Thyroid disease Flashcards by Hannah Wilkinson

What does a structural assessment of the thyroid gland involve?

Assessing size of thyroid;
Normal
Reduced or absent
?Ectopic
Enlarged - Goitre
Physiological
Pathological

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What are the physiological reasons for thyroid gland enlargement?

Adolescence
Pregnancy

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What does a functional assessment of the thyroid involve?

Assessing how well it’s functioning;
Euthyroid
Hypothyroid (Underactive)
Hyperthyroid (Thyrotoxic)

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What is the preferred imaging technique for the thyroid?

USS

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When does the foetal thyroid develop and start thyroxine production?

By week 12, thyroxine production by week 16.

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Why is maternal thyroid supply important in a foetus?

Helps neurological development

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Which developmental problems can there be with the thyroid gland?

Congenital hypothyroidism
Aberrant/Ectopic thyroid gland
Thyroglossal cyst

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What does a TFT involve?

Testing for TSH, FT4 and FT3.

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Which hormones are affected in hypothyroidism?

TSH high
FT4 low

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Which hormones are affected in hyperthyroidism?

TSH low
FT4 and FT3 high

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TSH is the initial investigation of choice. When would T4 + T3 be tested?

Secondary/central hypothyroidism
Non-thyroidal illness
Recent treatment for thyrotoxicosis

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Does TSH respond quickly to changes in the thyroid?

No, takes around 6 weeks for levels to be stable when there have been changes to the thyroid.

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What are the normal serum levels for TSH, FT4 and FT3?

TSH - 0.3-3.5 mU/L
FT4 - 10-25 pmol/L
FT3 - 3.5 - 7.5 pmol/L

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What specific symptoms and signs are there of hypothyroidism?

Cold intolerance
Facial puffiness
Dry skin
Hair less
Hoarseness
Heavy menstrual periods
Bradycardia
Stupor or coma

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What risk factors are there for hypothyroidism?

Other autoimmune conditions e.g. T1DM or coeliac
Family history
Immune therapy for cancer - melanoma

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What can happen to the thyroid in postpartum?

Patients can develop postpartum thyroiditis 8-20 weeks postpartum.

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After treatment for which condition can hypothyroidism occur?

Thyrotoxicosis
- if post surgery or post radioiodine

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What is the difference between primary and secondary hypothyroidism?

Primary - high TSH, low T4 + T3. No negative feedback loop to reduce TSH.
Secondary - Low TSH, T4 + T4. Disease of pituitary or hypothalamus.

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Which form of hypothyroidism is rare?

Secondary

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What are the two types of hypothyroidism?

Primary and secondary

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What are some causes of primary hypothyroidism?

Autoimmunity
Infection (thyroiditis)
Drug interactions
Congenital hypothyroidism
Iodine deficiency
Post hyperthyroidism treatment

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What are some causes of secondary hypothyroidism?

Pituitary tumours
Tumours compressing hypothalamus
Sheehan syndrome
TRH resistance
TSH deficiency
Lymphocytic hypophysitis
Radiotherapy

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How is hypothyroidism treated?

Levothyroxine (T4)
Liothyronine (T3) - less commonly. Short half life.

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What is the half life of levothyroxine?

7-10 days

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Why should the elderly generally have a lower dose of levothyroxine?

There is a risk of CCF

When should TSH be tested after starting levothyroxine?

After 4-6 weeks. Keep level around 2 mU/L

If someone is taking levothyroxine, does their dosage change in pregnancy?

Yes - increases by 25-30%

What can happen in severe hypothyroidism?

Myxoedema - Endocrine emergency - high mortality

What are the clinical features of a myxoedema?

Decreased mental status and hypothermia Bradycardia Hypotension Hypoglycaemia Myxoedematous face - peripheral oedema

How is myxoedema treated?

Supportive management - ITU IV levothyroxine + occasionally T3 IV Hydrocortisone 200-400mg daily

What are the specific symptoms of hyperthyroidism?

Weight loss Shakes Palpitations Loose bowels

What are some causes of hyperthyroidism (Thyrotoxicosis)?

Graves disease (autoimmune) Thyroiditis Toxic multi nodular goitre Toxic adenoma Drug induced

Which drugs can cause thyrotoxicosis?

Amiodarone Lithium

Which eye problem can thyrotoxicosis present with?

Thyroid eye disease

Which biochemical changes can be seen in thyrotoxicosis?

Liver - Transaminitis (AST, ALT, ALT) Bone - High ALP, hypercalcaemia Pancytopenia or neutropenia

Why does Graves disease occur?

Autoantibody (Ig) binds to thyroid epithelial cells, mimicking the stimulatory action of TSH. Binds to TSH receptor, and increases thyroid activity. This causes T4 + T3 to increase and the thyroid to grow --> goitre.

What are the symptoms of thyroid eye disease?

Inflammation of orbital tissues (not the eye) Itchy, dry eyes Prominent eyes

What are the signs of thyroid eye disease?

Diplopia/loss of sight Loss of colour vision Redness and swelling of conjunctiva Inability to close eyes Aching and pain behind eyes

What is the name for when eyes are protruding?

Proptosis

What is a toxic adenoma?

Abnormal growth - 'nodule' either solid or fluid filled. Generates excess thyroid hormones. Usually benign.

What is a toxic multi nodular goitre?

Multiple nodules in the thyroid that generates excess thyroid hormones. Usually benign.

What are the five types of thyroiditis?

De Quervain's thyroiditis Postpartum - autoimmune Drug induced - damages thyroid tissue Radiation indued Acute/infectious

What causes De Quervain's thyroiditis?

Viral infection. Painful.

How is hyperthyroidism treated?

Medication - Carbimazole or Propylthiouracil

What can happen is hyperthyroidism is not treated?

Symptoms escalate e.g. Graves disease AF Osteoporosis

What is the MOA of Carbimazole and Propylthiouracil?

Inhibit thyroid peroxidase leading to a reduction of T4 and T3.

How long is the medical treatment of hyperthyroidism usually for?

18-24 months to reduce the risk of relapse

Which dangerous side effect can occur with Thyroid peroxidase inhibitors (Carbimazole and Propylthiouracil)?

Agranulocytosis High mortality, takes 2 weeks to resolve. Sore throat, mouth ulcer and infection.

What two options are there for treating hyperthyroidism with Carbimazole?

Start high then reduce as thyroid function settles Continue high dose then add thyroxine

How does I131 Radiotiodine (RAI) treat hyperthyroidism?

I131 concentrates in thyroid B radiation destroys the cells to make thyroid euthyroid or hypothyroid.

Can a total or sub-total thyroidectomy for hyperthyroidism when a patient is still hyperthyroid?

No - patient needs to be euthyroid first.

What are some risks of a total or sub-total thyroidectomy?

Hypothyroidism Hypoparathyroidism Vocal cord palsy (recurrent laryngeal nerve damage)

How is a thyroid adenoma or multi-toxic goitre treated?

Medical treatment to control thyroid function then curative treatment with I131.

How is thyroid eye disease treated?

To treat thyrotoxicosis; Immunosuppressants Steroids Radiotherapy To treat eye; Orbital decompression Eye surgery

Which rare complication can there be in Grave's disease that has a high mortality risk?

Thyroid storm (thyrotoxic crisis)

What can trigger a thyroid storm?

Surgery Pregnancy Acute severe illness

What are the symptoms of a thyroid storm (thyrotoxic crisis)?

Hyperpyrexia CVS - Tachycardia >140bpm, arrhythmia, HF CNS - Low GCS, agitation, delirium GI - Nausea/vomiting, deranged LFTs

What is the management of a thyroid storm?

Supportive treatment B-blockers for tachycardia Antithyroid medication - Propylthiouracil (PTU) - prevents peripheral conversion of T4 to T3 Iodine solution Steroids and bile acid sequestrant

What are the common causes of goitres?

Hashimoto thyroiditis Graves disease Familial or sporadic multi nodular goitre Iodine deficiency Follicular adenoma Colloid module or cyst Thyroid cancer

What increases the risk of a goitre developing?

Malignancy Family history <20 or >60 Male Radiation exposure

What is involved in the palpation of a thyroid examination?

Hands - erythema hot or cold Face - coarse facies Eyes - exophthalmos Trunk - Proximal myopathy (hyper/hypothyroid) Legs - Pretibial myxoedema (Graves' disease), brisk or slow relaxing reflexes Percussion and auscultation

What dose of Carbimazole is usually given for thyrotoxicosis?

FT4 <30pmol/L - 20mg OD FT4 >30pmol/L - 40mg OD

What are the two types of Auto antibodies?

Destructive - target the thyroid Stimulatory - Target TSH receptor

TPO antibodies increase the risk of developing what in the next 10 years?

Hypothyroidism

Which antibody can cause thyroid diseases?

TSH receptor antibody

Why is surgery not done unless a patient is euthyroid?

Risk of thyroid storm - removing thyroid will release hormones into circulation. CVS risk due of anaesthetic due to increases hormones

Thyroid disease Flashcards

(66 cards)