M4-ENDOCRINOLOGY Flashcards
1
Q
What is the alternate name for the pituitary gland?
A
Pituitary Gland
2
Q
What is the weight and size of the pituitary gland?
A
0.6g (12mm transverse and 8mm anteroposterior)
3
Q
What is the Latin/Greek meaning of “pituitary”?
A
“Spit mucus”
4
Q
Why is the pituitary called the “master gland”?
A
Secretes hormones regulating metabolism
5
Q
What does “hypophysis” mean and why is it named so?
A
“Undergrowth” (located under the hypothalamus)
6
Q
What is the pituitary’s role in hormonal regulation?
A
Translates neural input into hormonal products via feedback mechanisms
7
Q
What are the three embryological parts of the pituitary gland?
A
Anterior pituitary (adenohypophysis)
8
Q
Where does the anterior pituitary originate from?
A
Rathke’s pouch (ectodermal oral cavity outpouching)
9
Q
What characterizes the intermediate lobe of the pituitary?
A
Poorly developed in humans and often confused with benign cysts on imaging
10
Q
What is the origin of the posterior pituitary?
A
Diencephalon neuroectoderm (stores oxytocin and vasopressin)
11
Q
Where is the pituitary gland anatomically located?
A
Sella turcica (sphenoid bone depression)
12
Q
How is the anterior pituitary primarily supplied with blood?
A
Hypothalamic-hypophyseal portal system (80-90% of blood supply)
13
Q
What structure connects the pituitary to the hypothalamus?
A
Infundibulum (pituitary stalk)
14
Q
What cell types are found in the anterior pituitary and what do they secrete?
A
Somatotrophs (GH)
15
Q
What hormones does the posterior pituitary store and release?
A
Vasopressin (ADH) and oxytocin (synthesized in the hypothalamus)
16
Q
What are the two types of feedback regulation in the endocrine system?
A
Feedback inhibition (suppression) and feedback stimulation (activation)
17
Q
When does pituitary function first become detectable during gestation?
A
7th-9th week
18
Q
What are the two broad categories of pituitary dysfunction?
A
Hormonal excess (e.g.
19
Q
Where are vasopressin and oxytocin synthesized?
A
Magnocellular neurons of the hypothalamic supraoptic and paraventricular nuclei
20
Q
How are posterior pituitary hormones transported to the gland?
A
Axonal transport through the infundibulum
21
Q
Why does the intermediate lobe confuse radiologists?
A
Appears as a non-functional benign cyst on imaging
22
Q
How does the endocrine system maintain hormone balance?
A
Hypothalamus-pituitary-endocrine gland feedback loops
23
Q
What are characteristics of the hypothalamic-hypophyseal unit’s functional aspects?
A
Similar response patterns for each pituitary hormone
24
Q
What are hypothalamic response patterns for pituitary hormones?
A
Similar secretion mechanisms for each hormone
25
What are feedback mechanisms influenced by external stimuli where hormones control their own regulation?
Open-loop feedback mechanisms
26
What are anterior pituitary hormones released in bursts with specific time intervals between releases?
Pulsatile hormone secretion
27
What are hormonal secretion patterns influenced by light-dark cycles (e.g.
ACTH peaks at 6-9 AM)?
28
What is the process of synchronizing external light/dark cues with internal biological clocks?
Zeitgeber (“time giver”)
29
What is the feedback mechanism where TRH → TSH → thyroxine suppresses TRH/TSH when thyroxine is sufficient?
Hypothalamic-pituitary-thyroid axis feedback
30
What are the three feedback loops where thyroxine acts on hypothalamus (long-loop)
pituitary (short-loop)
31
What are hypothalamic hormones that regulate anterior pituitary function (e.g.
TRH
32
What is the hypothalamic hormone that stimulates both TSH and prolactin secretion?
TRH
33
What is the hypothalamic hormone that stimulates concurrent LH and FSH production?
GnRH
34
What is the hypothalamic hormone that inhibits GH and TSH release?
Somatostatin (SS)
35
What is the hormone that regulates water metabolism via ADH and stimulates ACTH secretion?
Vasopressin
36
Where are hypophysiotropic hormones found besides the hypothalamus?
Central nervous system
37
What is the hormone primarily regulated through feedback inhibition (dopamine suppression) rather than stimulation?
Prolactin
38
What is the main hypothalamic stimulus for ACTH secretion?
CRH (corticotrophin-releasing hormone)
39
What causes elevated prolactin levels when secretion is high?
TRH
40
What is the structure connecting the hypothalamus to the pituitary gland?
Infundibulum (pituitary stalk)
41
What is the vascular system transporting hypothalamic hormones directly to the anterior pituitary?
Hypophyseal portal system
42
What is the neural tract carrying oxytocin/ADH from hypothalamus to posterior pituitary?
Hypothalamohypophyseal tract
43
What are the TSH-producing cells in the anterior pituitary?
Thyrotrophs
44
What is the process where thyroxine suppresses TRH production and TSH secretion?
Negative feedback inhibition
45
What is the feedback loop where hormones act directly on the hypothalamus?
Long-loop feedback
46
What is the feedback loop where pituitary hormones inhibit hypothalamic release?
Ultrashort feedback loop
47
What is the physiological pattern maintaining target organ responsiveness through intermittent hormone release?
Pulsatile secretion
48
What is the clinical relevance of ACTH’s lowest secretion between 11 PM-3 AM?
Basis for morning cortisol testing
49
What is the anatomical site where hypothalamic hormones enter the hypophyseal portal system?
Median eminence
50
What are anterior pituitary hormones larger and more complex than?
Hypothalamic hormones (TRH
51
What are the two types of anterior pituitary hormones?
Direct effectors (act on peripheral tissue) and tropic hormones (target other endocrine glands)
52
What anterior pituitary hormone affects substrate metabolism and stimulates liver growth factors?
Growth hormone (GH)
53
What type of hormone specifically targets other endocrine glands?
Tropic hormones (LH
54
What does luteinizing hormone (LH) stimulate in males?
Testosterone production from Leydig cells
55
What does luteinizing hormone (LH) stimulate in females?
Ovulation
56
What does follicle-stimulating hormone (FSH) trigger in females?
Ovarian recruitment and folliculogenesis
57
What does follicle-stimulating hormone (FSH) initiate in males?
Spermatogenesis
58
What does thyroid-stimulating hormone (TSH) regulate?
Thyroid hormone production
59
What does adrenocorticotropic hormone (ACTH) control?
Adrenal steroidogenesis (aldosterone
60
What percentage of people have clinically silent pituitary adenomas?
Up to 20% based on autopsy studies
61
What imaging findings are observed in normal individuals regarding pituitary lesions?
10%–30% show pituitary abnormalities on MRI
62
What surgical approach removes pituitary tumors via the sphenoid sinus?
Transsphenoidal surgery
63
When does physiologic pituitary enlargement occur?
During puberty and pregnancy
64
What is the most common type of pituitary tumor?
Prolactin-secreting tumors
65
What are non-functional pituitary tumors called?
Null cell tumors
66
What defines atypical pituitary tumors?
MIB-1 >3%
67
What is MIB-1 used to detect?
KI-67 antigen (cell proliferation marker)
68
What role does p53 play in atypical pituitary tumors?
Tumor suppressor gene with antiproliferative effects (often mutated)
69
How are pituitary tumors ≥1 cm classified?
Macroadenomas
70
How are pituitary tumors <1 cm classified?
Microadenomas
71
What hormone stimulates adrenal cortisol production?
Adrenocorticotropic hormone (ACTH)
72
What hormone directly regulates thyroid hormone synthesis?
Thyroid-stimulating hormone (TSH)
73
What hormone initiates milk production in breasts?
Prolactin (PRL)
74
What hormones are collectively called gonadotropins?
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
75
What hormonal change occurs with prolactin-secreting tumors?
Elevated prolactin levels (hyperprolactinemia)
76
What diagnostic step precedes pituitary tumor diagnosis?
Clinical evaluation and laboratory testing
77
What surgical term describes drilling through the sphenoid sinus?
Transsphenoidal approach
78
What cell abnormality do pathologists describe as "atypia"?
Abnormal shape
79
What is the most abundant pituitary hormone?
Growth hormone (somatotropin)
80
What hormones are structurally related to growth hormone?
Prolactin and human placental lactogen
81
What type of hormone is growth hormone?
Direct effector (acts on peripheral tissues)
82
What cells produce growth hormone?
Somatotrophs in the anterior pituitary
83
What stimulates growth hormone secretion?
Growth hormone-releasing hormone (GHRH)
84
What inhibits growth hormone secretion?
Somatostatin (SS)
85
What is the secretion pattern of growth hormone?
Pulsatile release (peaks at sleep onset
86
How does growth hormone affect insulin's action?
Directly antagonizes insulin's effects on glucose metabolism
87
What metabolic process does growth hormone stimulate in the liver?
Hepatic gluconeogenesis
88
What condition accompanies GH deficiency in children?
Hypoglycemia
89
What does growth hormone enhance in skeletal muscle?
Protein synthesis
90
What growth factors does GH stimulate?
Insulin-like growth factors (somatomedins)
91
What is the major GH-induced growth factor used clinically?
IGF-1 (somatomedin C)
92
What condition results from pathologic GH excess?
Acromegaly
93
What percentage of acromegaly patients have co-secreted prolactin?
Up to 40%
94
What occurs with GH-secreting tumors before epiphyseal closure?
Gigantism
95
What physical changes occur in acromegaly?
Bony/soft tissue overgrowth (hands
96
What metabolic complications accompany acromegaly?
Diabetes
97
What organ enlargement occurs in acromegaly?
Thyromegaly (unless tumor co-secretes TSH)
98
What is the life expectancy impact of untreated acromegaly?
Reduced due to cardiovascular risks
99
What is the surgical treatment for pituitary tumors?
Transsphenoidal adenomectomy
100
What radiation therapy is used for large invasive tumors?
External beam radiation therapy
101
What drugs suppress GH in acromegaly?
Somatostatin analogs (octreotide/lanreotide)
102
When are dopaminergic agonists effective in acromegaly?
Only if tumors co-secrete prolactin
103
What GH receptor antagonist treats acromegaly?
Pegvisomant
104
What is the screening test for GH abnormalities?
IGF-1 (somatomedin C) levels
105
What confirms acromegaly diagnosis?
Failed GH suppression (<1 ng/mL) during 75g OGTT
106
What happens to IGF-1 in acromegaly?
Increased levels
107
What happens to IGF-1 in GH deficiency?
Decreased levels
108
What metabolic effect causes acromegaly-related diabetes?
GH-induced insulin resistance and gluconeogenesis
109
What sleep disorder occurs in acromegaly?
Sleep apnea
110
What musculoskeletal complication develops in acromegaly?
Debilitating arthritis
111
What is the primary clinical use of IGF-1 measurements?
Evaluating GH deficiency/excess
112
What condition affects growth in children and body composition in adults?
Growth hormone deficiency (GHD)
113
What causes GH deficiency in children?
Familial factors or pituitary tumors
114
What causes GH deficiency in adults?
Structural/functional pituitary abnormalities
115
What genetic mutations are linked to GH deficiency?
Recessive GHRH gene mutation
116
What structural issues cause GH deficiency?
Pituitary/hypothalamic lesions
117
What syndrome in adults involves osteoporosis and altered body composition?
Adult GH deficiency syndrome
118
What is the primary treatment for GH deficiency?
GH replacement therapy
119
What screening test uses exercise to stimulate GH release?
Physical activity test
120
What is the gold standard confirmatory test for GH deficiency?
Insulin tolerance test
121
What is the alternative confirmatory test for GH deficiency?
Arginine stimulation test
122
What GH level indicates deficiency in adults during testing?
Failure to rise >5 ng/mL
123
What GH level indicates deficiency in children during testing?
Failure to rise >10 ng/mL
124
What hormone is structurally related to GH and human placental lactogen?
Prolactin
125
What is the primary inhibitor of prolactin secretion?
Dopamine
126
What is prolactin's key physiological function?
Lactation initiation/maintenance
127
What is the most common functional pituitary tumor?
Prolactinoma
128
What symptoms occur in premenopausal women with prolactinomas?
Menstrual irregularity
129
What symptoms occur in men with prolactinomas?
Reduced libido
130
What medications cause hyperprolactinemia?
Antipsychotics (phenothiazines)
131
What pituitary structure disruption causes hyperprolactinemia?
Pituitary stalk (infundibulum) damage
132
What thyroid hormone increases prolactin secretion?
TRH (thyrotropin-releasing hormone)
133
What conditions besides tumors cause hyperprolactinemia?
Renal failure
134
What is the consequence of prolonged prolactin excess?
Hypogonadism (reduced FSH/LH)
135
Why do lactating mothers experience suppressed ovulation?
High prolactin levels inhibit gonadotropin release
136
What tests evaluate hyperprolactinemia causes?
TSH/free T4 levels
137
What are prolactinoma treatment goals?
Reduce tumor mass
138
What medical therapy treats prolactinomas?
Dopamine agonists (cabergoline
139
What surgical approach removes prolactinomas?
Transsphenoidal adenomectomy
140
When is radiotherapy used for prolactinomas?
For macroadenomas with local invasion
141
What test assesses pituitary anatomy in prolactinoma cases?
Sellar MRI
142
What hormone deficiency causes hypoglycemia in children?
Growth hormone deficiency
143
What facial features occur in severe childhood GH deficiency?
Maxillary hypoplasia
144
What diagnostic step precedes GH deficiency testing?
Rule out thyroid deficiency and familial short stature
145
What physical sign suggests GH deficiency in infants?
Micropenis (with congenital hypopituitarism)
146
What neonatal complications occur with severe GH deficiency?
Hypoglycemia
147
What body composition change occurs in GH-deficient children?
Mild-to-moderate chubbiness (increased body fat)
148
What growth velocity indicates GH deficiency before age 4?
<6 cm/year
149
What bone age finding suggests GH deficiency?
>2 years behind chronological age
150
What treatment improves adult GH deficiency symptoms?
GH replacement therapy (reduces body fat
151
What genetic syndrome might include GH deficiency?
Midline defects (cleft palate) with pituitary abnormalities
152
What occurs in hypopituitarism when pituitary/hypothalamus function fails?
Loss of anterior pituitary hormones (panhypopituitarism if complete
153
What replaces normal pituitary tissue to cause hypopituitarism?
Pituitary tumors
154
What trauma mechanism disrupts hypothalamic-pituitary communication?
Severe head trauma damaging infundibulum or pituitary stalk
155
What radiation effect causes hypopituitarism?
Damage from pituitary tumor radiotherapy
156
What postpartum condition causes pituitary necrosis?
Sheehan’s syndrome (from severe hypotension/hemorrhage)
157
What infections lead to hypopituitarism?
Fungal infections
158
What infiltrative diseases affect pituitary function?
Hemochromatosis
159
What autoimmune disorder causes pituitary lymphocytic infiltration?
Lymphocytic hypophysitis
160
What genetic condition involves deficient GnRH?
Kallmann syndrome (familial panhypopituitarism)
161
What hormones are replaced in panhypopituitarism treatment?
Thyroxine
162
What is infused for Kallmann syndrome?
GnRH to stimulate gonadotropin release
163
What does the posterior pituitary store/release?
Oxytocin and vasopressin (ADH)
164
What is oxytocin’s role in childbirth?
Induces uterine contractions (synthetic Pitocin used clinically)
165
What is vasopressin’s primary function?
Promotes water reabsorption in kidneys
166
What triggers vasopressin release?
Increased plasma osmolality (osmoreceptors) or hypovolemia (baroreceptors)
167
What deficiency causes diabetes insipidus?
Vasopressin deficiency (polyuria
168
What clotting factors does vasopressin affect?
Factor VII and von Willebrand factor (vWF) release
169
What monitors plasma osmolality for vasopressin regulation?
Hypothalamic osmoreceptors
170
What blood pressure drop triggers vasopressin release?
5-10% arterial pressure decrease
171
What stores but does not synthesize posterior pituitary hormones?
Posterior pituitary (neurohypophysis)
172
What is the structural relationship between oxytocin and vasopressin?
Both cyclic nonapeptides with disulfide bridges
173
What causes postpartum hypopituitarism?
Sheehan’s syndrome from pituitary infarction during delivery
174
What is the autoimmune mechanism of lymphocytic hypophysitis?
Lymphocyte infiltration impairing pituitary function
175
How does Kallmann syndrome present?
Hypogonadism with anosmia (due to GnRH deficiency)
176
What is the treatment goal for panhypopituitarism?
Hormone replacement to restore metabolic/sexual function
177
What is the clinical triad of diabetes insipidus?
Polyuria
178
What surgical approach treats pituitary stalk trauma?
Transsphenoidal repair if accessible
179
What imaging detects pituitary structural abnormalities?
Sellar MRI with contrast
180
What hormone deficiency causes adrenal insufficiency in hypopituitarism?
ACTH deficiency
181
What lab findings suggest hypopituitarism?
Low T4
