Clinical Thyroid Disease Flashcards by Sophie Pitcairn

What are some symptoms of hypothyroidism?

Fatigue/lethargy, cold tolerance, weight gain, non specific weakness, constipation, menstrual irregularities, depression, dry skin, and thyroid pain

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What are some signs of hypothyroidism?

Coarse dry hair/skin, oedema (including eyelids), vocal changes, goitre, bradycardia, delayed reaction of deep tendon reflexes and paraesthesia

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What do hypothyroid symptoms overlap with?

Euthyroid symptoms

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What tests should be done for hypothyroidism?

Check TFTs - TSH and free T4
Consider also checking FBC and glucose/ HbA1c

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What are the typical results of hypothyroidism?

FT3/4 decreased
TSH increased

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What should a patient with hypothyroidism be started on?

Start Levothyroxine at 1.6 micrograms per Kg daily
If over 65 or cardiac disease then 25 to 50 micrograms a day
Measure TFTs every 3 months until TSH has stabilised
Also test thyroid peroxidase antibodies

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How should Levothyroxine be taken?

Taken first thing in the morning and swallowed with water on an empty stomach
Also start on high dose

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What are the key points of hypothyroidism?

Weight gain, lethargy, feeling cold, constipation, heavy periods, dry skin/hair, bradycardia, slow reflexes, goitre and severe puffy face

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What are the key points of hyperthyroidism?

Weight loss, anxiety, heat intolerance, bowel frequency, light periods, sweaty palms, palpitations, hyperreflexia, tremors, goitre and thyroid eye symptoms

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What is the prevalence of hypothyroidism?

Commonest endocrine condition after diabetes
Can also have subclinical hypothyroidism

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What are some congenital causes for primary hypothyroidism?

Developmental - agenesis/ maldevelopment
Dyshormonogenesis - trapping/ organification of iodine
All babies screened at birth

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What are some acquired causes of primary hypothyroidism?

Autoimmune thyroid disease - Hashimoto’s
Iatrogenic - post op, post radiotherapy, anti-thyroid drugs
Chronic iodine deficiency
Post subacute thyroiditis

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What are some causes of secondary/ tertiary hypothyroidism?

Pituitary/ hypothalamic damage -
Pituitary damage, craniopharyngioma, and post pituitary surgery/ radiotherapy

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What are the typical results of subclinical hypothyroidism?

Normal FT3/4
Increased TSH - working harder to control the normal range of T4

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How should subclinical hypothyroidism be treated?

TFTs and thyroid peroxidase antibodies test
If more than 10mU/L treat like overt hypothyroidism
Or if symptoms trial medication
If not then monitoring

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What are some alternative causes for hypothyroid symptoms?

DM, adrenal problems, hypopituitarism, coeliac, anaemia, hypercalcaemia, BB, statins, opioids, chronic liver or kidney disease, obesity, and stress

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Describe thyroid pregnancy and how medication would change

Adequate preconception replacement
Empirical dose increase in early pregnancy
Regular monitoring
Aim is for TSH in lower half of normal range
Post natal - reduce levothyroxine to pre-pregnancy dose and re check

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What percentage of treated hypothyroid patients have subclinical hyperthyroidism?

20%

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What are the risks of overtreatment for hypothyroidism?

AF and osteopenia/ fracture

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What are the typical test results of hyperthyroidism?

Increased FT3/4
Reduced TSH

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What is the typical test results of subclinical hyperthyroidism?

Normal FT3/4
Reduced TSH

What are the primary causes of thyrotoxicosis (hyperthyroidism)?

Grave’s disease
Toxic multinodular goitre
Toxic adenoma

What are the secondary causes of thyrotoxicosis?

Pituitary adenoma secreting TSH

What are some causes of thyrotoxicosis without hyperthyroidism?

Destructive thyroiditis - post-partum and subacute Quervain’s
Excessive thyroxine administration

Describe Grave's disease

70-80% of hyperthyroidism cases More females Autoimmune driven - thyroid peroxidase antibodies, TSH receptor antibodies which stimulate thyroid to produce more TH

How is Grave's disease diagnosed?

Hyperthyroidism Thyroid antibodies - TSH receptor antibodies Symptoms and signs - thyroid eye disease, goitre, acropachy...

Describe multi-nodular goitre

Most common cause of thyrotoxicosis in elderly Goitre and absence of Grave's Will not go into spontaneous remission

Describe subacute (de Quervain's) thyroiditis

Generally younger patients <50 Viral trigger Often recall painful goitre and possible fever/ myalgia and ESR elevated May require short term steroids and NSAIDs

What is used for management of hyperthyroidism?

Radio-iodine therapy Anti-thyroid drugs Surgery BBs for tremor, tachycardias and palpitations

What are the anti-thyroid drugs used?

Carbimazole Propylthiouracil - more side effects Can use titration regimen or block then replace (more side effects) Both can cause hypothyroidism and 50% cure

What are the side effects to anti-thyroid drugs?

Both can cause agranulocytosis Propylthiouracil - rash Both hypothyroidism

When is long term dose of ATD used?

Elderly Cardiac complications Unwilling for RAI

Describe radio-iodine therapy

Definitive treatment High dose ablation had most cure rate but more chance of hypothyroidism Compared to variable calculated but less cure and hypothyroidism May need steroids

When is RAI avoided?

In severe eye disease

Describe subclinical hyperthyroidism

TSH supressed but normal free TH Concerns if bone density is decreased postmenopausal and AF Treatment - ATD/ RAI if persistent esp. if older and risk of cardiac risk

What are the typical results of secondary hypothyroidism?

FT3/4 decreased TSH normal or low

What is the results of resistance to thyroid hormone (TSHoma)?

Increased FT3/4 Normal or increased TSH

What are some causes for goitre?

Puberty, pregnancy, Grave's, Hashimoto's, acute thyroiditis, chronic fibrotic thyroiditis, iodine deficiency, dyshormogenesis and goitrogens

What are the different types of goitre?

Multinodular goitre, diffuse (colloid or simple), cysts, tumours and miscellaneous - sarcoidosis and TB

Describe a solitary nodule thyroid

Risk of malignancy - child, adults between 30-60, previous head/ neck irradiation and cervical lymphadenopathy 5% chance of malignancy

What are the investigations for solitary thyroid nodule?

Thyroid function tests Then US Then fine needle aspirations - Thy1 inadequate Thy2 benign Thy5 cancer

Describe thyroid cancer incidence

Most common endocrine malignancy Lowe mortality than most cancers

What are the types of differentiated thyroid cancer?

Papillary and Follicular

Describe papillary thyroid cancer

Commonest Multifocal and local spread to lymph nodes Good prognosis

Describe follicular thyroid cancer

Usually single lesion Metastases to lung/ bone Good prognosis if resectable

When is prognosis poorer for thyroid cancer?

If age less than 16 or more than 55 Tumour bigger than 4cm Spread outside thyroid capsule and metastasised TMN staging

Explain thyroid cancer management

Near total thyroidectomy High dose radio-iodine Long term suppressible doses of thyroxine Follow up - thyroglobulin marker Whole body iodine scanning and dynamic risk stratification

What increases the likelihood of giving radio-iodine?

Bigger tumours, multifocal, invasion, adverse histology and large lymph nodes

Describe anaplasic thyroid cancer

Less than 5% of thyroid cancers Aggressive and locally invade Very poor prognosis as does not respond radio-iodine - external RT may help

Describe lymphoma thyroid cancer

Rare May arise in pre-existing Hashimoto's thyroiditis External RT more helpful and combined with chemo

Describe medullary thyroid cancer

Arises from parafollicular C cells Often associated with MEN2 Serum calcitonin levels raised Treatment - total thyroidectomy Prognosis is variable