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Endocrinology Exam 2 > Thyroid Disorders > Flashcards

Thyroid Disorders Flashcards

1
Q

Hypothalamic-Pituitary Thyroid Axis

A
  • Hypothalamus secretes thyroid-releasing hormone (TRH)
  • Pituitary secretes thyroid-stimulating hormone (TSH)
  • TSH stimulates formation of tetraiodothyronine (T4) or “Thyroxine” & some of the formation of triiodothyronine (T3)
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2
Q

2 types of thyroid secretory cells

A

Follicular - produces thyroid hormones
- Thyroxine (T4)
- Triiodothyronine (T3)
Parafollicular (“C cells”) - secretes calcitonin

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3
Q

Under the influence of thyroid stimulating hormone (TSH) _____ is taken into the follicular cell

A

iodide

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4
Q

In the presence of _____, iodide is oxidized (combined with O2) to iodine

A

thyroid peroxidase

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5
Q

Iodine then binds to the ____ portion of the _____ within the colloid of the follicular cell

A

tyrosine; thyroglobulin molecule

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6
Q

Colloid of the follicle stores ____ (~3 months worth)

A

thyroglobulin

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7
Q

T/F thyroglobulin is released with T3 and T4

A

F

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8
Q

> 99% of T3 & T4 entering the blood bind with plasma proteins, mostly to _____

A

thyroxine binding globulin

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9
Q

The unbound 1% of T3/T4 circulating in the blood is

A

Physiologically inactive

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10
Q

Is T3 or T4 more physiologically active?

A

T3

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11
Q

What happens to T4 while circulating

A

T4 is changed in to T3 at the intracellular level by several types of 5’ deiodinase

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12
Q

1/2 life of T3

A

24 hours

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13
Q

1/2 life of T4

A

5-7 days

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14
Q

Thyroid cell prodicing calcitonin

A

Para-follicular cell

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15
Q

Solubility of calcitonin

A

Water Soluble
Peptide hormone travel in the blood & binds on receptor proteins

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16
Q

1/2 life of Calcitonin

A

50-80 min

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17
Q

Four main metabolic functions of T3/T4

A

↑ Basal Metabolic Rate
↑ Cardiac Output
Stimulates BONE maturation & growth
↑ Metabolism

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18
Q

BRAIN Benefits of T3/T4

A

clear thinking, improved mood, & energy

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19
Q

Most common cause of hyperthyroidism

A

Graves Disease

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20
Q

Hyperthyroidism primary causes

A
  • Graves Disease (autoimmune)
  • Subacute thyroiditis ( “DeQuervain” thyroiditis
    Cause = viral infection)
  • ↑ iodine intake
  • ↑intake of exogenous thyroid hormone
  • Drugs (Amiodarone)
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21
Q

Hyperthyroidism secondary causes

A
  • ↑ TSH: Anterior pituitary adenoma
  • ↑ TRH secretion: Hypothalamic tumor
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22
Q

Grave’s Disease (Diffuse Toxic Goiter) is an Autoimmune disorder of the thyroid gland, characterized by ____

A

↑ synthesis & release of thyroid hormones.

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23
Q

Grave’s Disease epidemiology

A

More common in women than men 8:1

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24
Q

Associated with ↑ antibodies, exophthalmos, pretibial myxedema, onycholysis (separation of nail from its bed)
↑ risk other autoimmune disorders

refers to what

A

Graves disease

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25
Q

Subjective complaints (SYMPTOMS) of Graves disease

A

Sweating, weight loss or gain, anxiety, palpitations, loose stools, heat intolerance, irritability, fatigue, weakness, menstrual irregularity

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26
Q

Hyperthyroidism Clinical Presentation of HEENT

A
  • Diffuse non-tender goiter
  • Exophthalmos
  • Proptosis
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27
Q

Clinical Presentation of Hyperthyroidism, CV

A

Arrhythmias ex: atrial fibrillation
↑HR
↑BP

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28
Q

Clinical Presentation of Hyperthyroidism, Neuro

A

Muscle weakness
Sudden paralysis
Resting tremor
Hyperreflexia

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29
Q

Clinical Presentation of Hyperthyroidism, Extremities

A

LE edema
Pretibial myxedema
Fingernail clubbing

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30
Q

Clinical Presentation of Hyperthyroidism, Skin

A

Warm, moist skin
Facial flushing
Pretibial myxedema

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31
Q

What is Pretibial Myxedema (Thyroid Dermopathy) in Hyperthyroidism?

A

Discoloration
shiney pink to purple/brown
Induration- non pitting
“Orange peel”
Deposition of hyaluronic acid

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32
Q

Hyperthyroidism Diagnostic labs

A

↓ TSH (Primary), ↑ TSH (Secondary)
↑ FT4 and T3
Thyrotropin receptor antibodies (TRAb)
Anti-Thyroid peroxidase antibody (Anti-TPOAb) - 75% (MOST COMMON test for autoimmune thyroid disease)

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33
Q

Initially presents as hyperthyroidism but eventually results in hypothyroidism
Can be acute, subacute, or chronic

Describes what

A

Thyroiditis

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34
Q

Subacute Granulomatous thyroiditis in hyperthyroidism

A

“de Quervain’s thyroiditis”
Typically caused by viral infections
- Painful, tender thyroid on physical exam
- Possible prodrome of myalgias, pharyngitis, low-grade fever

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35
Q

Diagnosis for Subacute Granulomatous thyroiditis

A

Physical exam
↑ ESR/CRP
Low or absent anti-TPO antibodies
Mild leukocytosis

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36
Q

Treatment for Subacute Granulomatous thyroiditis

A

NSAIDs for thyroid pain & tenderness
Oral steroids (prednisone) for more severe symptoms

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37
Q

Self-limiting and usually improves or resolve
~ 4-6 weeks
describes what

A

Subacute Granulomatous thyroiditis

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38
Q

Postpartum Subacute Thyroiditis etiology in Hyperthyroidism

A
  • Human chorionic gonadotropin binds to TSH receptors, Causes hyperthyroidism & ↑ serum thyroxine-binding globulin
  • Onset within 12 months after delivery
  • Hyperthyroidism initially → hypothyroidism → euthyroid
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39
Q

Postpartum Subacute Thyroiditis PE

A

painless firm goiter
NO exophthalmos
NO myxedema

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40
Q

Postpartum Subacute Thyroiditis diagnosis

A

↑ anti-TPO titer
autoimmune
Normal ESR/CRP

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41
Q

Postpartum Subacute Thyroiditis treatment

A
  • Symptomatic relief with beta blockers (propranolol beta blocker of choice during breastfeeding)
  • Levothyroxine if symptomatic hypothyroidism, tapered & stopped after 6-9 months
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42
Q

Subclinical Thyroiditis in Hyperthyroidism

A
  • ↓TSH & normal FT4/T3
  • Cause: Over-dosing with thyroid hormone
  • Progression to overt hyperthyroidism
  • Typically reverts to normal within 2 years.
    ↑ risk of atrial fibrillation
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43
Q

Subclinical Thyroiditis treatment

A
  • > 65 yo and those with heart disease or osteoporosis with TSH <0.1
  • Pts with persistently low TSH (<0.1) & asymptomatic
  • Observe pts with TSH 0.1 –0.4 & repeat testing
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44
Q

Temporary symptomatic relief of hyperthyroidism

A
  • β-Adrenergic blockade: Anti–Tachycardia, Tremor, Anxiety & Diaphoresis
  • Artificial tears: exophthalmos
  • Topical glucocorticoids: pretibial myxedema, Anti-inflammatory
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45
Q

Definitive Treatments for Hyperthyroidism

A
  • Antithyroid drugs: Methimazole & Propylthiouracil (PTU)
  • Thyroidectomy
  • Radioactive iodine ablation (RAIA): Good for women planning pregnancy in future
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46
Q

Contraindications (relative) for B-blockers in hyperthyroidism management

A

Asthma or COPD
Raynaud’s
Pregnancy (except labetalol)

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47
Q

Methimazole (Tapazole®) MOA

A

1st line
Inhibits synthesis of thyroid hormone by blocking oxidation of iodine in thyroid gland
blocks synthesis of thyroxine (T4) and triiodothyronine (T3)

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48
Q

Propylthiouracil (PTU) MOA

A

1st line if 1st trimester or breastfeeding
Inhibits synthesis of thyroid hormone by blocking oxidation of iodine in thyroid gland
blocks synthesis of T4 and T3

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49
Q

Indications of Antithyroid drugs/Thionamides

A

Hyperthyroidism
Thyroid storm (adjunct),
Pre-treatment
- Thyroid surgery
- Radioactive iodine treatment

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50
Q

Side effects of Antithyroid drugs/Thionamides

A

Rash
itching
agranulocytosis
pancytopenia
hepatotoxicity
teratogenicity

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51
Q

_____ can be safe in breastfeeding

A

propanalol

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52
Q

Thyroid ablation involves using what ___

A

Radioactive Iodine

53
Q

What does thyroid ablation

A
  • Destroys thyroid tissue
  • No ↑ of subsequent thyroid cancer, leukemia, or other malignancies
54
Q

Contraindications for Radioactive Iodine

A

Pregnancy & lactation
Mothers without childcare

55
Q

Indications for Thyroid ablation

A

Graves
toxic adenoma
multinodular goiter

56
Q

Side effects of thyroid ablation

A

Infertility
N/V
dry mouth

57
Q

Follow-up for Thyroid ablation

A

The resulting hypothyroid state after RAIA requires lifelong thyroid hormone replacement
Monitor for hypoparathyroidism

58
Q

Thyroidectomy indications

A

Graves (total thyroidectomy)
toxic multinodular goiter
thyroid malignancy
large goiters

59
Q

Contraindications for Thyroidectomy

A

comorbidities that influence surgical risk

60
Q

Side Effects of Thyroidectomy

A

Recurrent laryngeal nerve palsy, hoarseness
hypoparathyroidism

61
Q

_____ Usually requires patient be euthyroid prior to surgery

A

Thyroidectomy

62
Q

Thyroid Strom “thyrotoxic crisis”

A

Sudden release of large amounts of thyroid hormone

63
Q

precipitating factors to Thyroid Strom “thyrotoxic crisis”

A

Abrupt stop of anti-thyroid meds
Thyroid surgery
Non-thyroid surgery trauma
Acute infections
Iodinated contrast medium
Burns
Medication SE

64
Q

Symptoms of a Thyroid Storm

A

fever (as high as 104-106°F)
Tachycardia
heart failure
Arrhythmia
Diaphoresis
N/V/D
Irritability, delirium
Seizures, coma
Death (cardiac arrest)

65
Q

PE findings for a thyroid storm

A

Fever
Tachycardia
Goiter
Hand tremors
Moist & warm skin
Hyperreflexia

66
Q

Thyroid Strom “thyrotoxic crisis” Diagnosis

A

High FT4/T3 & low TSH

Others:
Hypercalcemia
Hyperglycemia
abnormal LFTs
↑ or ↓WBC

Imaging: CXR, head CT
EKG: Monitor for arrythmias

67
Q

Thyroid Strom “thyrotoxic crisis” Treatment

A

IV fluid repletion
Supplemental O2
Cooling blankets
Acetaminophen (Tylenol)
Treat precipitating factors
IV Beta-blocker
Loading dose of PTU
Supersaturated potassium iodide (SSKI)
IV steroids

68
Q

Epidemiology of Hypothyroidism

A

> 1% of population
5% over 60 yo

69
Q

PRIMARY CAUSES of Hypothyroidism

A
  • Failure of the thyroid gland (Hashimotos most common, 95%)
  • Iodine deficiency
  • Drugs (Amiodarone, interferon)
  • Iatrogenic
70
Q

SECONDARY CAUSES of Hypothryoidism

A

TSH deficiency
TRH deficiency: Mass lesions, congenital/genetic abnormalities/acquired (concussions), functions (aging/anorexia)

71
Q

HASHIMOTOS THYROIDITIS

A

Autoimmune disease
Patients can frequently have other side effects due to co-occurring autoimmune diseases (Addison disease, hypoparathyroidism, diabetes mellitus)

72
Q

Clinical Presentation of Hypothyroidism

A

Weakness, fatigue, lethargy
Arthralgia’s, carpal tunnel syn.
Cold intolerance, Raynaud’s syndrome
Constipation
weight gain
Depression
Menorrhagia
Headache

73
Q

Objective findings (SIGNS) of Hypothyroidism

A

Bradycardia
Thinning, brittle nails, & hair
Peripheral edema, puffy face & eyelids
Skin pallor or yellowing
Delayed deep tendon reflexes
Palpably enlarged thyroid (GOITER)
hoarseness

74
Q

Two forms of Hypothyroidism

A
  • Goiter
    Hashimoto’s
    Iodine deficiency
    Genetic
    Drugs
  • Atrophic
    Radiation Therapy
    Thyroid agenesis or genetic mutations
    Thyroidectomy
75
Q

Diagnostics for Hypothyroidism

A

TSH - if ↑, thyroid gland is being asked to make more T4
if FT4↓ = primary hypothyroidism
if FT4 normal = subclinical hypothyroidism
If TSH ↓ & FT4 ↓ = secondary hypothyroidism

76
Q

Management of hypothyroidism

A
  • L-thyroxine (Levothyroxine, Levoxyl®, Synthroid®): Synthetic T4
77
Q

Contraindications of L-thyroxine (synthyroid)

A

Drugs that affect GI absorption (adjust dosing time)
Bile acid resins/ sequestrants - cholestyramine, colesevelam
PPIs - omeprazole, pantoprazole
Overt thyrotoxicosis, acute MI, adrenal insufficiency
Not for weight loss or obesity in euthyroid pt

78
Q

Side Effects of L-thyroxine (Levothyroxine, Levoxyl®, Synthroid®)

A

heat intolerance
Tachycardia
arrhythmias/atrial fibrillation elderly
Tremors
weight loss

79
Q

Follow-up for L-thyroxine (Levothyroxine, Levoxyl®, Synthroid®)

A

Target TSH after 4-6 weeks
q6-12 months if at stable dose

80
Q

Desiccated thyroid extract (Armour Thyroid) usage for Hypothyroidism

A

Mostly commonly thyroid hormone from pig thyroid
Ratio of T4:T3 = 4:1
physiologic ratio is 13:1 - 16:1
No strong evidence for desiccated thyroid over monotherapy with levothyroxine

81
Q

Liothyronine (Cytomel®)

A

Synthetic T3
↑ basal metabolic rate
↑ utilization & mobilization of glycogen stores
Promotes gluconeogenesis

82
Q

Side Effects of Liothyronine (Cytomel®)

A

Tachycardia
Hypotension
Slight risk for acute MI

83
Q

is Liothyronine (Cytomel®) safe in pregnancy?

A

Yes, caution in breastfeeding

84
Q

Factors affecting thyroid hormone absorption

A

Age
Malabsorption syndromes
Meds
Weight gain
Pregnancy

85
Q

Life threatening form of hypothyroidism

A

Myxedema Crisis

86
Q

Mortality rate almost 100% without treatment
Mortality rate 20-50% with optimal treatment

describes what

A

Myxedema Crisis

87
Q

Epidemiology of Myxedema Crisis

A

Most common → elderly women who have had a stroke or stopped taking thyroxine medication
Underlying infection, cold exposure, hypoglycemia, hypotension, hypoventilation

88
Q

Severe Adult Hypothyroidism clinical presentation

A

Swelling of the skin & underlying tissues
Waxy consistency: firm & inelastic
Non-pitting edema
Dry skin & hair: frowzy hair
Dull apathetic appearance, swollen lips, thickened nose

89
Q

Severe Adult Hypothyroidis Cause

A

Infections: UTI, pneumonia, influenza
Meds: Amiodarone , narcotics, lithium, not starting thyroid replacement during hospitalization
Trauma, surgery

90
Q

Severe Adult Hypothyroidism: Diagnostics

A

Hypoglycemia
↓ Na+
↓ O2
↓ ventilation
↑ CO2
↑CPK

91
Q

Severe Adult Hypothyroidism management in ICU

A
  • stabilize pts who are hemodynamically unstable
  • focus on repleting fluid & electrolytes
  • IV thyroid replacement (T4 alone) → - oral replacement preferred, if possible
  • Empiric ABX (if indicated)
  • IV hydrocortisone
92
Q

EUTHYROID SICK SYNDROME occurs in ___

A

Pt without known thyroid disease, with ↓ serum FT4 & normal TSH

93
Q

Do not use levothyroxine for ____

A

EUTHYROID SICK SYNDROME

94
Q

Most sensitive test for primary hypo/hyper-thyroidism

A

Thyroid-stimulating hormone (TSH)

95
Q

SINGLE best screening test for HYPOthyroidism

A

Thyroid-stimulating hormone (TSH)

96
Q

More sensitive test for hyperthyroidism

A

Free Triiodothyronine (FT3)

97
Q

Free Thyroxine (FT4) is ___

A

commonly tested along with TSH

98
Q

Presence of _____ is diagnostic for Graves disease

A

Thyroid stimulating immunoglobulin (TSI)

99
Q

Good cancer marker post-thyroidectomy

A

Thyroglobulin

100
Q

Good for Diagnosis & monitoring ofmedullary thyroid carcinoma

A

Calcitonin

101
Q

Anti-thyroid antibody present in Grave’s & Hashimotos Thyroiditis

A

Anti-thyroid peroxidase (TPO) ab

102
Q

Low TSH, Low FT4/FT3

A

Central hypothryroidism

103
Q

High TSH, Low FT4/FT3

A

Primary hypothyroidism

104
Q

Low TSH, High FT4/FT3

A

Primary hyperthyroidism

105
Q

High TSH, High FT4/FT3

A

Secondary hyperthyroidism

106
Q

Imaging test of choice for Thyroid disorder testing

A

Ultrasound

107
Q

_____ is imaging that can help to Confirm cancerous nodule or Graves dz

A

Radioiodine scan

108
Q

Best diagnostic method for thyroid cancer

A

Fine-needle Aspiration (FNA) Biopsy

109
Q

Enlargement of the entire thyroid gland

A

Goiter

110
Q

Single or Multinodular
small round lump(s) from the surrounding tissue on thyroid

A

Nodule

111
Q

Types of Goiters

A
  • Hypothyroid (Hashimoto): Fibrosis, Iodine deficiency overstimulation
  • Hyperthyroid (Graves): Overproduction
  • Subacute: viral infection
112
Q

Types of thyroid nodules

A
  • Non-toxic: No abnormal production of thyroid hormones
  • Toxic: Abnormal production of thyroid hormones
113
Q

Epidemiology of thyroid noduels

A

Common: Palpable nodules in 5% of women & 1% of males.
With the use of CT, MRI, & ultrasound detection rates of incidental nodules has risen to 30-60%.

114
Q

Any nodule ≥___ cm should have Further testing for function & malignancy

A

1

115
Q

Nodules that uptake ____ are rarely malignant

A

RAI

116
Q

____; BEST method to assess a thyroid nodule for malignancy

A

FNA: fine needle aspiration?

117
Q

4 types of Painless swelling in the region of the thyroid (thyroid cancer)

A

Papillary thyroid carcinoma
Follicular (differentiated) thyroid carcinoma
Medullary thyroid carcinoma
Anaplastic thyroid carcinoma

118
Q

Most common thyroid malignancy

A

Papillary Thyroid Carcinoma

119
Q

T/F Follicular Thyroid Carcinoma is generally more aggressive than papillary

A

T

120
Q

Serum calcitonin is elevated in this thyroid cancer

A

Medullary Thyroid Carcinoma

121
Q

Carcinoembryonic antigen (CEA)

A

blood test for cancer

122
Q

Typically presents in older patients as a rapidly enlarging mass in a multinodular goiter.

A

Anaplastic Thyroid Carcinoma

123
Q

Treatment of thyroid cancers

A

Surgical Removal is the treatment of choice for thyroid carcinomas
Post thyroidectomy: patient will need levothyroxine for life

124
Q

Low TSH, Normal FT4/FT3

A

Subclinical Hyperthyroidism

125
Q

High TSH, Normal FT4/FT3

A

Subclinical hypothyroidism

126
Q

Normal TSH, High FT4/FT3

A

Acute psychiatric illness

Drug effect
(amiodarone)

127
Q

Normal TSH, Low FT4/FT3

A

Euthyroid sick syndrome

Drug effect
(amiodarone, interferon…)
Can also be caused by Low TSH, High FT4/FT3

128
Q
A

Endocrinology Exam 2 (4 decks)

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