Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Phase 2a - Endocrinology > Thyroid disease > Flashcards

Thyroid disease Flashcards

1
Q

Thyroid disorders

A

Hyperthyroidism 2.5%
Hypothyroidism 5%
Goitre 5-15%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are examples of thyroid autoimmunity?

A

Focal thyroiditis and/or positive TPO and thyroglobulin antibodies
Postpartum thyroiditis
Autoimmune hypothyroidism
- Hashimoto’s thyroiditis
- Atrophic thyroiditis
Graves’ disease
- Thyroid associated ophthalmopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why are autoimmune thyroid diseases important?

A

First autoimmune diseases to be described.

2% of women will get Graves’ disease or autoimmune hypothyroidism (5-10 times the frequency in men).

5% will have postpartum thyroiditis and up to 20% will have positive thyroid antibodies.

Associated with other serious autoimmune disorders.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which are the thyroid autoantibodies?

A

Thyroglobulin and thyroid peroxidase (TPO) antibodies found in almost all patients with autoimmune hypothyroidism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What percent of patients with Graves’ disease also have autoantibodies?

A

75%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Low levels of autoantibodies are also present in which group?

A

Healthy individuals at risk of thyroid or other autoimmune disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mechanisms of thyroid destruction

A

Cytotoxic (CD8+) T cell-mediated

Thyroglobulin and TPO antibodies may cause secondary damage, but alone have no effect

Uncommonly antibodies against the TSH-receptor may block the effects of TSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Graves’ disease

A

One common cause of Hyperthyroidism is Grave’s Disease – an autoimmune condition where antibodies are produced that stimulate the TSH receptors on follicular cells. It affects roughly 1% of the population and is 10 times more common in women than in men.

Patients may present with heat intolerance, weight loss, tachycardia, nervousness, increased sweating, exophthalmos and increased bowel movements. Hyperthyroidism can be treated with Carbimazole which inhibits iodine binding to thyroglobulin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

TSH receptor (TSH-R) antibodies

A

Originally called long acting thyroid stimulators (LATS)

Now called thyroid stimulating antibodies - these are the cause of Graves’ disease

Some TSH-R antibodies do not stimulate the receptor; instead they block the effects of TSH - these (rarely) can cause hypothyroidism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the disease caused when blocking the effects of TSH lead to hypothyroidism?

A

Myxoedema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the predisposition to thyroid autoimmunity?

A

Genetic and environmental factors in varying proportion.

Being female is biggest risk factor, and onset of disease common postpartum.

HLA-DR3 and other immunoregulatory genes contribute (25% monozygotic twins concordant).

Environmental factors include stress, high iodine intake, smoking.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What autoimmune diseases are associated with thyroid autoimmunity?

A
  • Type 1 diabetes mellitus
  • Addison’s disease
  • Pernicious anaemia
  • Vitiligo
  • Alopecia areata
  • Coeliac disease/ dermatitis herpetiformis
  • Chronic active hepatitis
  • Rheumatoid arthritis/ SLE/ Sjogren’s - syndrome
  • Myasthenia gravis (Graves’ disease)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Thyroid associated ophthalmopathy

A

Present in most Graves’ and some autoimmune hypothyroidism patients.

Swelling in extraocular muscles.

Most likely due to an autoantigen in the extraocular muscle that cross reacts with, or is identical to, a thyroid autoantigen

Current favourite candidate is the TSH receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does thyroid associated opthalmopathy occur?

A

GAGs - water trapping - oedema and muscle swelling.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define goitre

A

Palpable and visible thyroid enlargement due to a variety of causes.

Commonly sporadic or autoimmune.

Endemic in iodine deficient areas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe sporadic non-toxic goitre.

A

It is the commonest endocrine disorder.

8.6% prevalence thyroid enlargement.

Euthyroid = normal thyroid function.

Goitre can be diffuse, multinodular, solitary nodule, dominant nodule.

It is important to differentiate benign from malignant.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the three mechanisms of excess thyroid hormone production in hyperthyroidism?

A
  1. Overproduction of thyroid hormone.
  2. Leake of preformed hormone from thyroid.
  3. Ingestion of excess thyroid hormone.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the causes of hyperthyroidism?

A

Graves’ disease (75-80% of cases)

Toxic multinodular goitre

Toxic adenoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

List some of the causes of hyperthyroidism

A

Congenital (neonatal) hyperthyroidism
Non autoimmune hereditary hyperthyroidism
Subacute thyroiditis
Silent thyroiditis
Postpartum thyroiditis
Iodine induced hyperthyroidism
Hyperemesis gravidarum
Molar pregnancy (hCG)
Thyrotoxicosis factitia
Metastatic differentiated thyroid Ca
Struma ovarii
Pituitary resistance to thyroid hormone
Pituitary adenoma (TSHoma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

List some of the drugs that can cause drug induced hyperthyroidism?

A

Iodine
Amiodarone
Lithium
Radiocontrast agents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the clinical features of hyperthyroidism?

A

Weight loss
Tachycardia
Hyperphagia
Anxiety
Tremor
Heat intolerance
Sweating
Diarrhoea
Lid lag and stare
Menstrual disturbance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the specific clinical signs for Graves’ disease?

A

Diffuse goitre
Thyroid eye disease (infiltrative)
Pretibial myxoedema
Acropachy looks similar to clubbing.

23
Q

Investigation of hyperthyroidism

A
  1. Thyroid function tests to confirm biochemical hyperthyroidism.
  2. Diagnosis of underlying cause - important because treatment varies.
  3. Clinical history and physical signs usually sufficient for diagnosis.
  4. Supporting investigations.
24
Q

What would the TFT for primary hyperthyroidism show?

A

Increased T4 and T3 and suppressed TSH in primary hyperthyroidism.

25
Q

What would the TFT for secondary hyperthyroidism show?

A

Increased T4 and increased T3, inappropriately high TSH.

26
Q

What are the supporting investigations

A

TPO
Tg
TRAb
Isotope uptake scan

27
Q

What are the treatment options for hyperthyroidism?

A

Antithyroid drugs (course or long term).

Radioiodine (131 I).

Surgery (partial, subtotal thyroidectomy).

28
Q

Antithyroid drugs

A

Thionamides (i.e. carbimazole, propylthiouracil (PTU), methimazole).

Decrease the synthesis of new thyroid hormone.

29
Q

PTU has an additional effect

A

Inhibits conversion of T4 to T3.

30
Q

Antithyroid drugs do not treat underlying cause but

A

Can have immune modifying effects (decrease in IL-6) and reduction in AB titres.

31
Q

What are the two options for Thionamides?

A

Titration regimen for 12-18 months.

Block and replace regimen (with T4) Suppress everything and replace thyroid hormone.

32
Q

Thionamides can also be given as short- and long-term treatment for

A

Short: render euthyroid before 131 I and surgery.

Long: patients who are unwilling to have above-mentioned treatment.

33
Q

What are the poor prognostic factors for antithyroid drugs?

A

Severe biochemical hyperthyroidism.

Large goitre.

TRAb +ve at end of course of ATD.

Male sex.

Young age of onset.

34
Q

What are the side effects of thionamides?

A

Generally well tolerated.

One common side effect: rash

Less common:
-arthralgia
- hepatitis
- neuritis
- thrombocytopenia
- vasculitis

Occur within first few months - resolves after stopping drug.

35
Q

What is a major side effect of thionamides?

A

Agranulocytosis.

Manifests as sore throat, fever, mouth ulcers.

Warn PT before starting drug.
Stop if symptoms develop and do an FBC.

36
Q

What transports iodine into the thyroid follicular cells?

A

Na/I symporter.

37
Q

131 I

A

One of 20 isotopes of I (127I stable)
Ideal for ablation
Emits large Beta particles of moderate energy
beta particles non penetrating and deliver 90% of energy within a 1-2 mm zone to follicular cells
Some gamma ray emission
Half-life 8.1 days

38
Q

How dose iodine radiation work?

A

Emission of beta particles results in ionization of thyroid cells.

Direct damage to DNA and enzymes.

Indirect damage via free radicals.

39
Q

What are the early effects of 131 I?

A

necrosis follicular cells
vascular occlusion
occur over weeks to months

40
Q

What are the short term effects of 131 I?

A
  • shorter cell survival
  • impaired replication cells
  • atrophy and fibrosis
  • chronic inflammation resembling Hashimoto’s
  • late hypothyroidism
41
Q

What are the indications of 131 I?

A

Graves’ disease
- elective or relapse / failed, medical Tx

Toxic MNG

Toxic adenoma

?? Amiodarone induced thyrotoxicosis type 1

42
Q

Surgery for hyperthyroidism

A

Near total thyroidectomy for Graves’ disease and MNG.

Near total thyroidectomy / lobectomy for toxic adenoma.

43
Q

What are the three types of hypothyroidism?

A

Primary (>99%)
- absence/dysfunction of thyroid gland
- Hashimoto’s thyroiditis

Secondary / tertiary
- pituitary / hypothalamic dysfunction.

44
Q

What are the causes of primary hypothyroidism?

A

Hashimoto’s thyroiditis
131I therapy
Thyroidectomy
Postpartum thyroiditis
Drugs
Thyroiditides
Iodine deficiency
Thyroid hormone resistance

45
Q

What are the causes of secondary/tertiary hypothyroidism?

A

Pituitary disease
Hypothalamic disease

46
Q

What drugs can cause hypothyroidism?

A
  • Iodine, inorganic or organic
    iodide
    iodinated contrast agents
    amiodarone
  • Lithium
  • Thionamides
  • Interferon - alpha
47
Q

What are the causes of hypothyroidism in children and neonates?

A

Neonatal hypothyroidism
Thyroid agenesis
Thyroid ectopia
Thyroid dyshormonogenesis
Others
Resistance to thyroid hormone
Isolated TSH deficiency

48
Q

What are the clinical features of hypothyroidism?

A

Fatigue
Wt gain
Cold intolerance
Constipation
Menstrual disturbance
Muscle cramps
Slow cerebration
Dry, rough skin
Periorbital oedema
Delayed muscle reflexes
Carotenaemia (high carotin levels in blood = yellow)
Oedema

49
Q

Thyroid function test in primary hypothyroidism?

A

High TSH
Low T3 and low T4

T4/ T3 may be low normal in mild hypothyroidism
positive titre of TPO antibodies in Hashimoto’s

50
Q

Thyroid function test in secondary hypothyroidism?

A

TSH inappropriately low
T3 and T4 low

51
Q

What is the treatment of choice for hypothyroidism?

A

Treatment of choice
synthetic L-thyroxine (T4)

Young adults - usual full replacement of 100 microgram - titrate according to TSH

Requirements vary according to cause eg higher doses in thyroid ablation.

Caution in patients with IHD- start lower doses.

52
Q

Monitoring treatment of hypothyroidism?

A

In primary hypothyroidism
dose titrated until TSH normalises
T4 half-life is long - check levels 6-8 weeks after dose adjustment

In secondary / tertiary hypothyroidism
TSH will always be low
T4 is monitored

53
Q

What is monitored in secondary hypothyroidism?

A

T4 because TSH levels are ALWAYS low!

Phase 2a - Endocrinology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions