L6: Thyroid Disorders Flashcards
(131 cards)
1
Q
T4 has four ____ while T3 has three
A
Iodine residues
2
Q
T4 means
A
Tetraiodothyronine or L-thyroxine
3
Q
T3 means
A
L-triiodothyronine
4
Q
glycoprotein synthesized
in the thyroid follicular cell, and acts as a precursor for the synthesis of thyroid
hormones
A
Thyroglobulin
5
Q
Thyroglobulin contains large amount of ?
A
Tyrosine
6
Q
Iodine from food is transported to the plasma and to the thyroid follicular cell. This process is called as?
A
Iodine trapping
7
Q
Enzyme needed to activate inorganic iodide
A
thyroid oxidase or
peroxidase
8
Q
Once activated, iodine will be transported
here, where it will be used for the
organification of thyroglobulin.
A
follicular lumen
9
Q
iodine will be covalently
linked to the tyrosine residues located in
thyroglobulin
A
Organification
10
Q
Organification forms iodotyrosine residues
A
DIT – diiodotyrosine (2 iodine
residues connected to tyrosine)
MIT – monoiodotyrosine (1 iodine)
11
Q
will combine to form T4
A
DIT + DIT
12
Q
will combine to form T3
A
DIT + MIT
13
Q
Stimulates the release of thyroid hormones from thyroglobulin
A
Lysosomes
14
Q
more abundant in the plasma; less
biologically active
A
T4
15
Q
less abundant in the plasma; more
biologically active (acts on the peripheral
tissues)
A
T3
16
Q
T4 can be converted into T3
through the process of
A
Deiodination
17
Q
In deiodination, T4 can also be converted into?
A
Reverse T3
18
Q
block transport of
iodide into the thyroid gland
A
Bromine, Fluroine, Lithium
19
Q
These substances can impair
organification and coupling reaction
A
Amides (thionamides, sulfonamide,
salicylammide) and Antipyrine (an antipyretic)
20
Q
Inhibit secretion of thyroid hormone
A
large doses of iodide and
lithium
21
Q
The release of thyroid hormones is regulated by
the
A
hypothalamic, pituitary, and thyroid axis or the
HPT axis.
22
Q
The primary point of regulation for this axis occurs
at the release of the _ by _
A
TSH by the anterior pituitary gland
23
Q
Release of TSH is stimulated by the
release of the _ by _
A
TRH by the hypothalamus
24
Q
TSH receptor is also called as?
A
Thyrotropin receptor
25
Activating TSH receptor activates what
activate adenylyl
cyclase, converting ATP into cAMP
26
An increased level of this increases the expression of the gene involved in the synthesis of thyroid hormones
cAMP
27
negative feedback control
mechanism
Once the body detects that the level of
thyroid hormones is too high, it will send a
negative feedback signal to the **pituitary
gland, preventing release of TSH**
28
test used
to measure how much radioactive iodine is
taken up by the thyroid gland.
RAIU (Radioactive Iodine Uptake)
29
THYROTOXICOSIS WITH
HYPERTHYROIDISM has high _
RAIU
30
THYROTOXICOSIS W/O HYPERTHYROIDISM has __ RAUI
31
One of the most common cause of
hyperthyroidism
GRAVE’S DISEASE
32
Immune system disorder resulting from
overproduction of thyroid hormones
GRAVE’S DISEASE
33
Thyroid-stimulating antibodies (TSAb)
directed against the thyrotropin receptor on the
surface of the thyroid cell.
Graves disease
34
Also known as **Plummer’s disease**
Toxic multinodular goiter
35
enlarged thyroid gland
Goiter
36
TH production is independent of TSH
Toxic multinodular goiter
37
Benign tumor that may be
active or inactive
Thyroid adenoma
38
Active tumor
Toxic adenoma
39
Function is independent of pituitary control
Thyroid adenoma
40
↑Human chorionic gonadotropin (hCG) → TSH
receptor → TH
Trophoblastic disease
41
Serum hCG levels usually exceed ____ U/mL
(kU/L) and always exceed ___ U/mL
300
100
42
Mean peak hCG level in Normal pregnancy:
50
U/mL
43
↑ or inappropriately “normal” serum
immunoreactive TSH concentrations
TSH-INDUCED HYPERTHYROIDISM
44
Evidence of peripheral hypermetabolism
TSH-INDUCED HYPERTHYROIDISM
45
Diffuse thyroid gland enlargement (goiter)
TSH-INDUCED HYPERTHYROIDISM
46
Characterized by the presence of tumors in the
anterior pituitary gland
TSH-SECRETING PITUITARY TUMORS
47
Tumors can secrete a TSH that is as biologically
active as the normal TSH, that is unresponsive
to normal feedback control.
TSH-SECRETING PITUITARY TUMORS
48
TSH-SECRETING PITUITARY TUMORS cosecretes what
prolactin and growth hormone
49
Prolactin cause
Amenorrhea/galactorrhea
50
Growth hormone causes
Signs of acromegaly
51
Selective resistance of the pituitary thyrotrophs to
thyroid hormone → ↑TSH → Hyperthyroidism
PITUITARY RESISTANCE TO THYROID
HORMONE
52
Thyrotoxicosis factitia
EXOGENOUS THYROID HORMONE
53
a physiological response where the thyroid gland temporarily reduces thyroid hormone synthesis in the presence of high iodine levels
Wolf-chaikoff effect
54
Thyroid tissue destruction, inflammation,
fibrosis
Type II-amiodarone induced thyrotoxicosis
55
↑Iodine delivery and uptake → ↑TH
Type I-amiodarone induced thyrotoxicosis
56
Common cause of thyrotoxicosis
PAINLESS THYROIDITIS
57
Autoimmunity underlies most cases
PAINLESS THYROIDITIS
58
Inflammation is caused by presence of anti-
thyroid antibodies that attack thyroid tissue
Painless thyroiditis
59
Is thyroid tenderness present in painless thyroiditis
No
(absent)
60
Similar to painless thyroiditis, except
inflammation is caused by a virus
Subacute thyroiditis
61
Patients complain of severe pain in the thyroid
region, which often extends to the ear on the
affected side
SUBACUTE THYROIDITIS
62
Teratoma of the ovary that contains differentiated
thyroid follicular cells and is capable of making
thyroid hormone.
STRUMA OVARII
63
Functioning metastatic differentiated papillary or
follicular carcinomas synthesize sufficient thyroid
hormones → thyrotoxicosis.
METASTATIC THYROID CANCER
64
Outstretched hands
hyperkinesia
65
Hyperactive deep tendon reflexes
hyperreflexia
66
unique sign of grave’s disease
Exophthalmos
67
swelling or redness of legs, especially in
the pretibial area or shin
Pretibial myxedema or thyroid dermopathy
68
Pretibial myxedema or thyroid dermopath is due to localized accumulation of?
hyaluronic acid and chondroitin sulfate in
the dermis of the skin
69
Sign of autoimmune disorder,
characterized by digital clubbing, swelling
of hands and feet
Thyroid acropachy
70
When you feel up the patient’s neck, you
will feel vibrations
Thyroid thrill and systolic bruit
71
Give false positive result in blood tests for diagnosing hyperthyroidism and thyrotoxicosis
Biotin
72
Normal RAIU
1p-30%
73
Black thyroid scan
Grave’s disease
74
Patchy white thyroid scan
Thyroiditis
75
Single black patch in thyroid scan
Hot nodule
76
Single white patch in thyroid scan
Cold nodule
77
Two types of thyroidectomy:
Total and subtotal
78
Thyroidectomy for graves disease
Total thyroidectomy
79
Indication for thyroidectomy
o Large thyroid gland (>80 g)
o Severe ophthalmopathy
o Lack of remission on antithyroid drug
80
Before conducting thyroidectomy, you
need to ensure that the patient is in _
Euthyroid state
81
given until the
patient is euthyroid (6-8 weeks) b4 thyroidectomy
Methimazole
82
given 10-14 days before surgery before thyroidectomy
Iodides 500 mg/day
83
given 10-14 days
combined pretreatment with propranolol before thyroidectomy
Potassium iodide
84
given several weeks
preoperatively and 7-10 days after
surgery. To maintain PR <90 bpm
Propranolol
85
Thionamide drugs
• Methimazole (MMI)
• Propylthiouracil (PTU)
86
PTU acts on the peripheral tissues,
preventing conversion of T4 into T3
Propylthiouracil
87
Inhibits peroxidase, which is responsible
for the oxidation of iodide into iodine
Thionamides
88
Can also inhibit coupling reactions of
iodotyrosine residues, which prevents
synthesis of thyroid hormones
Thionamides
89
Which thioanamide is more potent
Methimazole
90
safest thionamide for
pregnant patients in the 1st trimester
ONLY
Propylthiouracil
91
To induce long-term remission in
patients with Grave’s disease →
Continue antithyroid therapy for ___
12 - 24 mos
92
After remission monitor the patient every ___
6 to 12 mos
93
Tx when relapse occurs while using thionamides
Alternate therapy with RAI
94
Minor ADRs of thionamides
- pruritic maculopapular rashes
- arthralgia or joint pain
- fever
- benign transient leukopenia
95
When should u discontinue thionamides when it causes benign transient leukopenia
Since leukopenia is transient and if the WBC is not too low, you may continue the drug. Continue to
monitor, and if **WBC continues to lower**, it becomes reasonable to discontinue.
96
Major ADRs of thionamides
- agranulocytosis
- a plastic anemia
- arthralgia and lupus-like syndrome
- Polymyositis
- GI intolerance
- hypoprothrombinemiamia
- hepatotoxicity
97
Inhibit thyroid hormone biosynthesis by
interfering with intrathyroidal iodide
utilization
Iodides
98
Decrease the size and vascularity of the
gland
Iodide
99
Difference in improvement seen in thionamides and iodides
Thionamides - 4-8weeks
Iodides - 2-7 days
100
Adjunctive therapy to prepare patients
with Grave’s disease for surgery
(euthyroid state)
Iodides
101
Adrs of iodides
- hypersensitivity reactions
- salivary gland swelling
- iodism
- gynecomastia
102
1. Contains 38 mg iodide per drop
2. Contains 6.3 mg iodide per drop
1. Saturated solution of potassium iodide
2. Lugol’s solution
103
How many days is needed to prevent
interference of iodides with the
uptake of RAI
3 to 7 days
104
Used to ameliorate the symptoms such as
palpitations, tremors, anxiety, and heat
intolerance
B - blockers
105
block the conversion
of T4 to T3
Propranolol and Nadolol
106
Adjunctive therapy with antithyroid drugs,
RAI, or iodides in Grave’s disease and toxic nodules, in preparation for surgery, in
thyroid storm
Beta blockers
107
CI of beta blockers
o Decompensated heart failure
o Sinus bradycardia
o Concomitant therapy with MAOI/TCA
o Hypoglycemia
108
Initial dose of propranolol
Initial dose: **20-40 mg QID**
109
Dose of propranolol for younger and severely toxic patients
** 240-480 mg/day**
110
Useful when contraindications to B-blocker exist
Centrally acting sympatholytics
111
For symptomatic treatment of hyperthyroidism
Centrally acting sympatholytics
112
Dose of clonidine
150 mcg twice daily
113
Diltiazem dose
120 mg every 8 hours
114
Agent of choice for Graves’ disease, toxic
autonomous nodules, and toxic MNGs.
SODIUM IODIDE 131 (131I)
115
mainstay adjunctive therapy to RAI
treatment.
b-blockers
116
given prior to RAI to patients with
cardiac disease and elderly
thionamides
117
thionamides should be withdrawn in __ days prior to RAI and reinstituted _ days after
4-6 days
4
118
increases cure rate and shortens time to cure
lithium
119
prevents post-therapy increase in thyroid hormones
lithium
120
has the same indication as thionamides
lithium
121
side effects of iodides
o Hypothyroidism (occurs years after RAI)
o Mild thyroidal tenderness
o Dysphagia
122
Preferred thionamide
propylthiouracil
123
does NOT have an effect on
the peripheral tissues (but has a longer
duration of action)
methimazole
124
can propylthiouracil be crushed into suspension with water or saline and be instilled via gastric or rectal tube
yes
125
Should be administered after thionamide is
initiated
iodide
126
Can be used in patients with pulmonary
disease (COPD or asthma) or at risk for
cardiac failure
esmolol
127
why are corticosteroids used for thyroid disorders
Benefits derived from steroids may be caused by
their **antipyretic action** and their effect of
**stabilizing BP**
128
should not be given
aspirin or NSAIDS
129
given to remove excess thyroid hormone
PLASMAPHERESIS & PERITONEAL
DIALYSIS
130
131
