7. Thyroid disease Flashcards
How do TSH and free T4/T3 levels relate to thyroid activity?
Hypothyroidism
- increseased TSH
- decreased free T4/T3
Hyperthyroidism
- decreased TSH
- increased free T4/T3
What is a goitre and what are the 3 types?
Swelling of the thyroid gland:
- diffuse
- multinodular
- single nodule
What is the prevalence of goitre in UK?
1% males
7% females - oestrogen/progesterone ratio affects thyroid function
At which stages in life can physiological goitre (normal thyroid function) occur at?
- menarche
- pregnancy
- menopause
What is the most common cause of goitre globally?
Iodine deficiency: reduced thyroxine levels… increased TSH… generalised thyroid enlargement (usually nodular).
Severe cases can become hypothyroid.
What is the most common cause of goitre in the UK?
Multinodular goitre
- affects 5% of Western pops.
- 7x more common in women
- aetiology unknown
What is the thyroid function in multinodular goitre?
normal, though very small no. may develop hyperthyroidism after many years (toxic multinodular goitre).
Why is iodine deficiency a particular concern during pregnancy?
If mother is iodine deficient and hypothyroid then the foetus is also iodine deficient. Leads to cretinism: - mental retardation - abnormal gait - deaf-mutism - short stature - goitre - hypothyroidism
Name a possible complication of multinodular goitres.
may enlarge inferiorly into superior mediastinum to form a retrosternal goitre - may cause tracheal compression and respiratory problems (inspiration stridor)
Name a 3rd possible cause for goitre (without metabolic dysfunction). How does this present and what is the prognosis?
thyroid cancer (<1% of all cancers in UK)
- don’t cause metabolic disturbance
- present as thyroid nodule
- prognosis is excellent - 97% cure rate
Name some hypothyroidism symptoms.
1- lethargy
2- weight gain
3- intolerance to cold
4- bradychardia
5- constipation
6- dry skin
7- hair loss (alopecia), esp. outer 1/3 of eyebrows
8- myoedema (puffy eyes, face, hands and feet) and associated carpal tunnel syndrome symptoms
9- hoarse voice
10- memory problems, depression, psychosis (myxoedema medness)
11- menorrhagia
Name some signs of hypothyroidism.
- weight gain
- dry skin, coarse brittle hair, loss of outer 1/3 of eyebrows
- pallor - ‘peaches and cream’ face
- coarse facial features and periorbital puffiness
- bradycardia
- hyporeflexia with delayed relaxation
- non-pitting oedema - myxoedema - around eyes, hands and feet
- ascites or pericardial effusion (both uncommon)
Why does myxoedema occur in hypothyroidism?
deposition of mucopolysaccharides
What is the main cause of hypothyroidism?
Hashimoto’s disease (autoimmune destruction of thyroid follicles) - antibodies to thyroglobulin and thyroid peroxidase are present in blood
10x more frequent in women
Is Hashimoto’s disease associated with goitre?
may be associated in early stages with a small diffuse goitre (due to inflammation)