MEH - Thyroid Flashcards
Can you feel a normal sized thyroid on examination?
No
What is the pre-tracheal facia? Why is this relevant in diagnostics?
It attached the thyroid gland to the trachea and larynx, and so the thyroid moves up with swallowing. This is important when looking at lumps in the neck and where they originate from.
How else can you examine the thyroid other than palpation (2)?
Ultrasound is commonly used
Iodine scen - thyroid takes up iodine dye - can show enlarged lobes
Is the thyroid gland the first gland to develop in foetus?
Yes
When in foetal development does the thyroid develop and from what structure?
4-7weeks - from tongue - proliferation of epithelial cells.
What is a lingual thyroid?
An ectopic thyroid that has failed to migrate downwards during normal embryonic development - can see it when people open their mouths
What is the thyroglossal duct and what is a thyroglossal duct cyst? Where anatomically on the neck is this seen?
It is an embryological structure that allow the thyroid to migrate caudally during development, usually disappears, but remnants may remain and form a thyroglossal duct cyst. Seen within the body of the hyoid and is always at the front in the midline of the neck
Where does a thyroglossal cyst move to on tongue protrusion?
Moves upwards because of its attachment to the tongue
Define a cyst?
A fluid filled bag
What is metabolic thyroid disease used to describe? Does the abnormality most commonly come from the thyroid gland itself or the pituitary gland?
Over or underachieve thyroid
98% from thyroid gland itself
Rarely from pituitary gland - either benign adenoma releasing TSH, or pituitary failure causing hypothyroidism
What is thyrotoxicosis used to describe?
The main cause of thyrotoxicosis is hyperthyroidism
What would you measure to screen for hyper or hypothyroidism? Would it be high or low for both? Would free T4 levels be high or low for hypo and hyperthyroidism?
TSH levels
High = underactive
Low = overactive
Free T4
Low - underactive
High - overactive
Why are the ranges for normal TSH and T4 so wide?
Because there is a wide range of normal concentrations due to homeostasis responding to environment - temp/light/ etc.
Do autoimmune disease commonly affect endocrine glands? Give examples
Yes
E.g. pancreas Islets of Langerhans - T1 diabetes
Thyroid - Graves/Hashimotos
Adrenal - Addisons
Are autoimmune conditions more common in men or women?
Women
What does a goitre mean? What three types? Are they more common in men or women - do we know why?
A thyroid swelling can be single nodule, multi nodular, or diffuse.
More common in women 7% vs 1% male - maybe something to do with oestrogen/progesterone ratio
When might you get a physiological goitre (3)? Is thyroid function normal or not here?
Menarche - first menstrual cycle
Pregnancy
Menopause
Normal thyroid function
What is the most common cause of goitre globally compared to UK?
Globally - iodine deficiency
UK - multinodular - usually normal thyroid function
What happens with iodine deficiency causing a goitre?
Reduced thyroxin leads to overproduction of TSH - leads to thyroid enlargement - usually nodular. Can lead to hypothyroidism - really common esp in mountainous areas
What causes a multi nodular goitre?
Unknown cause - common un UK. More common in women. A small number go on to develop hyperthyroidism - toxic multinodular goitre.
What can happen to the foetus if iodine deficiency occurs in pregnancy?
If the mother is iodine deficient the foetus is too. Leads to mental retardation, short stature, abnormal gait, deaf-mutism, goitre, hypothyroidism.
How can a goitre cause tracheal compression and what might the symptom be?
If a multinodular goitre enlarges inferiorly into the superior mediastinum then it may compress the trachea - may cause inspiratory stridor due to the retrosternal goitre.
What general metabolic/menstrual/mental health symptoms arise from hypothyroidism (name a few). What is the typical facial colouring you may see?
Weight gain Lethargy Menorrhagia Cold intolerance Hairloss - particularly outer third of eyebrows Constipation If really bad - myxoedema Psychosis if severe
May see ‘peaches and cream’ pallor
What is myxoedema and how does it occur? What is it also used to describe?
Non-pitting oedema, especially in the face, hands, feet. Due to deposition of mucopolysaccharides (Glycosaminoglycans (GAGS)).
Also used to describe hypothyroidism in general
