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Met 3b > Thyroid Improved > Flashcards

Thyroid Improved Flashcards

1
Q

Thyroid hormone control

A

Hypothalamus –> TRH –> pituitary –> TSH –> Thyroids –> T3 and T4

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2
Q

Thyroid negative feedback

A

T3 + 4 negative feedback to pituitary (stop TSH release) and Hypothalamus (stop TRH release)

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3
Q

Thyroid hormone action

A

T4 manufactured in thyroid + deiodinated in periphery to T3
T3 diffuses through cellular membranes
Binds to nuclear thyroid hormone receptor –> effects on gene transcription

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4
Q

Thyroid hormone function

A

Affect:
Basal metabolic rate
Tissue sensitivity to catecholamines
Neural development in the foetus

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5
Q

Hyperthyroidism also known as

A

Thyrotoxicosis

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6
Q

Thyrotoxicosis General symptoms

A

Tired
Anxious
Sweating

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7
Q

Thyrotoxicosis CVS symptoms

A

Palpitations
AF
Heat intolerance

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8
Q

Thyrotoxicosis Abdo symptoms

A

Weight loss
Frequency
Increased appetite

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9
Q

Thyrotoxicosis GU symptoms

A

Oligomenorrhoea

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10
Q

Thyrotoxicosis CNS symptoms

A

Terror
Eye problems
Muscle weakness
Emotional/agitated

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11
Q

Thyrotoxicosis PMH

A

Other autoimmune conditions

IHD

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12
Q

Thyrotoxicosis DH

A

Amiodarone ( contains iodine)
Lithium (mimics iodine)
Interferon
Retrovirals

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13
Q

Thyrotoxicosis FH

A

Autoimmune disease

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14
Q

Thyrotoxicosis ROS

A

Other autoimmune conditions

Onset- acute or insidious?

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15
Q

Thyrotoxicosis Acute onset

A

Graves

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16
Q

Thyrotoxicosis Insidious onset

A

Multinodular Goitre

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17
Q

Thyrotoxicosis + parietal cells

A

Can have gastric parietal cell antibodies –> associated risk of developing pernicious anaemia

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18
Q

Thyrotoxicosis Exam- general

A

Agitated
Thin
Tremor
Vitiligo

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19
Q

Thyrotoxicosis Exam- thyroid

A

Goitre (smooth? (Graves) nodular? (toxic MNG))

Toxic MNG= hyperthyroidism

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20
Q

Thyrotoxicosis Exam- CVS

A

Tachyardia

AF

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21
Q

Thyrotoxicosis Exam- CNS

A

Lid retraction
Lid lag
Brisk reflexes
Proximal myopathy

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22
Q

Thyrotoxicosis Exam- other

A

Signs of Graves- lid lag, lid retraction, ophthalmoplegia, proptosis, pre-tibial myxoedema, acropachy), cardiac failure, high BP, fever

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23
Q

Grave’s disease

A

Thyroid dysfunction in the presence of thyroid stimulating antibodies

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24
Q

Thyrotoxicosis investigation

A

High free T4
Low (undetectable) TSH
Thyroid antibodies to prove thyroid autoimmunity
Gastric parietal cell antibodies
Annual B12 levels to predict onset of pernicious anaemia

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25
Q

Thyrotoxicosis differentials

A 
Grave's
Toxic Multinodular Goitre
Toxic adenoma
Destructive thyroiditis
Excessive iodine (Jod-Basedow)
Drugs
Thyroid hormone Resistance 
TSH producing pituitary tumour - secondary hypothyroidism- raised TSH and FT4
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26
Q

Grave’s disease

A 
Autoimmune disease consisting one or more of:
Thyroid dysfunction
Ophthalmopathy
Pre-tibial myxoedema
Acropachy
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27
Q

Graves thyroid

A 
Diffuse smooth goitre
Bruit
FH
Other autoimmune (T1DM, Addison's, hypoparathyroidism, premature ovarian failure)
Thyroid stimulating antibodies
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28
Q

Graves- Eyes- history + exam

A 
Often smoker
Pain
Tearfulness + grittiness 
Dry
Diplopia
Prior to loss of visual acuity, loss of colour vision
Redness
Proptosis
Lid lag + retraction
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29
Q

Graves Eyes Investigations

A

MRI orbits

TFTs

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30
Q

Graves eyes treatment

A

High dose Steroids
Radiotherapy
Surgery

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31
Q

Thyrotoxicosis treatment

A

Medical
Radioiodine
Surgery

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32
Q

Thyrotoxicosis treatment- medical

A

Graves- 18 months of treatment
Carbimazole
Propylthiouracil
Propanolol non selective BB (reduces acute symptoms as blocks catecholamine sensitive symptoms)

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33
Q

Carbimazole SEs

A

1 in 100 rash

1 in 1000 agranulocytosis- warn about sore throat

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34
Q

Thyrotoxicosis treatment- radioiodine

A 
Iodine 131 radiation- destroys gland
Need to be away from children 2-3 weeks
Can lead to hypothyroidism, so need to take thyroxine
If Graves eyes, can deteriorate
Used when carbimazole fails to cure
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35
Q

Thyrotoxicosis treatment- surgery

A

In presence of large goitre
Need to be on thyroxine for rest of life
Risk of damage to recurrent laryngeal- hoarseness
Risk of damage to parathyroid glands- Vit D

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36
Q

Hypothyroidism history- general

A

Tired
Cold
Dry skin + hair

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37
Q

Hypothyroidism history- Abdo

A

Weight gain

Constipation

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38
Q

Hypothyroidism history- GU

A

Menorrhagia

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39
Q

Hypothyroidism Exam

A 
Puffy
Peaches and cream face
Cold dry skin
Goitre
Bradycardia
Slow relaxing reflexes
In extremis- coma, hypothermia
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40
Q

Hypothyroidism Investigations

A

Low FT4
High TSH
Positive thyroid antibodies (Hashimoto’s)
Cortisol

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41
Q

Cortisol + hypothyroidism

A

If somebody has low Cortisol + ACTH, and give thyroxine to treat hypothyroidism, can precipitate into Addisonian crisis

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42
Q

Hypothyroidism causes

A 
Iodine deficiency (2 billion ppl worldwide)
Hashimoto's thyroiditis
Congenital hypothyroidism (1 in 4000)
Iatrogenic
Post-partum thyroiditis
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43
Q

Hypothyroidism + iodine

A

If give iodine to those that are iodine deficient hypothyroidism, can become rapidly thyrotoxic

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44
Q

CT contrast + hypothyroidism

A

CT contrast is predominally iodine- if give CT contrast to someone with multinodular goitre, very likely to induce thyrotoxicosis

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45
Q

Hypothyroidism treatment

A

Levothyroxine- titrated to target TSH
Titrate to make FT4 within upper half of reference (15-25 pmol/L) range, and TSH in lower half of reference range (0.5-2.5mU/L)

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46
Q

Hypothyroidism treatment consideration

A

Consider cause
How severe
Does patient have co-morbidities

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47
Q

High TSH with normal FT4

A

Intercurrent illness
Inadequate dose
malabsorption
Poor concordance with therapy

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48
Q

Different Thyroid Goitres

A

ANY thyroid enlargement
1) Multi-nodular- more common in low iodine area
2) Secondary to autoimmune overactive or underactive thyroid (Grave’s + Hashimoto)
If it is toxic MNG, due to hyperthyroidism

49
Q

Thyroid MNG History

A 
Lump in neck- how long, has it changed, if sudden onset (bleed), slow onset (NG)
Any thyrotoxicosis symptoms
Dysphagia
Cough/dyspnoea/stridor
Sudden enlargement or pain
50
Q

Thyroid MNG Exam

A

Size
Retrosternal extension (percuss over sternum)
Thyroid status
Signs of airway compromise

51
Q

Thyroid MNG Investigations

A 
TFT
Lung function- tracheal compression
CXR
Ultrasound scan
CT (without scan)
52
Q

Thyroid MNG Treatment

A

Watch + wait
Surgery (thyroidectomy)
Radioiodine (smaller goitre, can cause swelling so don’t do on big one, can reduce 30-50%)

53
Q

Thyroid Neoplasia History

A

Neck lump/swelling

Radiation exposure?

54
Q

Thyroid neoplasia exam

A

Soft/firm/hard

Mobile/tethering

55
Q

Thyroid neoplasia investigation

A

Ultrasound scan +/- fine needle aspiration
Check calcitonin- raised in medullary cancer of thyroid
Chest XR

56
Q

Thyroid neoplasia surgery

A

Diagnostic hemithyroidectomy

Near-total thyroidectomy

57
Q

Thyroid neoplasia Differential

A

Follicular adenoma (non-malignant)
Papillary (lymphatic)
Follicular (blood)
Medullary (linked to multiple endocrine neoplasia type 2)
Anaplastic- poor prognosis
Lymphoma- rare
10 year disease free > 90% for papillary/follicular types

58
Q

Thyroid neoplasia treatment

A

Near-total thyroidectomy helps to confirm histology- whether papillary/follicular cancer
Adjunctive therapy- Iodine 131 ablation
Suppressive thyroid replacement- high dose thyroxine to supress TSH + reduce recurrence
External beam radiotherapy
Serum thyroglobulin useful tumour marker- rising levels = recurrence

59
Q

TBG levels pregnancy

A

Increased (oestrogen inhibits hepatic breakdown)

Still normal T3/4 as increased total

60
Q

TBG in liver failure

A

Decrease

61
Q

TSH effect

A

Increase T3/4
Hypertrophy + hyperplasia of thyroid follicular cells
Increased BF thyroid

62
Q

T3/4 on BMR

A

Increase Na/K ATPase activity to increase O2 production and heat

63
Q

T3/4 on Metabolism

A 
Increased glucose uptake and absorption
Increased glycogenolysis
Increased Gluconeogenesis
Increased insulin
Increased FA oxidation
Decreased cholesterol in plasma
Decreased muscle mass
64
Q

T3/4 on CR

A

Increased HR and CO
Increased vasodilation
Increased ventilation

65
Q

T3/4 on CNS

A

Increase DNS activity

Mental state: hyper- anxiety, nervous, hypo- sluggish

66
Q

T3/4 on skeletal

A

Increased growth plate chondrocytes and osteoblasts

Increase osteoclast activity (in thyrotoxicosis –> osteoporosis)

67
Q

T3/4 on reproductive

A

Thickens endometrium in females

Hypo associated with infertility

68
Q

T3/4 on Development

A

Potentiates growth

Potentiates foetal and neonatal brain development

69
Q

Hypothyroidism

A

High TSH

Low T4

70
Q

Treated hypothyroidism or subclinical hypo

A

High TSH

Negligible T4

71
Q

TSH secreting tumour or thyroid hormone resistance

A

High TSH

High T4

72
Q

Slow conversion of T4 to T3 (deiodinase deficiency; euthyroid hyperthyroxinaemia) or thyroid hormone antibody artefact

A

Low TSH
High T4
Low T3

73
Q

Hyperthyroidism

A

Low TSH

High T4 or 3

74
Q

Subclinical hyperthyroidism

A

Low TSH

Negligible T4 and 3

75
Q

Central hypothyroidism

A

Low TSH

Low T4

76
Q

Sick euthyroidism or pituitary disease

A

Low TSH

Low T4 and 3

77
Q

Toxic adenoma

A

Solitary focal, diffuse hyperplasia of follicular cells

Secrete thyroid hormones

78
Q

Toxic multinodular goitre

A

Most common cause of thyrotoxicosis in iodine-deficient areas
Also seen in elderly patients
Nodules secrete excess thyroid hormones

79
Q

Thyroiditis

A

Hormone synthesis not increase but instead destruction of thyroid follicular cells–> transient increase in thyroid hormones –> once they are ‘exhausted’ the patient becomes hypothyroid

80
Q

Thyroid cysts

A

Benign solitary nodule that creates pressure symptoms

May be painful if bleedsd

81
Q

Hyperthyroidism in pregnancy

A

Increase in thyroid hormones- may trigger Graves
1st half- aggravated
2nd half- ameliorated
Postpartum- recurrence

82
Q

Subclinical Hyperthyroidism

A

Normal T3 and T4 but suppressed TSH
Increases risk of AG
Endogenous causes – toxic adenoma, multinodular goitre
Exogenous causes – levothyroxine

83
Q

Thyroid hormone resistance

A

Mutation in receptor at pituitary- rise in T3 + 4 fails to suppress TSH
Differential- TSHoma

84
Q

MNG relapse

A

Patients with MNG always relapse

85
Q

Hyperthyroidism Management complications

A 
HF
Angina
AF
Osteoporosis
Ophthalmopathy
Gynaecomastia
Thyroid Storm
86
Q

Thyroid storm

A

Rare but life-threatening complication of thyrotoxicosis

It is typically seen in patients with established thyrotoxicosis and is rarely seen as the presenting feature

87
Q

Thyroid storm precipitants

A

Recent thyroid surgery or radioiodine therapy
Infection
MI
Trauma

88
Q

Thyroid storm presentation

A 
Severe hyperthyroidism
Fever
Agitation
Confusion
Coma
Tachycardia
AF
D+V
Goitre
Thyroid Bruit
Acute abdomen
HF
89
Q

Thyroid storm treatment

A

symptomatic treatment e.g. paracetamol
treatment of underlying precipitating event
beta-blockers: typically IV propranolol
Anti-thyroid drughs- carbimazole 15-25mg/6h PO + after 4h give Lugol’s iodine solution 0.3ml/8h PO to block thyroid
Dexamethasone - 15-25mg/6h PO- blocks the conversion of T4 to T3
Treat infection if suspected- co-amoxiclav

90
Q

Thyroid storm treatment aim

A

Counteract peripheral effects of thyroid hormones
Inhibit thyroid hormone synthesis
Treat systemic complications

91
Q

Thyroid storm Treatment continuation

A

After 5 days reduce carbimazole to 15mg/8h PO
After 10 days stop propranolol + Lugol’s iodine and adjust carbimazole
If no significant progress in 24hr, thyroidectomy

92
Q

Thyroid carcinoma- Papillary

A 
70%
Associated with radiation
Young ppl (20-40)
Females
Follicular cell origin
Ig Tumour markers
Spreads- lymphatics, sometimes lung/bone mets
Total thyroidectomy + node excision + radioiodine
Prognosis- good, especially in young
93
Q

Thyroid carcinoma- Follicular

A 
20%
More common females (3:1)
40-60
Origin- follicular cells
Ig Tumour markers
Spread- haematogenous to lung/bone
Treatment- total thyroidectomy + T4 suppression + radioiodine
Prognosis- good if resectable
94
Q

Thyroid carcinoma- Medullary

A 
5%
30% familial (MEN2)
Affects young men 40-50
Origin- parafollicular cells
Tumour markers- CEA + calcitonin
Spread- local + metastases
Treatment- thyroidectomy, node clearance +/- radioiodine
Prognosis- poor, but indolent course
95
Q

Thyroid carcinoma- Anaplastic

A

<5%
Women (3:1), >60yrs
Rapid + aggressive growth + spread
Origin- undifferentiated follicular cells
Spread- locally invasive
Treatment- palliative- can try thyroidectomy +/- radioiodine
V poor prognosis

96
Q

Thyroid carcinoma- Lymphoma

A

2%
In situ autoimmune thyroiditis or systemic lymphoma
Origin- lymphocytes
Treatment- chemo + radio

97
Q

Non-thyroid neck swelling

A 
Thyroglossal cyst
Branchial cyst
Lymphadenopathy
Pharyngeal pouch
Dermoid cyst
Lipoma
Fibroma
Salivary gland swelling
Vascular- carotid body tumour or aneurysm
98
Q

Diffuse Goitre

A

Uniform overall enlargement
Simple euthyroid goitre- pregnancy, puberty
Autoimmune thyroid disease- firm diffuse goitre seen in Hashimoto + Grave
Thyroiditis- acute pain + tenderness in De Quervain’s

99
Q

Nodular goitre

A

Occurs after loss of thyroid structure
Certain areas fibrosed + underactive
MNG
Solitary node- rule out malignancy, normally benign

100
Q

Malignant goitre

A

Adenomas/carcinomas felt as lump

101
Q

Iodine deficiency + goitre

A

Low iodine –> hypothyroidism –> increased TSH –> growth of gland forming diffuse goitre –> some areas fibrose –> multinodular toxic goitre –> hyperthyroidism

102
Q

Iodine excess + goitre

A

high iodine (amiodarone, class 3 antiarrhythmic) –> destructive thyroiditis –> T4 and 3 release –> hyperthyroidism –> may become hypo after few months due to depletion + inhibition of deiodinase by drug

103
Q

Hypothyroidism epidemiology

A

More common than hyper
More common women (6:1)
Excellent prognosis if treated
Untreated –> Heart disease, dementia etc

104
Q

Primary atrophic hypothyroidism

A

Diffuse lymphocytic infiltration of thyroid –> atrophy (no goitre)

105
Q

Hashitoxicosis

A

Rare initial period of hyperthyroid in hashimoto’s thyroiditis

106
Q

Secondary hypothyroidism

A

Not enough TSH due to hypopituitarism

107
Q

Hypothyroidism signs- BRADYCARDIC

A 
Bradycardia
Reflexes relax slowly
Ataxia
Dry thin hair/skin
Yawning/drowsy/coma
Cold
Ascites +/- pitting oedema +/- pericardial or pleural effusion
Round puffy face/double chin/obese
Defeated demeanour
Immobile
CCF
108
Q

Hypothyroidism associations

A 
Autoimmune- T1DM, Addisons, primary aldosteronism, primary biliary cholangitis
Turners and Downs
CF
Ovarian hyperstimulation
POEMS syndrome
Genetic
109
Q

Myxoedema coma- precipitants

A 
Infection
MI
Stroke
Trauma
Thyroidectomy
Radioiodine
Pituitary surgery
110
Q

Myxoedema coma presentation

A 
Looks hypothyroid
Often >65
Hypothermia
Hyporeflexia
Decreased glucose
Bradycardia
Psychosis
Coma
Seizures
111
Q

Myxoedema coma exam

A 
Goitre
Cyanosis
Hypotension
CCF
Sign of precipitants
112
Q

Myxoedema coma treatment

A 
Bloods
ABG for PaO2
Correct hypoglycaemia
Give T 5-30 microg/12h IV slowly
Give hydrocortisone if pituitary hypo suspected
Infection- Abx
fluid caution for heart
Active warming
113
Q

Hypothyroid treatment young patients

A

Levothyroxine 50-100 microg/daily PO before breakfast
Review at 12 weeks
Adjust every 6 weeks
Once normal, check TSH yearly

114
Q

Hypothyroid treatment aim

A

TSH 0.5-2.5mU/L (lower ½ of RR) and free T4 15-25pmol/L (upper ½ of RR)

115
Q

Hypothyroid CIs

A

Enzyme inducer increase levothyroxine metabolism

Iron reduces absorption of levothyroxine, give at least 2 hours apart

116
Q

Hypothyroid treatment elderly + IHD patients

A

 Start with Levothyroxine 25g/daily PO
 Increase dose by 25g/4wks
 Take caution as may precipitate angina or MI

117
Q

hypo + pregnancy treatment

A

increase in dose of 25-50microg is often needed to maintain normal TSH levels

118
Q

Levothyroxine SEs

A

Hyperthyroidism
Decreased bone mineral density
Worsening angina
AF

Met 3b (21 decks)

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