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203: The endocrine system > Thyroid diseases > Flashcards

Flashcards in Thyroid diseases Deck (31)
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1

4 main Thyroid function tests

TSH [most influential]
- Low= hyperthyroidism, secondary hypothyroidism
- High= Primary hypothyroidism

FT3

FT4

Thyroid auto-antibodies

2

Thyroid autoantibodies

Used to measure thyroid functioning.

Examples
- Anti-thyroid peroxidase
- TSH receptor antibody [TRAB]

3

TSH receptor antibodies

Antibodies directed against the TSH receptor
- Can stimulate or block the receptor

Amount is measured to assess function of the thyroid.
- Blocking TRAb= hypothyrodism, such as Hashimoto's
- Stimulating TRAb= Graves'

4

Anti-thyroid peroxidase antibody
- Raise antibodies indicate...

Antibodies that target thyroid peroxidase

Thyroid peroxidase enzyme facilitates the addition of iodine into thyroglobulin.

Raised antibodies indicate
- Graves' disease
- Hashimoto's thyroiditis
- Nodular goitre
- Thyroid carcinoma

5

Causes of hyperthyroidism [6]

Autoimmune [Graves' disease]

Toxic multinodular goitre

Thyroiditis

Toxic adenoma

Pregnancy

Drugs [amiodarone]

6

Hyperthyroidism symptoms [9]

High temperature/ Heat intolerance

Increased appetite

Weight loss

Fatigue

Increased sweating, thirst

Diarrhoea

Oligomenorrhea

Agitation, irritability

Palpitations

Hair loss

7

Hyperthyroidism SIGNS

Tremors

Sweaty, moist skin

Goitre with bruit

Tachycardia, AF

Muscle weakness

Visual defects

Ophthalmoplegia [muscle paralysis around the eye]

8

Graves' disease
- Presentation
- Cause

Presentation
- Most common cause of hyperthyroidism
- Mainly in women, 30-50 yrs
- Thyroid eye disease [20%]
- Goitre with bruit
- Family history of thyroid/ endocrine disease

Cause
- Autoimmune
- TSH receptors are overstimulated in the thyroid [high TSH-receptor antibody].

9

Investigating Graves' disease

Prevalence of thyroid autoantibodies.

Thyroid uptake scan will show diffuse distribution.

Thyroid function results
- Low TSH
- High FT4, FT3

10

Graves' disease medical treatment
- Duration
- Dosage
- Prognosis

18mons- 2yrs
- Carbimazole
- Propylthiouracil

Dosage can start high then get titrated down.
or
Block-replace
- High dose maintained whilst administering thyroxine.

Prognosis
- 1/3 cured
- The rest relapse

11

Radioioidine
- Indication
- Administration
- Risks

Radioactive iodine
- Used to treat hyperthyroidism
- Kills thyroid cells

Administered orally

Risk
- Hypothyroidism
- Close contact with others
- Contraindicated in thyroid eye disease
- Pregnancy [4-6 months wait at least]
- Airport security

12

Sub-total thyroidectomy
- Description
- Risks

Surgery that partial removes the thyroid
- Treats hyperthyroidism [Graves]

Requires medical therapy
- Must be euthyroid before surgery

Risks
- Anaesthetics
- Neck scar
- Hypothyroidism [thyroid hormones given life-long]
- Hypoparathyroidism
- Vocal cord palsy.

13

Gestational hyperthyroidism

Placental beta-human chorionic gonadotrophin [hCG] is released in the first trimester.
- hCG has similiar structure to TSH
- Reduces TSH levels and stimulates thyroid hormone productions

Hyperthyroidism risk increases when
- Pregnant with twins
- Has severe hyperemesis

14

Thyroid eye disease
- Description

Autoimmune condition that targets orbital tissue around the eyes
- Especially extra-ocular muscles.

Mainly associated with Graves' disease
- Confirmatory feature.

15

Thyroid eye disease
- Presentation [7]

Proptosis
- Protrusion of the eyes
- Can cause inability to close eyes and lead to ulcerated corneas

Itchy/ dry eyes

Compression of the optic nerve can lead to colour blindness

Inflammation of the conjuctiva

Eyelid retraction

Periorbital oedema

Diplopia

16

Thyroid eye disease treatment [5]

Smoking cessation

Steroids
- IV methylprednisolone
- Oral prednisolone

Immunosuppressants

Radiotherapy

Surgery
- Relieve compression

17

Toxic adenoma
- Description
- Euthyroidism
- Treatment

Benign tumour of the thyroid that can secrete excess T3
- Causing hyperthyroidism

If euthyroid
- Cancer must be excluded
- Fine needle-aspiration biopsy

Treatment
- Short term medical initially
- Radioiodine

18

Euthyroid goitre

Enlargement of thyroid due to iodine deficiency.

Thyroid enlarges to absorb more iodine.

19

Toxic multi-nodular goitre
- Presentation
- Investigation
- Treatment

Presence of multiple adenomas on the thyroid.
- Nodules can secrete excess thyroid hormones causing hyperthyroidism

Investigation will show thyroid uptake scan with patchy appearance.
- Uptake more [darker] in nodules.

Treatment
- Initially medically, to control symptoms [beta-blockers]
- Curative= radioiodine.

20

Thyroid storm
- Description
- Causes
- Symptoms
- Treatment

A life-threatening increase in thyroid hormone effects.

Causes:
- Incomplete hyperthyroidism treatment.
- Untreated hyperthyroidism

Features:
- High fever
- Arrhythmia, tachycardia
- Vomiting, diarrhoea

Treatment
- Ionorganic iodine
- Anti-thyroid drugs [carbimazole, propylthiouracil]
- Beta blockers
- IV fluids

21

Triggers of thyroid storm [7]

Acute/ severe illness/ infection

Hypoglycaemia

Childbirth

Burns

MI, PE

Surgery

Diabetic ketoacidosis

22

Conditions associated with thyroid disease
- Autoimmune [5]
- Syndromes
- Drugs

Other autoimmune conditions
- T1 diabetes
- Pernicious anaemia
- Addison's disease [hypoadrenalism]
- Premature ovarian failure
- Coeliac disease

Syndromes
- Turner's
- Down's

Drugs
- Lithium
- Amiodarone

23

Hypothyroidism
- Symptoms [8]

Lethargy

Weight gain [despite no change in diet and physical activity]

Cold intolerance

Constipation

Dry skin

Heavy periods

Hair loss

Puffy face

24

Hypothyroidism
- Signs [8]

Periorbital oedema

Flaking skin

Diffuse hair loss

Goitre

Carpel tunnel [compression of the median nerve]

Delayed reflex

Bradycardia

Effusions [severe]

25

Primary hypothyroidism
- Causes

Autoimmune
- attack on thyroid gland.

Iodine deficiency

Drugs
- Lithium

Thyroiditis

Congenital

26

Autoimmune primary hypothyroidism
- Description

Most common cause of hypothyroidism.

Autoantibodies block TSH receptors
- Also inhibits peroxidase


- Reduced FT4, FT3, high levels of TSH.

27

Hashimoto's disease

Primary autoimmune hypothyroidism with the presence of goitre
- Contain lymphocytic infiltration

28

Primary myxoedema

Autoimmune hypothyroidism without goitre or lymphocytic infiltration.

Caused by accumulation of glycosaminoglycans in interstitial.

Very severe, can lead to death/ coma

29

Thyroiditis

Self-limiting thyroid disease characterised by initial hyperthyroidism then hypothyroidism.

Initial hyperthyroidism
- Lasts 1-2months
- Does not respond to anti-thyroid drugs
- Cold isotope scan [uptake reduced]


Longer hypothyroid phase
- 4-6 months
- Mostly normal within a year

30

Thyroiditis high risk populations

Pregnant/ 1 year post-partum

Tender thyroid

Thyroid on inspection does not fit lab results

Recent hepatitis C treatment with interferon