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Gen med ends > HPT > Flashcards

HPT Flashcards

1
Q

TSH and T3/T4 in hyperthyroidism

A

TSH is suppressed by high thyroid hormones resulting in low TSH

Exception is pituitary adenoma that secretes TSH in which case it is high

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2
Q

What is primary hyperthyroidism

A

Due to thyroid pathology producing excessive thyroid hormone

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3
Q

What is secondary hyperthyroidism

A

Thyroid is producing excessive thyroid hormone as a result of overstimulation by thyroid stimulating hormone.

The pathology is in the hypothalamus or pituitary.

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4
Q

What is grave’s disease

A

Autoimmune condition where TSH receptor antibodies cause a primary hyperthyroidism.

These TSH receptor antibodies are abnormal antibodies produced by the immune system that mimic TSH and stimulate the TSH receptors on the thyroid

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5
Q

What is the most common cause of hyperthyroidism

A

Grave’s disease

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6
Q

What is a toxic multinodular goitre

A

Condition where nodules develop on the thyroid gland that act independently of the normal feedback system and continuously produce excessive thyroid hormone.

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7
Q

What is exophthalmos

A

Term used to describe bulging of eyeball out of the socket caused by Graves Disease.

This is due to inflammation, swelling and hypertrophy of the tissue behind the eyeball that forces the eyeball forward.

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8
Q

What is pretibial myxoedema

A

Dermatological condition where there are deposits of mucin under the skin on the anterior aspect of the leg (the pre-tibial area). This gives a discoloured, waxy, oedematous appearance to the skin over this area.

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9
Q

What is pretibial myxoedema specific to

A

Specific to Grave’d disease and is a reaction to TSH receptor antibodies

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10
Q

Causes of hyperthyroidism

A

Grave’s disease
Toxic multinodular goitre
Solitary toxic thyroid nodule
Thyroiditis (e.g. De Quervain’s, Hashimoto’s, postpartum and drug-induced thyroiditis)

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11
Q

General features of hyperthyroidism

A 
Anxiety and irritability
Sweating and heat intolerance
Tachycardia
Weight loss
Fatigue
Frequent loose stools
Sexual dysfunction
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12
Q

Features specific to Grave’s disease

A

Diffuse goitre (without nodules)
Graves eye disease
Bilateral exophthalmos
Pretibial myxoedema

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13
Q

Unique features of toxic multi nodular goitre

A

Goitre with firm nodules
Most patients are aged over 50
Second most common cause of thyrotoxicosis (after Grave’s)

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14
Q

What is a solitary toxic thyroid nodule and how are they managed normally

A

where a single abnormal thyroid nodule is acting alone to release thyroid hormone.

The nodules are usually benign adenomas. They are treated with surgical removal of the nodule.

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15
Q

What is de quervain’s thyroiditis

A

Presentation of a viral infection with fever, neck pain and tenderness, dysphagia and features of hyperthyroidism.

There is a hyperthyroid phase followed by a hypothyroid phase as the TSH level falls due to negative feedback.

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16
Q

Management of de quervain’s thyroiditis

A

Self-limiting condition and supportive treatment with NSAIDs for pain and inflammation and beta-blockers for symptomatic relief of hyperthyroidism is usually all that is necessary.

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17
Q

What is a thyroid storm

A

It is also known as “thyrotoxic crisis”. It is a more severe presentation of hyperthyroidism with pyrexia, tachycardia and delirium.

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18
Q

1st line anti-thyroid drug for hyperthyroidism

A

Carbimazole

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19
Q

2nd line anti-thyroid drug for hyperthyroidism

A

Propylthiouracil

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20
Q

Why is carbimazole preferred over propylthiouracil in hyperthyroidism

A

Small risk of severe hepatic reactions

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21
Q

How does radioactive iodine work in hyperthyroidism

A

This is taken up by the thyroid gland and the emitted radiation destroys a proportion of the thyroid cells. This reduction in functioning cells results in a decrease of thyroid hormone production and thus remission from the hyperthyroidism.

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22
Q

What do patients taking radioactive iodine as part of hyperthyroidism treatment require

A

Remission can take 6 months and patients can be left hypothyroid afterwards and require levothyroxine replacement.

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23
Q

Rules for patients taking radioactive iodine

A

Must not be pregnant and are not allowed to get pregnant within 6 months
Must avoid close contact with children and pregnant women for 3 weeks (depending on the dose)
Limit contact with anyone for several days after receiving the dose

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24
Q

Use of beta-blockers in hyperthyrodism

A

Block the adrenalin related symptoms of hyperthyroidism.

Propranolol is a good choice because it non-selectively blocks adrenergic activity

They do not actually treat the underlying problem but control the symptoms whilst the definitive treatment takes time to work. They are particularly useful in patients with thyroid storm.

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25
Q

Definitive management of hyperthyroidism

A

Surgically remove the whole thyroid or toxic nodules. This effectively stops the production of thyroid hormone, however the patient will be left hypothyroid post thyroidectomy and require levothyroxine replacement for life.

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26
Q

Most common cause of hypothyroidism in the developed world

A

Hashimoto’s thyroiditis

27
Q

What is hashimoto’s thyroiditis

A

Caused by autoimmune inflammation of the thyroid gland. It is associated with antithyroid peroxidase (anti-TPO) antibodies and antithyroglobulin antibodies.

Initially it causes a goitre after which there is atrophy of the thyroid gland.

28
Q

Most common cause of hypothyroidism in the developing world

A

Iodine deficiency

29
Q

Medications which can cause hypothyroidism

A

Lithium
Amiodarone(usually causes hypothyroidism but can also cause thyrotoxicosis)

All of the pharmacological treatments for hyperthyroidism have the potential to cause hypothyroidism

30
Q

What is secondary hypothyroidism

A

where the pituitary gland is failing to produce enough TSH. This is often associated with a lack of other pituitary hormones such as ACTH. This is called hypopituitarism

31
Q

Causes of secondary hypothyroidism

A

Tumours
Infection
Vascular (e.g. Sheehan Syndrome)
Radiation

32
Q

Presentation of hypothyroidism

A 
Weight gain
Fatigue
Dry skin
Coarse hair and hair loss
Fluid retention (oedema, pleural effusions, ascites)
Heavy or irregular periods
Constipation
33
Q

What is primary hypothyroidism

A

Caused by thyroid gland insufficiency.

Thyroid hormones (i.e. free T3 and T4) will be low. TSH will be high because there is no negative feedback to the brain, so the pituitary produces lots of TSH to try and get the thyroid working.

34
Q

TSH and T3/T4 in secondary hypothyroidism

A

Both are low

35
Q

Management of hypothyroidism

A

Replacement of thyroid hormone with oral levothyroxine is the treatment of hypothyroidism

36
Q

What is levothyroxine

A

Synthetic T4 which metabolises to T3 in the body

37
Q

Most common type of thyroid tumour

A

Papillary tumour(often young females)

38
Q

Features of papillary carcinoma

A

Mixture of papillary and colloidal filled follicles

Histologically tumour has papillary projections and pale empty nuclei

Seldom encapsulated

Lymph node metastasis predominate
Haematogenous metastasis rare

39
Q

Features of follicular adenoma

A

Usually present as a solitary thyroid nodule

Malignancy can only be excluded on formal histological assessment

40
Q

Features of follicular carcinoma

A

May appear macroscopically encapsulated, microscopically capsular invasion is seen. Without this finding the lesion is a follicular adenoma.

Vascular invasion predominates

Multifocal disease rare

41
Q

Features of medullary carcinoma

A

C cells derived from neural crest and not thyroid tissue

Familial genetic disease accounts for up to 20% cases

Both lymphatic and haematogenous metastasis are recognised, nodal disease is associated with a very poor prognosis.

42
Q

Which blood parameter is often raised in medullary carcinoma

A

Serum calcitonin

43
Q

Features of anaplastic carcinoma

A

Most common in elderly females

Local invasion is a common feature

Can cause pressure symptoms

44
Q

Management of anaplastic carcinoma

A

Treatment is by resection where possible, palliation may be achieved through isthmusectomy and radiotherapy.

Chemotherapy is ineffective.

45
Q

What are thyroid lymphomas associated with

A

Hashimoto’s thyroiditis

46
Q

Management of papillary and follicular cancer

A

Total thyroidectomy
followed by radioiodine (I-131) to kill residual cells

yearly thyroglobulin levels to detect early recurrent disease

47
Q

Which syndrome are medullary thyroid tumours part of

A

MEN-2

48
Q

Which antibodies are usually present in grave’s disease and Hashimoto’s thyroiditis

A

Antithyroid peroxidase(anti-TPO) antibodies which are antibodies against the thyroid gland itself

Antithyroglobulin antibodies

49
Q

In which conditions are antithyroglobulin antibodies present

A

Grave’s disease
Hashimoto’s thyroiditis
Thyroid cancer

50
Q

Limitation of measuring antithyroglobulin antibodies

A

Antithyroglobulin Antibodies are antibodies against thyroglobulin, a protein produced and extensively present in the thyroid gland.

Measuring them is of limited use as they can be present in normal individuals.

51
Q

Purpose of ultrasound in thyroid dysfunction

A

Useful in diagnosing thyroid nodules and distinguishing between cystic (fluid filled) and solid nodules. Ultrasound can also be used to guide biopsy of a thyroid lesion.

52
Q

When are radioisotope thyroid scans used

A

Hyperthyroidism and thyroid cancers

53
Q

What does diffuse high uptake of radioactive iodine indicate

A

Grave’s disease

54
Q

What does focal high uptake of radioactive iodine indicate

A

Toxic multi nodular goitre

Adenomas

55
Q

What do cold areas in radioisotope thyroid scans indicate

A

“Cold” areas (i.e. abnormally low uptake) can indicate thyroid cancer

56
Q

Notable adverse effect of carbimazole

A

Agranulocytosis

57
Q

What is subclinical hypothyroidism

A

TSH raised but T3, T4 normal

no obvious symptoms

58
Q

Significance of subclinical hypothyroidism

A

risk of progressing to overt hypothyroidism

risk increased by the presence of thyroid autoantibodies

59
Q

When should treatment be started for subclinical hypothyroidism

A

start treatment (even if asymptomatic) with levothyroxine if <= 70 years

‘in older people (especially those aged over 80 years) follow a ‘watch and wait’ strategy, generally avoiding hormonal treatment’

60
Q

What is thyroid acropachy

A

Specific graves’ triad of:

digital clubbing

soft tissue swelling of the hands and feet

periosteal new bone formation

61
Q

Contraindications for radio iodine treatment

A

Contraindications include pregnancy (should be avoided for 4-6 months following treatment) and age < 16 years.

Thyroid eye disease is a relative contraindication, as it may worsen the condition

62
Q

What is a branchial cyst

A

Developmental defect of the branchial arches.

The cyst is filled with acellular fluid with cholesterol crystals and encapsulated by stratified squamous epithelium

63
Q

What is myxoedema coma

A

defined as severe hypothyroidism leading to decreased mental status, hypothermia, and other symptoms related to slowing of function in multiple organs

64
Q

Mx of myxoedema coma

A 
IV thyroid replacement
IV fluid
IV corticosteroids (until the possibility of coexisting adrenal insufficiency has been excluded)
electrolyte imbalance correction
sometimes rewarming

Gen med ends (9 decks)

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