Endocrinology Part 2 Flashcards
1
Q
What cell types release hormones from the anterior pituitary?
A
Corticotroph Gonadotroph Somatotroph Thyrotroph Lactotroph
2
Q
What do corticotrophs release?
A
ACTH
3
Q
What do gonadotrophs release?
A
LH
FSH
4
Q
What do somatotrophs release?
A
GH
5
Q
What do thyrotrophs release
A
TSH
6
Q
What do lactotrophs release?
A
PRL
7
Q
What stimulates corticotrophs?
A
CRH
8
Q
What stimulates gonadotrophs?
A
GnRH
9
Q
What inhibits gonadotrophs?
A
PRL
10
Q
What stimulates somatotrophs?
A
GHRH
11
Q
What inhibits somatotrophs?
A
SST
12
Q
What inhibits thyrotrophs
A
SST
13
Q
What stimulates thyrotrophs?
A
TRH
14
Q
What stimulates lactotrophs?
A
TRH
15
Q
What inhibits lactotrophs?
A
DA
16
Q
Which cells do TRH stimulate?
A
thyrotrophs
lactotrophs
17
Q
Which cells do SST inhibit?
A
Somatotroph
Thyrotroph
18
Q
At what receptor does prolactin act?
A
Cytokine receptor
19
Q
What does prolactin do during pregnancy?
A
Stimulate breast development to prepare for lactation
20
Q
What do estrogens released from the placenta do during pregnancy?
A
Inhibit milk production (so no milk is produced before baby arrives)
21
Q
What does prolactin do post-partum?
A
Stimulate milk production and lactation
22
Q
What inhibits the release of prolactin?
A
Dopamine
23
Q
What stimulates the release of prolactin?
A
Pregnancy
Nursing
High TRH
Sleep
24
Q
What can cause hyperprolactinemia?
A
Prolactinoma (tumor in the ant. pit.)
High TRH (due to hypOthyroidism)
Hypothalamic/pituitary stalk damage
DA-R antag
25
What is seen in women with hyperprolactinemia?
Galactorrhea
```
Low levels of LH, FSH, and estrogen -->
amenorrhea
anovulation
infertility
decreased libido
dry skin
```
26
What is seen in men with hyperprolactinemia?
Low levels of LH, FSH, and testosterone -->
decreased libido
impotence
infertility
Minor galactorrhea
27
How is hyperprolactinemia treated?
D2 receptor agonists (particularly useful for tumors) --> cabergoline
bromocriptine
Surgery (remove the tumor)
28
What actions are INCREASED by growth hormone acting at the cytokine receptor?
```
INC:
plasma glucose
gluconeogenesis
lipolysis
IGF-1 release
```
Have some growth
29
What actions does growth hormone have after IGF-1 is released from liver, muscle fat, and bone?
```
Growth:
bones
organs
glands
muscle
skin
```
30
What can stimulate the release of growth hormone?
```
GHRH
Low glucose
AA (arginine)
Ghrelin
Puberty
Sleep
```
31
What can INHIBIT the release of growth hormone?
```
SST
GH
IGF-1
High glucose
High FFA
Age
Emotional stress
```
32
What can cause growth hormone DEFICIENCY?
Decreased GHRH release from the hypothalamus
Damage to the anterior pituitary
Non-functional GH (gene defect)
33
What decreases are seen clinically in growth hormone deficiency?
DEC:
strength
muscle mass
height in kids
34
What stimulation tests are used to measure low growth hormone?
GHRH + arginine infusion
Insulin-induced hypoglycemia
If normal = GH will increase
If abnormal = GH will not increase adequately
35
How can you treat growth hormone deficiency?
Administer recombinant GH (somatropin)
36
What can cause EXCESS growth hormone?
Pituitary adenoma
Hypothalamic overproduction of GHRH
Exogenous GH
37
What is seen clinically with excess growth hormone?
Acromegaly
```
Children = gigantism
Adults = normal height
```
38
What suppression test can be done to test for growth hormone excess?
Oral glucose test
```
Normal = decrease GH
Abnormal = GH will not decrease adequately
```
39
How can you TREAT growth hormone EXCESS?
Surgery of the tumor
Octreotide - SST analog
Pegvisomant (GH receptor antagonist) - decreases GH activity and inhibits release of IGF-1
40
What does C cells produce? What is another name for C cell?
Calcitonin
Parafollicular cell
41
Where does iodine trapping occur?
From blood to follicular cell
42
Where does organification occur? What enzyme does this?
In the colloid
TPO (thyroid peroxidase)
43
What drugs inhibit thyroid peroxidase?
Methimazole and PTU (propylthiouracil)
44
What is the radioactive iodide uptake test (RAIU)?
Give a patient radioactive iodide and measure it's take up by the thyroid
If the patient has high TSH-R activity or hyperactive nodules/tumors it will show up as bright spots
This means the patient has higher than normal iodide trapping and organification
45
What does TSH do? (4 items)
1. Increase iodide trapping
2. Increase TPO activity
3. Increase hormone synthesis and release
4. Increase thyroid gland growth
46
What is euthyroid hyperthyroxinemia?
No symptoms off thyroid hormone excess or deficiency = normal levels of free hormone
High levels of total hormone
47
What is euthyroid hypothyroxinemia?
No symptoms off thyroid hormone excess or deficiency = normal levels of free hormone
Low levels of total hormone
48
What can cause euthyroid hyperthyroxinemia?
Slow increase in TBG binding
Estrogens and 5-FU
49
What can cause euthyroid hypothyroxinemia?
Slow decrease in TBG binding
Androgens, niacin, and aspirin
50
What converts T4 to T3?
5'-deiodinase (non-prime form creates a non-active form)
51
What does thyroid hormone do? (items 1-5)
1. Linear growth = normal growth, development, and function of tissues
2. Increase metabolism
3. Increase HR and oxygen use by heart
4. Vasodilation
5. Tremor (increase beta2 receptors)
52
What is the MOA of thioamides?
Decrease TPO activity --> thyroid hormone synthesis
Methimazole and PTU
53
What does thyroid hormone do? (items 6-10)
6. Increase EPO release from kidney
7. Increase GI motility
8. Increase bone resorption
9 Increase deep tendon reflex
10. Increase drug/hormone metabolism
54
How long does it take for thioamide to reach maximum efficacy?
3-6 weeks due to continued release of stored hormone
55
What are the adverse effects of thioamides?
Agranulocytosis
56
What is the MOA of high dose iodide?
DEC:
NIS activity
TPO activity
Thyroid hormone release
57
How long does it take before the effects of high dose iodide wear off?
2-3 weeks
58
What is the MOA of levothyroxine?
Replacement T4 (some T3)
59
What are the adverse effects of levothyroxine?
Tachycardia, Afib, angina, insomnia, tremor
Contraindicated with soy
60
How is propranolol used for hyperthyroidism?
Blocks beta1 to decrease cardiac toxicity
Blocks beta2 to decrease tremor
Decreases 5'-deiodinase activity
61
How is lithium used for hyperthyroidism?
inhibits GPCR transduction in the TSH pathway to decrease thyroid hormone secretion, NIS, and TPO
May cause hypothyroidism
62
How is amiodarone used for hyperthyroidism?
Contains iodide = use as source to make hormones
Can cause hyper or hypothyroidism
63
What is goiter?
Swelling of the thyroid gland
64
What is diffuse goiter?
Whole thyroid gland is enlarged due to increased TSH receptor activity
65
What is nodular goiter?
One area of the thyroid gland is enlarged due to tumor of some kind
66
What is hypothyroidism?
Low levels of thyroid hormone
67
What can cause primary hypothyroidism?
thyroid failure
- low iodide intake
- Hashimoto's thyroiditis
- antithyroid meds)
68
What can cause secondary hypothyroidism?
pituitary failure causing low TSH
69
What can cause tertiary hypothyroidism?
hypothalamic failure causing low TRH
70
What are the effects of hypothyroidism?
```
Fatigue,
depression
weakness,
low temp,
cold intolerance,
constipation, bradycardia,
low CO,
decreased DTRs,
dry skin,
brittle hair,
loss of hair,
low glucose,
high LDL,
weight gain,
anemia,
myxedema,
cretinism (not reversible, but preventable)
```
71
Why is hypothyroidism problematic in the elderly?
Symptoms are similar to that of aging
72
How is T4, T3, TSH, goiter, and RAIU seen in very low dietary iodide?
Increased:
TSH
RAIU
Decreased:
T3
T4
Goiter:
diffuse
73
How is T4, T3, TSH, goiter, and RAIU seen in anterior pituitary failure?
```
Decreased:
TSH
T3
T4
RAIU
```
Goiter:
none
74
How is T4, T3, TSH, goiter, and RAIU seen in Hashimoto's thyroiditis?
Increased:
TSH
Decreased:
T3
T4
RAIU
Goiter:
none
75
How can you treat hypothyroidism?
Give T4 (levothyroxine) on empty stomach and avoid soy
76
What happens if you miss a dose of levothyroxine?
It's not good, but the drug has a long-half life so it will not show immediate problem
77
What is hyperthyroidism?
High T3/T4 due to high activity of the thyroid gland
78
What is thyrotoxicosis?
High T3/T4 not necessarily associated with overactive thyroid gland
79
What actions are DECREASED by growth hormone acting at the cytokine receptor?
DEC:
glucose use
insulin
80
Signs of Acromegaly
```
Large hands/feet,
Soft tissue growth
Thickened bones
Sweaty/oily skin
Carpal tunnel
Hyperglycemia
Arthritis
```
81
What increases are seen clinically in growth hormone deficiency?
INC:
Body fat
Normal height in adults
