Tyhroid Disease

Question 1

Where is the thyroid oacted

Answer 1

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Question 2

What is the pre tracheal fascia

Answer 2

Attaches to the thyroid land to the trachea and larynx this the thyroid moves upwards on swallow get, an important diagnostic feature for lumps in the neck

Question 3

How is the thyroid scanned frequently

Answer 3

Ultrasound scanning

Question 4

Describe a normal thyroid scan

Answer 4

See slide

Question 5

Decisive the through gland development

Answer 5

Down thyrogossal duct, around hyoid bone, down past larynx

Question 6

What is a thyroglossal duct cyst

Answer 6

Thyroglossal duct normally disappears but remnants of epithelium remain an form a thyroglossal duct cuts. The cyst is usually near or within the body of the hyoid and fora a swelling in the anterior part o the neck always on the midline
A thyroglossal cyst moves upwards on tongue protrusion

Question 7

What is metabolic thyroid disease

Answer 7

• It is very, very, very rare for a pituitary adenoma (a benign tumour of glandular epithelial tissue) to produce TSH and lead to thyrotoxicosis
• Pituitary failure only very, very rarely presents with isolated hypothyroidism
• This means that 98% of metabolic thyroid (hyper or hypothyroidism) disease is due to a primary abnormality of the thyroid gland itself
So
• This means that the TSH level can be used as a screening test for
hyperthyroidism (TSH decreased) or hypothyroidism (TSH increased)

Question 8

What does tsh level indicate

Answer 8

In effect, the TSH level tells us what the patient’s own brain ‘thinks’ of the patient’s thyroid function. If the TSH is raised, then the thyroid gland is underfunctioning (hypothyroidism). If the TSH is low (supressed), then the thyroid gland is overfunctioning (hyperthyroidism)

Question 9

Describe TSh and free T4 levels in thyroid disease

Answer 9

• Hypothyroidism
– TSH increased
– Free T4 decreased
• Hyperthyroidism
– TSH decreased
– Free T4 increased
• Normal TSH range is 0.5 to 5.0 mIU/L and normal free T4 range is
10 to 25 pmol/L (do not learn, instead use local lab levels). Why
wide range? – because the hypothalamus and therefore TRH, TSH
and T4 are constantly responding to the environment (temperature,
light etc…)

Question 10

What are autoimmune diseases that comply affect endocrine glands

Answer 10

• Islets of Langerhans – Type 1 diabetes
• Thyroid
– Hypothyroidism (Hashimoto’s disease)
– Hyperthyroidism (Grave’s disease)
• Adrenal glands – Addison’s disease
• Autoimmune pituitary disease
• Autoimmune ovarian and testicular disease
In general, autoimmune endocrine diseases are more common in women. Why? – we don’t know

Question 11

What are the prevalence of goitre in the UK

Answer 11

• 7% of females
• 1% of males
Why more common in females? - Precise reason not known but there is increasing evidence that the oestrogen/progesterone ratio affects thyroid function

Question 12

What ae the commonest causes of goitre globally

Answer 12

1. Iodine deficiency. Reduced thyroxine levels lead to increased TSH
   which leads to generlised thyroid enlargement, usually nodular.
   Severe cases may become hypothryoid. 2.2 billion people are iodine deficient and 30% of the population live in iodine deficient
   areas (mainly mountainous areas)
2. Multinodular goitre (sometimes also called colloid goitre). Affects
   5% of Western populations and seven times commoner in women.
   Aetiology unknown. Normal thryoid function, although after many
   years a very small number may develop hyperthyoidism – toxic
   multinodular goitre
   By far the commonest cause of goitre in the UK

Question 13

When is ion defivieny a particular concern

Answer 13

• It is a particular concern during pregnancy • If a mother is iodine deficient and hypothyroid then the foetus is also
iodine deficient. This leads to a child with:
– Mental retardation – Abnormal gait – Deaf-mutism – Short stature – Goitre – Hypothyroidism

Question 14

What is a multinodular goitre

Answer 14

Retrosternal mutinodular goitre
• A multinodular goitre may enlarge inferiorly into the superior
mediastinum to form a retrosternal goitre. This may cause tracheal
compression.

Question 15

What are the symptoms of hypothyroidism

Answer 15

• Symptoms
– Excessive tiredness, feeling slowed down
– Memory problems, depression, psychosis (myxoedema medness)
– Weight gain
– Cold intolerance
– Gruff voice, croaky voice
– Puffy eyes , face hands and feet
– Dry, flaky skin
– Hair loss, particularly outer third of eyebrows
– Symptoms of carpal tunnel syndrome
– Constipation
– Menorrhagia (the odd one)
– Muscle weakness and cramps

Question 16

What are the signs of hypothyroidism

Answer 16

• May be no obvious signs! • Weight gain • Dry skin, coarse brittle hair, loss of outer third of eyebrows • Pallor. ‘Peaches and cream’ face • Coarse facial features and periorbital puffiness • Bradycardia • Hyporeflexia with delayed relaxation • Non pitting oedema – myxoedema. Due to deposition of
mucopolysaccharides, particularly around eyes, hands and feet • Ascites or pericardial effusion (both uncommon)

Question 17

What is myxoedema

Answer 17

As well as meaning non pitting oedema, particularly around the eyes,
hands and feet, the term myxoedema is also used to mean
hypothryoid in general. So if a doctor says “she has myxoedema”,
this means that she has hypothroidism – a bit confusing!

Question 18

What are causes of hypothyroidism

Answer 18

• Autoimmune destruction of the thyroid – Hashimoto’s disease. Ten
times commoner in women and 10% of women over the age of 30
years have Hashimoto’s thyroiditis. Antibodies to thyroglobulin and
thyroid peroxidase are present in the blood. Hashimoto’s disease
may be associated in the early stages with a small diffuse goitre (due
to inlammation) or the thyroid may never enlarge and shrink in size
from the beginning of the disease
• Severe iodine deficiency
• Post surgical removal of thyroid with inadequate thyroxine
replacement

Question 19

What is the treatment for hypothyroidism

Answer 19

Treatment of hypothyroidism

• Oral thryoxine. Luckily not destroyed by gastric acid! • Adjust dose to normalise serum TSH

Question 20

What are the symptoms of thyrotoxicosis

Answer 20

Symptoms of thyrotoxicosis (hyperthyroidism is thyrotoxicosis due to over production of thyroxine by the thyroid gland)
• Overactivity, tiredness
• Nervousness, anxiety, insomnia
• Shaking, trembling
• Heat intolerance
• Increased sweating – warm sweaty hands
• Palpitations. Rarely angina
• Weight loss in spite of increased appetite
• Diarrhoea
• Amenorrhea
• Proximal muscle weakness

Question 21

What are the signs of thyrotoxicosisi

Answer 21

Signs of thyrotoxicosis
• Weight loss • Warm sweaty hands • Fine hand tremor • Tachycardia. Atrial fibrillation • Bounding pulse – wide pulse pressure • Proximal myopathy • Lid lag - Lid lag Lid lag 2 • Staring eyes

Question 22

What is elevator palpebrae Superior is music s

Answer 22

Levator palpebrae superioris muscle. 90% skeletal muscle and 10 % smooth muscle. The smooth muscle portion is supplied by the sympathetic nervous system. Over stimulation of the sympathetic portion leads to ‘staring eyes’ and lid lag

Question 23

What are the causes of thyrotoxicosis due to hyperthyroidism

Answer 23

Causes of thryotoxicosis due to hyperthyroidism

1. Hyperthyroidism due to Graves disease 2. Toxic multinodular goitre 3. Toxic adenoma

Question 24

What is Graves’ disease

Answer 24

• Graves, a Dublin physician described a young woman with
exopthalmos, diffuse goitre, hyperthyroidism and pretibial
myxoedema. Graves’ disease is an autoimmune disease. The thyroid
component is caused by a circulating immunoglobulin called thyroid
stimulating immunoglobulin (TSI). This immunoglobulin attaches to
and stimulates the TSH receptor. The TSI causes all of the classical
signs and symptoms of thryotoxicosis, however the additional unique
features of Graves’ disease are:
– Exopthalmos (it is possible to have the exopthalmos alone) – Pre-tibial myxoedema (confusing because nothing to do with
hypothyroidism/myxoedema!)
• The exopthalmos and pre-tibial myxoedema are both part of the
autoimmune disease

Question 25

What is toxic multinodular goitre

Answer 25

• Not autoimmune. Therefore, no exopthalmos or pretibial myxoedema
• Develops in a very small proportion of patients with a multinodular
goitre

Question 26

What is toxic adenoma

Answer 26

Toxic adenoma
• A single adenoma develops in the thyroid and produces thyroxine
autonomously

Question 27

What is the treatment of thyrotoxicosis

Answer 27

Treatment of thryotoxicosis
• Carbimazole. This prevents thyroid peroxidase from coupling and
iodinating the tyrosine residues on thyroglobulin, thereby reducing
production of T4.
• Surgical excision of thyroid. Thyroidectomy
• Ablative dose of radioactive iodine

Question 28

What is thyroid cancer

Answer 28

Thyroid cancer
• Less than 1% of all thyroid nodules are malignant
• Thyroid cancer accounts for less than 1% of all cancers in the UK
• Thyroid cancers do not cause a metabolic disturbance (either hypo
or hyperthyroid)
• Presents as a thyroid nodule
• Prognosis is excellent – 97% cure rate!
Well differentiated - behave like normal thyroid tissu

Question 29

Summarise thyrid abnormalities

Answer 29

See slide