Clinical thyroid disease Flashcards
Symptoms of hypothyroidism
weight gain and lethargy cold intolerance constipation heavy periods dry skin/hair bradycardia slow reflexes goitre severe = puffy face, large tongue, hoarseness, coma
Symptoms of hyperthyroidism
weight loss heat intolerance bowel frequency light periods palpitations goitre thyroid eye symptoms hyperreflexia tremors
What is the “odd” symptom out when it comes to hyper/hypo thyroidism?
menstruation
List the TSH and FT3/4 for the 3 types of hypothyroidism
primary = TSH high, fT3/4 - low
secondary - both low
subclinical - TSH high, T3/4 - normal
Epidemiology of hypothyroidism
most common endocrine condition after Type 1DM
more women effected than men
subclinical hypothyroidism common in older women
1 in 3500 births - congenital hypothyroidism
Congenital causes of primary hypothyroidism
dyshormonogenesis
developmental eg agenesis
Acquired causes of primary hypothyroidism
autoimmune eg Hashimoto’s
Iatrogenic eg radioiodine, post operative
chronic iodine deficiency
post sub acute thyroiditis eg postpartum thyroiditis
Causes of secondary/tertiary hypothyroidism
pituitary tumour craniopharyngioma Isolated TRH deficiency post pituitary surgery Sheehan's syndrome
Investigations for hypothyroidism
TSH/fT4 autoantibodies - TPO FBC muscle enzymes lipids hyperprolactinaemia hyponatraemia
Most common treatment for hypothyroidism
levothyroxine - T4
Levothyroxine treatment regimen
50 micrograms a day –> 100 micrograms after 2 weeks
annual TSH testing
half life is 7 days
increase dose until TSH is normal
Other treatment methods for hypothyroidism
T3 tablets
mixture of T3/4 tablets
Treating hypothyroidism in someone with IHD
treatments increase heart rate
lower dose and increase cautiously
can precipitate angina
Treating hypothyroidism in pregnancy
Need more - higher levothyroxine dose
When should treatment be considered in subclinical hypothyroidism?
TSH>10
TSH>5 with positive thyroid antibodies
TSH elevated with symptoms - trial therapy
Risks of over treating (subclinical) hypothyroidism
AF
osteopenia
Why is it important to treat hypothyroidism (subclinical included) before/during pregnancy?
More levothyroxine is required
reduce risk of foetal loss and lower IQ
6 causes of goitre
physiological eg puberty/pregnancy autoimmune destruction eg graves/hashimotos iodine deficiency thyroiditis eg acute, chronic fibrotic dyshormonogenesis goitrogens
5 types of goitre
multinodular diffuse eg colloid, simple cysts tumours eg adenoma, carcinoma, lymphoma miscellaneous eg TB, sarcoidosis
Risk factors for solitary thyroid nodule malignancy
child, under 30, over 60
head and neck irradiation
pain, cervical lymphadenopathy
Investigations for solitary nodule thyroid
thyroid function test FNA isotope scanning if low TSH USS Chest and thoracic inlet x-rays
2 types of differentiated thyroid cancer
papillary
follicular
Papillary thyroid cancer
commonest, multifocal, local spread
excellent prognosis
Follicular thyroid cancer
mets - lung, bone
usually single lesion
good prognosis if treatable
Poor prognostic factors for thyroid cancer
spread out of capsule, under 16 and over 45, mets, TNM, tumour size
Management of thyroid cancer
thyroidectomy
high dose radioiodine
long term suppressive thyroxine
Follow up of thyroid cancer
thyroglobulin - tumour marker
whole body iodine scan followed by 2-4 weeks of thyroxine withdrawl
3 other types of thyroid cancer
anaplastic
lymphoma
medullary
Anaplastic thyroid cancer
rare, aggressive, locally invasive
poor prognosis - does not respond to radioiodine
Medullary thyroid cancer
parafollicular c cells
MEN 2 association
serum calcitonin increased
treat with total thyroidectomy and prognosis variable
3 broad causes of thyrotoxicosis
primary
secondary
thyrotoxicosis without hyperthyroidism
Primary causes of thyrotoxicosis
graves disease
toxic multinodular goitre
toxic adenoma
Secondary causes of thyrotoxicosis
pituitary adenoma secreting TSH
Causes of thyrotoxicosis without hyperthyroidism
excessive thyroxine administration
destructive thyroiditis
Investigation of Graves disease
family history - autoimmune
TSH receptor antibodies
Thyroid peroxidase antibodies
Diagnosis of graves disease
thyroid eye symptoms pretibial myxoedema clubbing gynaecomastia Hyperthyroidism Thyroid antibodies goitre
What is multinodular goitre?
common cause of thyrotoxicosis in elderly
no graves disease
will spontaneously go into remission
Explain subacute thyroiditis
younger patients with viral trigger eg enterovirus
painful goitre, myalgia, fever
ESR increased
followed by period of hypothyroidism - months
short term steroids and NSAIDs
Management of hyperthyroidism
radioactive iodine
anti-thyroid drugs
thyroidectomy
beta blockers - symptomatic
What is the main anti-thyroid drug?
carbimazole
Side effects of carbimazole
rash
agranulocytosis - neutropenia
2 methods of carbimazole administration
block-replace
titration regimen
Explain the titration regimen of carbimazole
start on high dose
reduce until 5mg/day is reached
most common method
50% cure, 30% hypothyroidism
Explain the block-replace method for carbimazole
block with carbimazole
replace with thyroxine
higher side effects
3 selected cases for long term low dose carbimazole
elderly
cardiac problems
unwilling for Radioactive iodine
When is radioactive iodine not used?
pregnancy and young people
with severe eye disease
2 methods of radioiodine administration
high dose ablative
variable calculated
Is high dose ablative or variable calculated used more for radio iodine administration?
high dose ablative
high chance of becoming hypothyroid
What is meant by subclinical hyperthyroidism? When should it be treated
TSH reduced but fT3/4 unaffected as of yet
AF and osteopenia risk
ATD/RAI if persistent and those at cardiac risk
