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Thyroid Flashcards

1
Q

What is TSH and what does it do?

A

Thyroid-stimulating hormone
Thyrotropin
Glycoproteins produced by the anterior pituitary
Stimulates the thyroid gland

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2
Q

What does the thyroid gland produce

A

Mainly T4 some T3
T3 is 5 fold more active than T4
T4 is activated in the peripheries

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3
Q

How is T3 and 4 transported in the blood

A

Most is bound in the plasma to thyroxine binding globulin

The unbound portion is the active part

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4
Q

What are the action of T3 and 4

A

Inc cell metabolism
Via nuclear receptors
Vital for growth and mental development
They also inc catecholamine affects

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5
Q

What are thyroid hormone abnormalities caused by

A

Usually due to problems in the thyroid itself rarely problems in the hypothalamus or pituitary

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6
Q

Basic thyroid hormone tests

A

Free T3&4

Not total because this is affected by TBG when TBG in so will Total T3&4

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7
Q

When is TBG increased

A

Pregnancy, oestrogen therapy HRT COCP and hepatitis

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8
Q

When is TBG dec

A 
Nephrotic syndrome - protein loss
Malnutrition - protein loss
Drugs- corticosteroids, phenytoin
Chronic liver disease 
Acromegaly
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9
Q

What tests to order when hyperthyroidism in suspected

A

Ask for T3 T4 and TSH

All types have dec TSH except for rare pit secreting adenoma most have raised T4

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10
Q

What tests to order when hypo thyroid suspected

A

Only T4 and TSH
T3 no extra info
Sh varies through the day so try to do it at the same time each day

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11
Q

What is sick euthyroid

A

Any systemic illness TFTs mayb become deranged
Typical pattern is everything low
Tests should be repeated after recovery

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12
Q

Other tests to do in thyroid

A 
Thyroid autoab
TSH receptor Ab
Serum thyroglobulin 
US
Isotope scan
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13
Q

What autoantibodies to do

A

TPO - Antithyroid Peroxidase

Antithroglobulin ab

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14
Q

What is associated with which ab

A

TPO - hashimotos
antithyroglobulin - graves or hashimoto
TSH receptors Ab inc graves

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15
Q

Hat is useful in the tx of carcinoma monitoring

A

Serum thyroglobulin

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16
Q

What is an USS scan used for

A

This distinguishes cystic (usually but not alway benign) from solid (usually malignant) nodules
Can then take FNA from the nodules to determine if it is cancerous and what types of cancer

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17
Q

Types of thyroid cancer

A 
Follicular 
Medullary - c cells so may produce calcitonin may be a part of MEN 2 syndrome - need to perform a phaeochromocytoma screen  
Anaplastic 
Papillary - most common 
Lymphoma
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18
Q

What is an isotope scan used for

A

Iodine or technetium pertechnetate
Useful for determining cause of hyper thyroidism & to detect a retrosternal goitre, ectopic thyroid tissue or thyroid mets (+whole body CT)
If there are suspicious nodules the question is are they hot or cold

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19
Q

Isotope scan hot nodule what does it mean

A

Increased up take is a hot nodule and these aren’t typically malignant

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20
Q

What does a neutral nodule mean on an isotope scan

A

Doesn’t take up anymore radio isotope than any other area on the thyroid
These aren’t typically malignant

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21
Q

What does a cold area mean on an isotope scan of the thyroid

A

The area takes up less radio isotope than the rest of the thyroid
20% of cold nodules are malignant

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22
Q

When is surgery most likely needed on thyroid nodules

A 
Rapid growth 
Compression signs 
Dominant nodule on scintigraphy - dominant nodule on reader of the isotope 
Nodule same or bigger than 3cm
Hypo-echoenicity
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23
Q

What abnormalities should be screened for those with thyroid dysfunction

A 
AF
Hyperlipidaemia
DM
T1DM in1st trimester and post delivery 
Patients on amioderone or lithium 
Patients with Downs or Turners Syndrome
Addison’s disease
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24
Q

What does inc TSH and low T4 mean

A

Hypothyroidism

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25
What is inc TSH and normal T4
Patient doesn’t regularly take their replacement medication | Or subclinical hypothyroidism
26
Inc TSH and inc T4
TSH secreting tumour or thyroid hormone resistance
27
Inc TSH and inc T4 and dec T3
Slow conversion to the active form T4 to T3 Deiodinase deficiency, euthyroid hyperthyroxaemia Thyroid hormone antibody artefact
28
Dec TSH inc T4 and inc T3
Hyperthyroidism
29
Dec TSH and normal T4 and T3
Subclinical hyperthyroidism
30
Dec TSH and dec T4
Central hypothyroidism (hypothalamic or pituitary disorder )
31
Dec TSH dec T4 and T3
Sick euthyroid | Pituitary disease
32
Normal TSH abnormal T4
Consider changes in the thyroid-binding globulin, assay interference, amioderone, pituitary TSH tumour
33
What is thyrotoxicosis
Excess thyroid hormone usually from gland hyperfunction
34
Symptom of thyrotoxicosis
``` Diarrhoea Dec weight Inc appetite Can get paradoxical weight gain in 10% Over active Sweats Heat intolerance Palpitations Tremor Irritability Labile emotions Oligomenorrhoea +/- infertility Rare psychosis, chorea, panic, itch , alopecia, urticaria ```
35
Signs of thyrotoxicosis
``` Inc HR/irregular - AF, SVT, rare VT Warm moist skin Fine tremor Palmar erythema Thin hair Lid lag Lid retraction Potential goitre ```
36
Signs of Graves’ disease
Eye disease - exophthalmos, proptosis, conjunctival oedema, corneal ulceration, papilloedema, loss of colour vision. Pretibial myxoedema - swelling above the lateral malleoli Thyroid acropatchy - clubbing, periosteal action in limb bones
37
Test results in hyperthyroidism
``` Inc T4 and T3 Dec TSH May be mild normocytic anaemia Mild neutropenia Inc ESR Inc ca2+ Inc LFT Check thyroid autoantibodies If cause unclear may want isotope scan Eye disease - ophthalmoscope , visual fields, acuity, eye movements. ```
38
What are the causes of thyrotoxicosis
``` Graves’ disease Toxic multinodular goitre Toxic adenoma Ectopic thyroid gland tissue Exogenous ```
39
What is the most common cause of hyperthyroidism
Graves’ disease
40
What is the prevalence and cause of Graves’ disease
More common in women age 40-60 Cause circulating IgG autoantibodies binding to & activating G-protein coupled thyrotropin receptors which are smooth thyroid enlargement and hormone production particularly T3 and react to orbital autoantigens
41
Triggers of Graves’ disease
Stress Infection Childbirth
42
Are patients always hyperthyroid in graves
Most hyper but can be eu and hypo
43
Is graves associated with autoimmune diseases
Yes Vitiligo T1DM Addisons
44
Who gets toxic nodular goitre
Elderly | Iodine deficient areas
45
What does a toxic multi nodular goitre do
Nodules secrete hormones
46
Tx of toxic multinodular goitre
Tx same as graves If compressive surgery is indicated - dysphagia or dyspnoea
47
What is a toxic adenoma
Solitary nodule producing T3 and T4 On isotope scan hot nodule And the rest of the gland is suppressed
48
What is ectopic thyroid tissue
Metastatic follicular thyroid cancer | Struma overii -ovarian teratoma with thyroid tissue
49
What is subacute de quervains thyroiditis
Self limiting post viral with painful goitre inc temperature +/- inc ESR Tx NSAIDs
50
Tx hyperthyroidism
Drugs Beta blockers - propranolol control rapid symptoms Treat the condition - these drugs are used to decrease thyroid hormone synthesis by acting as a preferred substrate or iodisation by thyroid peroxidase the key enzyme in thyroid hormone synthesis - carbimazole and propyluracil 2 regimens for carbimazole - titrate it up and give carbimazole and Levothyroxine at the same time Prpyluracil is a second line due to the small chance of liver toxicity Surgical - radioiodine tablet Hasn’t been shown to inc risk of cancer Roth defects or infertility in women CI in pregnancy , lactating and you need to be kept further away from children when you have the tx Thyroidectmy usually total risk = damage to recurrent laryngeal nerve = hoarseness and lack of voice Radioidione and thyroidectomy - become hypothyroid so need replacement but is better than potential longterm effects of being hyper and the medication se
51
Complications of hyperthyroidism
``` Heart failure - thyrotoxicosis cardiomyopathy Angina AF Osteoporosis Ophthalmology Gynacomastia Thyroid storm ```
52
What causes thyroid eye disease
Retro orbital inflammation and lymphocyte infiltration resulting in swelling of the orbit
53
What is the main risk factor for thyroid eye disease
Smoking
54
Prevalence of thyroid eye disease
25-50% of those with Graves’ disease
55
Does the eye disease correlate with thyroid disease
May not | The patient could be euthyroid, hypo or hyper
56
How does thyroid eye disease present
It was be the first presenting feature of graves | And can be worsened by tx typically radioiodine but is typically transient
57
Symptoms of thyroid eye disease
``` Eye discomfort Grittiness Inc tear production Photophobia diplopia Dec acuity RAPD - may mean optic nerve compression, depression may be needed get help at once ```
58
Does eye protrusion mean nerve damage
No | If the eye cannot protrude more likely to lead to optic nerve compression
59
Signs of eye disease
Exophthalmos - appearance of protruding eye Proptosis - eye protrude beyond the orbit Conjunctival oedema Corneal ulceration Papilloedema Loss of colour vision Ophthalmoplegia
60
Test for thyroid eye disease
The diagnosis is clinical so none needed | A ct/mri would show enlarged eye muscles
61
Mx of thyroid eye disease
Con - stop smoking Med - symptoms: artificial tears, sunglasses, avoid dust Diplopia - fresnel prism on lens More severe may need high dose steroids Surg - surgical decompression in severe sight threatening conditions eye lid surgery for cosmesis & function Orbital radiotherapy - used to treat ophthalmoplegia Future: anti TNF alpha antibodies - infliximab
62
Causes of goitre
Physiological Graves’ disease Hasimotos thyroiditis Subacute (de Quervain’s thyroiditis) - painful
63
What is the first line treatment in toxic nodular goitre
Radioiodine
64
What happens in the pituitary in Graves’ disease
TSH is suppressed | And the expression of thyrotropin beta subunit
65
What happens to the heart in Graves’ disease
Inc rate Inc contractility Inc serum atrial beta natriuretic peptide
66
What is hypothyroidism
Clinical affect of a lack of thyroid hormone
67
Symptoms of hypothyroidism
Tiredness, sleepy, lethargic, dec mode, cold-disliking,inc weight, constipation, menorrhagia, hoarse voice, dec memory and cognition, myalgia, cramps, weakness
68
Signs of hypothyroidism
``` BRADYCARDIA R = reflexes slow A = ataxia D = dry/thin skin Y = yawning/ tired C = cold hands A = ascites R= round puffy face/double chin D= demeanour - low I = immobile C=CCF ```
69
Diagnosis of hypothyroidism
TFTs Low T4/3 High TSH Rare secondary from pituitary both low
70
Causes of primary autoimmune hypothyroidism
Primary atrophic hypothyroidism = diffuse lymphocytic infiltration of the thyroid, leading to atrophy, no goitre Hashimoto’s thyroiditis = goitre due to lymphocytic and plasma cell infiltration, ab TPO antithyroglobulin high Worldwide = iodine deficiency Post thyroid radioiodine tx or thyroidectomy Drug induced - amioderone, lithium
71
Associations with hypothyroidism
Other autoimmune conditions - Addison’s, T1DM, pernicious anaemia - turners and Down’s syndrome, CF, PBC, ovarian hyper stimulation, POEMS syndrome - poyneuropathy, organomegaly, endocrinopathy, m-protein band (plasmacytoma)+ skin pigmentation/tethering
72
Problems in pregnancy in hypothyroidism
``` Eclampsia Anaemia Prematurity Low birthweight Stillbirth PPH ```
73
Tx hypothyroidism
Young give Levothyroxine and titrate to clinical picture | Elderly give 25 to start and adjust accordingly
74
What does amioderone do to the thyroid gland
It is an iodine rich drug Structural like T4 Hypothyroidism as T4 can be inhibited due to iodine excess Hyperthyroidism can be caused by toxic thyrotoxicosis which causes hormone release Check tft monthly on amioderone If cannot stop amioderone then a thyroidectomy may be needed
75
What is the state before death in hypothyroidism
Myxoedema coma
76
What is subclinical hypothyroidism
TSH >4 Normal T4 and T3 no symptoms Small risk of progression to hypothyroidism This inc the higher the TSH, male, and if you have TPO ab May need treating see if they get any better
77
What Is subclinical hyperthyroidism
TSH low Normal T4/T3 Rule out rare secondary hyperthyroidism - central cause, pregnancy, illness

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