Clinical thyroid disease - First half Flashcards by Michael Alcorn

What are the main thyroid disorders?

Hypothyroidism

Hyperthyroidism

Goitre

Thyroid cancer

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Identify the labels on the diagram below

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What are the symptoms of hypothyroidism?

Hypothyroidism:

Weight gain
Lethargy
Feeling cold
Constipation
Dry skin/hair, hair loss
Heavy periods

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What are the signs of hypothyroidism?

Dry skin/hair

Goitre

Bradycardia

Slow reflexes

Puffy face

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How does severe hypothyroidism present?

Normal symptoms and…

puffy face

large tongue

hoarseness

coma

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What are the symptoms of Hyperthyroidism?

Hyperthyroidism:

Weight loss
Anxiety/irritability
Heat intolerance
Light periods
Thyroid eye symptoms

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What are the signs of hyperthyroidism?

Sweaty palms

Palipitations

Hyperreflexia/Tremors

Goitre

Thyroid eye symptoms/signs

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What are the clinical types of hypothyroidism and their differences?

Primary (Thyroid):

Raised TSH, Low FT4 & FT3

Subclinical (compensated):

Raised TSH: Normal FT4 & FT3

Secondary (Pituitary):

Low TSH, Low FT4 & FT3

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How common is hypothyroidism?

Commonest endocrine condition after diabetes

1/50 women get it

1/1000 men get it (very rare in men)

Subclinical hypothyroidism quite common in women over 60 (10%)

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What are the congenital causes of hypothyroidism?

Developmental:

Agenesis / maldevelopment

Dysmorphogenesis:

genetic defects for synthesis of thyroid hormone

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How common are congenital causes of hypothyroidism?

1 in 3500 births

All babies screened in the UK

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What are the acquired types of primary hypothyroidism?

Autoimmune:

Atrophic - most common
Hashimoto’s thyroiditis

Iatrogenic:

Postoperative / post- radioactive iodine
Radiotherapy for head/neck cancers
Antithyroid drugs, Amiodarone, Lithium, Interferon

Chronic iodine deficiency

Post-partum

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What are the causes of secondary hypothyroidism?

Pituitary or hypothalamic damage:

Pituitary tumour
Craniopharyngioma - _{Benign brain tumour begings near the pituitary}
Post pituitary surgery or post radiotherapy

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How do you investigate hypothyroidism?

Serum TSH _{- High TSH confirms primary hypothyroidism}

Serum FT₄ _{- Free thyroxine.}

Abnormalities of levels of TSH & FT₄ - used to determine which type of hypothyroidism

Autoantibodies - TPO (thyroid peroxidase antibodies)

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How is hypothyroidism treated?

Levothyroxine _{- for life, very little side effects. 50 - 150 ug.}

Other:

Liothyronine (T₃ replacement)

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Describe the doses n shit for levothyroxine

Initial dose Levothyroxine 1.6 ug/kg for adults <65 years old

In practice:

100 ug for young and fit
50 ug for old and small

Dosage then increased until suffice

How is hypothyroidism treated in those with ischaemic heart disease?

Start at lower dose 25 ug and increase cautiously; risk of precipitating angina

How is postpartum thyroiditis treated?

Trial withdrawal and measure TFT’s in 6 weeks

(normally self-limiting)

If a patient has is in a myxedemic coma

How are they treated for their hypothyroidism?

Very rare emergency, may need IV T3 (steroid)

A patients thyroid hormone tests have come back showing raised TSH but normal levels of FT₃and FT₄

Describe their investigation and management

Repeat thyroid hormone tests after 2-3 months and also test TPO antibodies

If TSH > 10 - treatment

If TSH > 5 and they are symptomatic - trial therapy

If pregnant/planning to be pregnant - treat

What is the risk of overtreatment with subclinical hypothyroidism?

Osteopenia (pre-osteoporosis)

Atrial fibrillation

Basically just too much thyroid is bad innit

Describe the management plan for someone with hypothyroidism during pregnancy?

Increased levothyroxine requirements during pregnancy

Specific management:

Increase Levothyroxine dosage by 25%
- Monitor closely
Aim to keep TSH in low normal range (<2.5mU/l) and FT4 in high normal range

Treat subclinical hypothyroidism if planning/pregnant

Why is important to manage hypothyroidism tightly in pregnancy?

Inadequately treated hypothyroidism linked with increased foetal loss and Lower IQ

What is Goitre?

Swelling of the neck resulting from some form of enlargement of the thyroid gland

What are the types of goitre shape?

**Nodular**: * Multinodular goitre * Solitary thyroid nodule (*solitary nodular goitre)* **Diffuse** **Tumour** **Miscellaneous**

What are the causes of diffuse goitre? (obviously different causes may produce slightly different looking diffuse goitre to this)

**Puberty & pregnancy** - this is called **simple goitre** **Autoimmune thyroid disease** **Acute thyroiditis** (de Quervain's thyroiditis) Iodine deficiency (endemic goitre) Dyshormonogenesis Goitrogens

What autoimmune conditions can cause diffuse goitre?

Graves' disease (thyrotoxicosis) Hashimoto's disease

Solitary thyroid nodules may be due to tumours What are risk factors for a patient with a solitary thyroid nodule having a tumour?

–Child –Adults less than 30 or over 60 years –Previous head and neck irradiation –Pain, cervical lymphadenopathy

What investigations should be done on a solitary thyroid nodule?

**Thyroid function tests** (T3,4, TSH) **Ultrasound** **FNA**

What are the main types of thyroid malignancy? For each type, what is their: a) frequency b) spreading behaviour c) prognosis

Papillary (carcinoma): * most common type (70%), esp. in young people * Multifocal, local spreading to lymph nodes * Good prognosis Follicular (carcinoma): * 20% of cases, more common in females * Metastasises to lung/bone * Good prognosis if resectable Other: * Medullary cell * Anaplastic * Lymphoma

How is thyroid cancer managed?

1) - Primary treatment option is **surgical**: * Total or near-total thyroidectomy 2) - High dose radio-iodine post-operative 3) - Levothyroxine - long term suppressive doses to stop recurrence Followups: * Monitor serum **thyroglobulin** as a tumour marker * Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal or recombinant TSH injections)

For **anaplastic** thyroid cancer, describe the following: a) behaviour and spreading b) prognosis

**Anaplastic:** a) - Aggressive and locally invasive b) - Very poor prognosis

For thyroid lymphoma, answer the following. a) Frequency and specific risk factors/causes b) Management

a) Rare - may arise from preexisting Hashimoto's disease b) Radiotherapy and chemotherapy

What is medullary cell thyroid cancer?

Carcinomas that arise from parafollicular (C-cells) cells They are quite rare, but is often associated with MEN 2 - phaeochromocytoma & hyperparathyroidism They cause serum calcitonin levels to be raised