Tyhroid Disease Flashcards
Where is the thyroid oacted
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What is the pre tracheal fascia
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
How is the thyroid scanned frequently
Ultrasound scanning
Describe a normal thyroid scan
See slide
Decisive the through gland development
Down thyrogossal duct, around hyoid bone, down past larynx
What is a thyroglossal duct cyst
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
What is metabolic thyroid disease
• 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)
What does tsh level indicate
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)
Describe TSh and free T4 levels in thyroid disease
• 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…)
What are autoimmune diseases that comply affect endocrine glands
• 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
What are the prevalence of goitre in the UK
• 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
What ae the commonest causes of goitre globally
- 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) - 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
When is ion defivieny a particular concern
• 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
What is a multinodular goitre
Retrosternal mutinodular goitre
• A multinodular goitre may enlarge inferiorly into the superior
mediastinum to form a retrosternal goitre. This may cause tracheal
compression.
What are the symptoms of hypothyroidism
• 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
What are the signs of hypothyroidism
• 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)
What is myxoedema
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!
What are causes of hypothyroidism
• 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
What is the treatment for hypothyroidism
Treatment of hypothyroidism
• Oral thryoxine. Luckily not destroyed by gastric acid! • Adjust dose to normalise serum TSH
What are the symptoms of thyrotoxicosis
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
What are the signs of thyrotoxicosisi
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
What is elevator palpebrae Superior is music s
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
What are the causes of thyrotoxicosis due to hyperthyroidism
Causes of thryotoxicosis due to hyperthyroidism
1. Hyperthyroidism due to Graves disease 2. Toxic multinodular goitre 3. Toxic adenoma
What is Graves’ disease
• 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
