pulsatile manner
26
What is the function of ACTH?
Stimulates adrenal cortex to release corticosteroids (specifically from the zona fasciculate & zona reticularis)
27
Which cells secrete thyroid-stimulating hormone (TSH)?
Thyrotrophs
28
Which sex hormone will increase sensitivity of thyrotrophs to TRH?
Estrogens
29
What is the hypophysiotropic hormone for TSH?
Thyrotrophin-releasing hormone (TRH)
30
What are 3 inhibitors of TSH?
1. Somatostatin
2. Dopamine
3. Cortisol
31
How does cortisol inhibit TSH?
It impairs sensitivity of the pituitary to TRH; may lower serum to undetectable levels
32
What are 3 functions of TSH?
1. Thyroid hormone secretion (T4 and T3)
2. Hyperplasia/hypertrophy of thyroid gland
3. Vascularization of thyroid gland
33
_____ is the primary marker used to assess thyroid function.
TSH
34
T/F: Levels of TSH are proportional to the concentration of
| thyroid hormone in the plasma
FALSE! Levels are inversely proportional
35
Which 2 hormones are secreted by cells called gonadotrophs?
FSH and LH
36
What is the hypophysiotropic hormone related to FSH and LH?
Gonadotropin-releasing hormone (GnRH)
37
What is the overall function of FSH?
Stimulates growth of germ cells
38
What is the function of FSH in women? Which form of estrogen levels rise?
Ovary: stimulates growth of Graafian follicles to maturation; estradiol levels rise
39
What is the function of FSH in men?
Testes: stimulates spermatogenesis
40
What role does cortisol play in relation to LH?
Inhibits gonadotroph response to GnRH
41
Low frequency pulses of GnRH will produce secretion of which hormone? High frequency?
Low: FSH
High: LH
42
What is the overall function of LH?
Stimulates sex-hormone secretion
43
What is the function of LH in females?
Ovary: acute rise in LH (LH surge) triggers ovulation; stimulates corpus luteum development and secretion of progesterone
44
What is the function of LH in males?
Testes: Stimulates Leydig cells to produce testosterone
45
Prolactin is secreted by which anterior pituitary cells?
Lactotrophs
46
Which substances or physical stimulus increases prolactin secretion?
1. Serotonin
2. Stressors (surgery, exercise, hypoglycemia, acute MI)
3. Nipple stimulation (in non-PG women)
47
What substance binds to lactotrophs and inhibits prolactin secretion?
Dopamine
48
What does Bromocriptine do to prolactin secretion?
Decreases it
49
What does dopamine agonists do to prolactin secretion?
Increases it
50
Extrapituitary secretion of prolactin occurs in T-cells, where are receptors found?
Prolactin receptors found in T & B-cells, macrophages
51
What are the 3 functions of prolactin related to breasts?
1. Promotes lactation
2. Increases breast size
3. Sodium retention
52
What are the 3 functions of prolactin related to sexual gratification?
1. Suppresses ovulation, fertility
2. Suppresses sexual arousal (opposes dopamine)
3. Accounts for male "refractory" period after sex
53
Elevated prolactin leads to _____________ which interferes with pulsatile secretion of LH & FSH.
Hypogonadism
54
Elevated prolactin in women can lead to shortening of which phase? What is the result?
Shortens luteal phase; results in annovulation, oligomenorrhea/amenorrhea, and infertility
55
Elevated prolactin in men can lead to decreased synthesis of which hormone? What is the result?
Decreased testosterone synthesis; results in decreased spermatogenesis, low libido, impotence, and infertility
56
What is the preferred method for visualizing the hypothalamus-pituitary?
MRI (with or without contrast)
57
What is the most common type of hypothalamic-pituitary abnormality?
Pituitary adenoma (10-25% of all intracranial neoplasms)
58
What are 3 types of pituitary adenomas?
1. Benign adenoma
2. Invasive adenoma
3. Carcinoma
59
Are the majority of adenomas: micro-adenomas or macro-adenomas?
Microadenoma
60
What is the disease associated with hyper secretion of ACTH?
Cushing's Disease
61
What is the most common s/sx of prolactinoma?
Galactorrhea
62
What is the most frequent manifestation of functional adenomas? What is this due to?
Hypogonadism; suppression of GnRH function from elevated prolactin, ACTH, and GH
63
T/F: Panhypopituitarianism is a very common condition associated with functional adenomas.
FALSE! They are less common (<20%)
64
Invasive adenomas: sellar enlargement causes which 2 things?
1. Headaches
| 2. Visual loss/changes
65
T/F: Patients presenting with bitemportal hemiaopsia or unexplained visual field defects or visual loss should be considered to have a pituitary or hypothalamic disorder until proven otherwise.
True
66
T/F: Pituitary adenomas in children are common
FALSE! They are rare. Most common are craniopharyngiomas and other hypothalamic tumors.
67
Enlargement of a pituitary mass may cause which 2 things?
1. Mass effect
| 2. Stalk effect
68
Mass effect of the pituitary causes which 2 problems?
1. Exert pressure on nearby tissues
| 2. Intracranial pressure
69
The stalk effect causes what problem?
Secretion of large amounts of prolactin
70
How is primary hypopituitarism caused?
Destruction of the pituitary
71
How is secondary hypopituitarism caused?
Deficiency of hypothalamic stimulatory factors
72
What percent of the anterior pituitary must be destroyed for symptoms to manifest from hormonal deficit?
75%
73
What are 6 causes of hypopituitarism?
1. Pituitary adenoma
2. Pituitary apoplexy
3. Sheehan syndrome
4. Empty sella syndrome
5. Trauma
6. Infiltrative conditions
74
Which hypopituitarism condition has spontaneous hemorrhage of the pituitary, usually into a pre-existing adenoma? Symptoms include sudden onset HA and diplopia.
Pituitary apoplexy
75
What is the most common cause of ischemic necrosis of the pituitary?
During pregnancy anterior pituitary enlarges, but the blood supply does not increase: pituitary prone to ischemia
During delivery, hemorrhage & shock may occur, resulting in further underperfusion of the anterior pituitary
May cause pituitary collapse,
failure to lactate, amenorrhea following pregnancy & hypothyroidism are often the first symptoms
Sheehan syndrome (“Post-partum necrosis of the pituitary”)
76
Which condition occurs when the subarachnoid space extends into the sella turcica, partially filling it with cerebral spinal fluid and causes enlargement of the sella, flattening the pituitary gland?
Empty Sella Syndrome
77
Which type of sella syndrome results from congenital incompetence of the diaphragm sellae? It is the most frequent cause of enlarged sella turcica, is associated with obesity & hypertension in women, and can be a sign of idiopathic intracranial hypertension.
Primary
78
Which type of sella syndrome causes: pituitary gland regression after an injury, surgery, or radiation therapy, postpartum pituitary infarction (Sheehan syndrome), PRL or GH-secreting pituitary adenomas. May undergo
hemorrhage with infarction & cause contraction of the
overlying suprasellar cistern downward into the sella.
Secondary
79
What is the most common clinical feature of empty sella syndrome?
Headache (approx 48%)
80
T/F: Empty sell syndrome usually doesn't need treatment, but should be differentiated from pituitary adenomas
True
81
Which condition has a short stature resulting from a medical condition caused by abnormal/slow growth?
Dwarfism
82
Between achondroplasia and pituitary dwarfism, which is more commonly the cause of dwarfism?
Achondroplasia (approx 70% of cases)
83
Which form of dwarfism is generalized slow growth where patients do not go through puberty?
Treatments for this condition include replacement of relevant hormones.
Panhypopituitarism (~2/3 of cases)
84
Which form of dwarfism do patients generally undergo normal sexual maturation and they are capable of having children?
Isolated growth hormone deficiency (~1/3 of cases)
85
Peak incidence of pituitary adenomas is between which ages?
30-60 y/o
86
T/F: Pituitary adenomas are mostly isolated, solitary lesions w/out associated neoplasms
True
87
Approx. 10% of pituitary adenomas are considered_______, being asymptomatic and non-functional
Incidentalomas
88
Approx ____% of pituitary adenomas are associated with multiple endocrine neoplasia (MEN) type 1
3
89
T/F: Pituitary adenomas are usually composed of multiple cell types that all secrete different hormones
FALSE! They are usually composed of a single cell type that secretes a single hormone (i.e. lactotrophs secreting prolactin)
90
Which pituitary adenoma is associated with elevated plasma prolactin, and interferes with HPG-axis?
Prolactinoma
91
What are 2 pharmaceutical treatment options for treating a prolactinoma?
Bromocriptine and Cabergoline
92
What are 3 ND treatments for a prolactinoma?
1. Vitex agnus-castus
2. Dopamine synthesis cofactors (B6, folate, tyrosine, Mg)
3. GABA
93
What is the second most common functional adenoma of anterior pituitary, subtle changes in growth (e.g. shoe size) may be the first symptoms?
Growth hormone (somatotropin) adenoma
94
What is a general increase in body size from excessive growth hormone secretion that occurs before growth plates close at the ends of the long bones (in children, teens)?
Gigantism
95
Which condition has effects of excessive growth hormone that occurs after the growth plates have closed (late teens, adults). It has physical symptoms of growth of bones in hand, feet, face, skull, jaw (jaw protrusion w/ spreading of teeth, & growth of viscera, skin, soft tissue, prominent brows, gapped teeth, huge feet and hands; usually not excessively tall or large overall; coarsening of facial features
Can also see secondary diabetes (via insulin resistance), hypertension, muscle weakness, congestive heart failure (diastolic dysfunction), arthritis, obstructive sleep apnea, and osteoporosis
Acromegaly
96
What are 4 therapeutic interventions used for treating growth hormone adenomas?
1. Transsphenoidal microsurgery
2. Somatostatin analogues (ocreotide acetate or LAR)
3. Dopamine agonists (Cabergoline)
4. GH receptor antagonist (Pegvisomant)
97
Which condition has ACTH hypersecretion resulting in elevated cortisol levels? It results from microadenomas <10mm in diameter and causes bilaterial adrenal hyperplasia. Circadian rhythm of ACTH secretion is suppressed, there is abnormal negative feedback in the HPA-axis. Usual age of onset is 20-40 years
Cushing disease
98
Which condition has the following characteristics?
- Obesity (with central fat pattern), round (moon) face, hirsutism, easy bruising, poor wound healing, purple striae
- Presence of hypertension, diabetes,osteopenia/osteoporosis, superficial fungal infections, and menstrual/mental abnormalities
Cushing’s Syndrome
99
What are the 3 screening tests for diagnosing Cushings disease?
When diagnosing, pick 2 of the 3:
1. 24-hour free urine cortisol
2. Elevated midnight salivary cortisol on 2 separate nights
3. 1 mg dexamethasone suppression test (positive if AM cortisol is persistently
elevated in the morning after administration of dexamethasone)
100
What are the 4 medications used to treat Cushing's syndrome?
No drug currently successfully suppresses ACTH secretion
- Ketoconazole: inhibits adrenal steroid synthesis
- Metyrapone: blocks cortisol synthesis
- Aminoglutethimide
- Mitotane: adrenolytic: causes adrenal atrophy
