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Endocrinology > Thyroid > Flashcards

Thyroid Flashcards

1
Q

Radio iodine uptake

Enlarged gland with increased tracer uptake that is distributed homogenously

A

GRAVES DISEASE

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2
Q

Radio iodine uptake

Focal areas of increased uptake with suppressed tracer uptake in the remainder of the gland

A

TOXIC ADENOMAS

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3
Q

Radio iodine uptake

Gland is enlarged with distorted architecture with multiple areas of relatively increased or decreased tracer uptake

A

TOXIC MNG

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4
Q

Radio iodine uptake

Very low Radio iodine uptake due to follicular cell damage and TSH suppression

A

SUBACUTE, VIRAL AND POSTPARTUM THYROIDITIS

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5
Q

Radio iodine uptake

Thyrotoxicosis factitia

A

Associated with low uptake

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6
Q

Thyroid scintigraphy
Functioning or hot nodules
Are they benign or malignant?

A

Almost never malignant

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7
Q

Recommended average daily intake of iodine

Adults

A

150-250 ug/day

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8
Q

Recommended average daily intake of iodine

Children

A

90-120 ug/day

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9
Q

Recommended average daily intake of iodine

Pregnant and lactating women

A

250 ug/day

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10
Q

This protein binds 80% of the thyroid hormones

A

Thyroid hormone binding globulin

Albumin bunds
10% T4 and
30% T3

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11
Q

Deficiency of this mineral may contribute to neurologic manifestations of cretinism

A

Selenium

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12
Q

These drugs suppress TSH

A

Dopamine
Glucocorticoids
Somatostatin

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13
Q

Time for TSH secretion after TRH secretion

A

15 mins

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14
Q

This is characterized by:

  1. Defective organification of iodine
  2. Goiter
  3. Sensorineural deafness
A

Pendred syndrome

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15
Q

There is marked lymphocytic infiltration of the thyroid with germinal center formation

  • atrophy of the thyroid follicles
  • oxtail metaplasia
  • absence of the colloid
  • mild to moderate fibrosis
A

Hashimoto’s thyroiditis

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16
Q

Extensive fibrosis, lymphocytic infiltration less pronounced, thyroid follicles completely absent

This represents the end stage of Hashimotos thyroiditis

A

Atrophic thyroiditis

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17
Q

Account for 50% of

Genetic disease associated with autoimmune hypothyroidism

A
  1. HLA DR polymorphisms
    HLA DR3, DR4, DR5
    2.!CTLA4, a T cell regulatory gene
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18
Q

Composition of thyroid lymphoid infiltrate in autoimmune hypothyroidism

Which PRIMARILY MEDIATES thyroid cell destruction

A

Activated CD4 and CD8 T cells
B cells

CD8 T cells mediate thyroid cell destruction by

1) performing induced cell necrosis
2) granzyme B induced apoptosis

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19
Q

Mechanism of myxedema in hypothyroidism

A

Increased dermal glucosamine glycol content traps water giving rise to skin thickening without pitching

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20
Q

Steroid responsive syndrome associated with TpO antibodies
Myoclonus
Slow wave activity on EEG

A

Hashimotos encephalopathy

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21
Q

Signs and symptoms of other autoimmune disease

Which may be found in autoimmune hypothyroidism

A 
Celiac disease
Dermatitis herpetiformis
Chronic active hepatitis
Rheumatoid arthritis
Systemic lupus erythematosus
Myasthenia Garcia
Sjögren's syndrome
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22
Q

% of patients with autoimmune hypothyroidism where thyroid associated ophthalmopathy is found

A

5%

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23
Q

Goal of treatment in secondary hypothyroidism

A

Maintain T4 levels in the upper half of the reference range

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24
Q

Replacement dose of levothyroxine if there is no residual thyroid function

A

1.6 ug/kg body weight
(100-159 ug)
Taken 30 mins before breakfast

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25
Q

TSH monitoring once full replacement is achieved

A

2-3 yrs

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26
Q

Patient missed a dose levothyroxin e

Skip dose
Or double dose?

A

Double dose. T4 has a long half life

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27
Q

When to treat sub clinical hypothyroidism

A

TSH levels above 10 mIU/L
Symptoms of hypothyroidism
Positive TPO antibodies
(+) evidence of heart disease

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28
Q

Treatment si clinical hypothyroidism and goal

A

Low dose L thyroxine 25-50

Goal: normalize TSH

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29
Q

Idiosyncratic side effect of levothyroxine replacement in children

A

Pseudo tumor cerebri

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30
Q

TSH goals in pregnant women

A
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31
Q

Mortality rate of myxedema coma

A

20-40%

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32
Q

Clinical manifestations of myxedema coma

A

Reduced level of consciousness
Seizures
Hypothermia

Precipitated by:
Drugs
Pneumonia
CHF 
MI 
GI bleeding
CV events
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33
Q

Plays a major role in the pathoenesis of myxedema coma

A

HYPOVENTILATION,

Leading to hypoxia and hypercapnia

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34
Q

State of thyroid hormone excess

A

Thyrotoxicosis

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35
Q

Result of excessive thyroid function

A

Hyperthyroidism

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36
Q

Accounts for 60-80% of thyrotoxicosis

A

Graves’ disease

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37
Q

Almost always arises in the background of Hashimoto’s thyroiditis

A

Lymphoma

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38
Q

Features of thyrotoxicosis may be masked or subtle in the elderly, patients may present mainly with fatigue and weight loss, a condition known as

A

APATHETIC THYROTOXICOSIS

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39
Q

MC cardiovascular manifestation of thyrotoxicosis

A

Sinus tachycardia

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40
Q

Where is thrill or bruit thyroid best detected

A

Inferolateral margins of the thyroid lobes

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41
Q

Cause of lid retraction in Graves

A

Sympathetic overactivity

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42
Q

Earliest manifestation of ophthalmopathy

A

Sensation of grittiness
Eye discomfort
Excess tearing

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43
Q

Measurement of proptosis

A

Exophthalmometer

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44
Q

The most serious ocular manifestation of graves

A

Compression of the optic nerve at the apex of the orbit

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45
Q

Explaining the anatomical localization of immune response in ophthalmopathy

A

Orbital fibroblasts may be sensitive to cytokines

46
Q

Most frequent location of thyroid dermopathy

A

Anterior and lateral aspects of the lower leg

47
Q

Form of clubbing found in

A

Thyroid acropachy

48
Q

Mechanism of action methomazole and ptu

A

Inhibition of the function of TPO, reducing oxidation and organification of iodide

49
Q

FDA indications for the use of PTU over MMT

A

First trimester of pregnancy
Thyroid storm
Minor adverse reactions to methomazole

50
Q

Dose of 131 iodine

A

370 mBq (10 mcI) to 555 mBq (15 mci )

51
Q

Why ptu is the DoC in first trimester of pregnancy, and why shift to MMT later?

A

Aplasia cutis
Choanal atresia

Rare association with hepatotoxicity ?

52
Q

Ratio when converting PTU to MMT in pregnancy

A

15-20 mg PTU to 1 mg MMT

53
Q

PTU dose in thyroid crisis

A

Loading dose 500 to 1000 mg

And 250 every 4 h

54
Q

Rationale iodide in thyroid storm

And why do you give it an hour after PTU dose

A

Block hormone synthesis via wolf chaikoff

Delay: to prevent excess iodine from being incorporated into the new hormone

55
Q

Dose of Potassium iodide in thyroid storm

A

5 drops every 6 hrs

56
Q

Due to suppurative infection of the thyroid

A

Acute thyroiditis

57
Q

MC cause of acute thyroiditis in children and young adults

A

Presence of a pyriform sinus, a remnant of fourth branch mail pouch that connects the oropharynx with thyroid

58
Q

Bacterial causes of thyroiditis

A

Staphylococcus
Streptococcus
Enterobacter

59
Q

Subacute causes of thyroiditis

A

Viral or granulomatosis thyroiditis
Silent thyroiditis , postpartum
Mycobacterial infection
Drug induced (IFN, amiodarone)

60
Q

Also known as:
Granulomatosis thyroiditis
Viral thyroiditis
De quervains thyroiditis

A

Subacute thyroiditis

61
Q

Viruses implicated in subacute thyroiditis

A 
Mumps
Coxsackie
Influenza 
Adenovirus
Echovirus
62
Q

Thyroid shows a characteristic patchy inflammatory infiltrate with disruption of the thyroid follicles and multinucleated giant cells with some follicles

A

Subacute thyroiditis

63
Q

Subacute thyroiditis is a diagnosis often overlooked for this dx:

A

Pharyngitis

64
Q

Complete resolution is usually the outcome in subacute thyroiditis,
what is the % of subacute thyroiditis where permanent hypothyroidism is the outcome

A

15%

65
Q

Three distinct phases over 6 months

A
  1. Thyrotoxic phase
  2. Hypothyroid phase
  3. Recovery phase
66
Q

Compare the T4/T3 ratio of subacute thyroiditis and Graves’ disease or thyroid autonomy

A

Greater T4/T3 ratio in subacute than in graves due to disproportionate increase in T3

67
Q

How to confirm subacute thyroiditis

A

High ESR

Low RAI

68
Q

Rx symptoms of subacute thyroiditis

A

Large doses of aspirin 600 q4-6

If marked:
Prednisone 40-60 mg!

69
Q

Occurs in Px with underlying autoimmune thyroid disease and has a clinical course similar to that of acute thyroiditis

A

Painless thyroiditis/ silent thyroiditis

70
Q

Painless/silent thyroiditis in 5% of women 3-6 mos after pregnancy

(+) TPO antibodies ante partum

A

Post partum thyroiditis

71
Q

Treatment differences subacute thyroiditis and painless thyroiditis

A

Glucocorticoids not indicated in painless thyroiditis

Thyroxine replacement has a role in hypothyroid phase of painless thyroiditis

72
Q

% of patients treated with IFNa who develop drug induced thyroiditis

A

5%

73
Q

Rare disorder occuring in women

Insidious painless goiter with local symptoms due to compression

A

Riedels thyroiditis

74
Q

MC cause of chronic thyroiditis

A

Hashimoto’s

75
Q

The most common hormone pattern in sick euthyroid syndrome

A

Decrease in total and unbound T3 levels (low T3) with normal T4 and TSH
T4 conversion to T3 via perioheral deiodination is impaired —> increased reverse t3)

76
Q

Low T4 syndrome in sick euthyroid syndrome

A

Dramatic fall in t4 and t3

Accelerated expression of type III deiodinase

77
Q

Thyroid hormones

HIV infection

A

Inc t3 and t4

T3 falls with progression to AIDS

78
Q

Thyroid hormones

RENAL DISEASE

A

low T3

Normal rt3 levels

79
Q

Iodine content of amiodarone

A

39% by weight

80
Q

MOA amiodarone induced thyrotoxicosis

A

Amiodarone inhibitors deiodinase activity

Metabolites function as weak agonists of thyroid hormone

81
Q

2 types of AIT

A

Type 1 AIT
+ underlying thyroid abnormality
Inc iodine (jod basedow)

Type 2
No intrinsic thyroid abnormality
Drug induced lysosomal activation

82
Q

Factors that alter thyroid function in pregnancy

A 
Inc HCG doc TSH
Estrogen increase TBG
Immune suppressed 
Placenta metabolizes thyroid hormone
Inc urinary iodide excretion
83
Q

Support Diagnosis of iodine deficiency

A

Low unemployment nary iodine levels

84
Q

Approach to Px
FNAB results

Nondiagnostic

A 
Repeat US guided FNA
            ⬇️
Nondiagnostic?
            ⬇️
Close ff up or surgery

1-5% risk of malignancy

85
Q

Approach to Px
FNAB results

Malignant

A

Pre op US or LN assessment
⬇️
Surgery

97-100% risk of malignancy

86
Q

Approach to Px
FNAB results

Follicular neoplasm

A

Consider molecular testing

Surgery if indicated with pre op US or LN assessment

20-30% risk of malignancy

87
Q

Approach to Px
FNAB results

Atypia or follicular lesion of undetermined significance

A

Repeat US guided FNA or consider molecular testing

88
Q

Risk of malignancy if read as “Benign”

A

2-4% risk

89
Q

Follow up of si clinical hypothyroidism

A

6-12 wks

90
Q

Origin of the word THYROID

A 
THyreos= shield
Eidos= form
91
Q

Where is the thyroid gland located

A

Anterior to the trachea between the cricoid and Suprasternal notch

92
Q

Development of the thyroid gland occurs when

A

3rd week of gestation

93
Q

When does thyroid hormone synthesis begin?

A

11 weeks gestation

94
Q

Give rise to the thyroid medullary C cells

A

Neural crest derivatives from the ultimobranchial body

95
Q

Peak TSsH secretion occurs ___ min after administration of exogenous TRH

A

15 mins

96
Q

Manner of TSH secretion

A

Pulsatile
Highest levels at night
Diurnal rhythm

97
Q

Half life to TSH

A

50 min

98
Q

This is located at the apical surface of the thyroid cells and mediates iodine effluent into the lumen

A

Pendrin

99
Q

Defective organification of iodine, goiter and sensorineural deafness

A

Pendred syndrome

100
Q

Level of urinary iodine in iodine sufficient populations

A

> 10 ug/dL

101
Q

Relative metabolic potency of T4 in comparison to T3

A

T4= 0.3 than of T3

102
Q

When to treat subclinical hypothyroidism if TSH levels are below 10 mIU/L

A

1) symptoms of hypothyroidism
2) positive TPO antibodies
3) evidence of heart disease

103
Q

Treatment of subclinical hypothyroidism

A

25-50 mcg levithyroxine with the goal of normalizing TSH

104
Q

TSH goals during pregnancy in hypothyroidism

A

Increase L thyroxine by 50% in pregnancy
Less than 2.5 mIU/ L during the 1st trimester
3 mIU/L 2nd and 3rd

105
Q

Genetic cause of congenital hypothyroidism
Resistance to TSH
Autosomal dominant

A

Gsa

Albright hereditary osteodystrophy

106
Q

Loss of iodide reutilization

A

Dehalogenase 1 defect

107
Q

Affected in thyroid dysgenesis

A

PAX 8

108
Q

Congenital hypothyroidism

Affected,
THYROID agenesis, choanal atresia, spiky hair

A

TTF- 2

109
Q

Half life of TSH

A

50 mins

110
Q

Graves’ disease with antibthyroid drugs

Maximum remission rates are achieved by ____ months

A

12-18 mos

111
Q

Elderly with CAD increase L thyroxine

A

Every 2-3 months

112
Q

Elderly px versus younger patients dose of thyroxine

A

20% less

Endocrinology (8 decks)

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