Thyroid disorders Flashcards
Hypothyroidism types of causes
- autoimmune thyroiditis
- iatrogenic
- drug induced
- iodine deficiency
- congenital
Autoimmune thyroiditis
Cell + antibody-mediated destruction of thyroid tissue
Can be either:
- Hashimoto’s thyroiditis
- Thyroid atrophy
Iatrogenic causes of hypothyroidism
thyroidectomy
radioactive iodine treatment
Name some drugs that can cause hypothyroidism
lithium
interferon alpha
amiodarone (an antiarrythmic)
What is myxoedema
accumulation of mucopolysaccharide in subcut tissues (hypothyroidism)
Symptoms of hypothyroidism
myxoedema tiredness weight gain dry, rough skin cold intolerance mental slowness
Ix hypothyroidism
raised serum TSH
serum free T4 & T3 would be low
hyponatraemia (from raised ADH levels)
anaemia
hyperlipidaemia
Mx hypothyroidism
synthetic levothyroxine (T4)
Aim: normalise serum TSH concentrations. Titrate according to TSH
Thyroid function test after at least 6 weeks on a steady dose
euthyroid
having a normally functioning thyroid gland
what is Hashimoto’s thyroiditis
atrophic changes with regeneration –> goitre formation
TPO antibodies are present, often very high
Tx Hashimoto’s thyroiditis
Levothyoxine may shrink goitre even when patient it not hypothyroid
Which thyroid autoantibodies are present in almost all patients with autoimmune hypothyroidism?
thyroglobulin
thyroid peroxidase (TPO)
what is the leading cause of hyperthyroidism?
Graves’ disease
What happens in Graves’ disease?
IgG antibodies bind to TSH receptor stimulating thyroid hormone production
Presentation of hyperthyroidism
Weight loss Increased appetite Irritability Tremor Heat intolerance Tachycardia AF
Clinical features specific to Graves’
opthalmopathy
pretibial myxoedema (raised red lesions on front of shins)
thyroid acropachy - clubbing, swollen fingers
Ix hyperthyroidism
Serum TSH is suppressed
Serum free T4 + T3 are elevated
What antibodies are present in most Graves’?
thyroid stimulating immunoglobulin (TSI)
thyroid peroxidase + thyroglobulin antibodies
Drug treatment for hyperthyroidism?
Thionamines e.g. carbimazole
Decrease synthesis of new thyroid hormone
- block + replace for Graves’
- short course to render euthyroid before other Tx
- long term if unwilling of other Tx
What drugs for rapid symptomatic control in hyperthyroidism?
Beta-blockers
As many symptoms are from sympathetic nervous system
Further treatments for hyperthyroidism (not drugs)
Radioactive iodine ablation
Surgery - only if patients rendered eurothyroid
what symptoms are specific to ophthalmic graves disease?
protruding eyeballs
limitation of eye movement
(lid lag + retraction could be any hyperthyroid)
pathphy of ophthalmic graves’ disease
?TSH receptor antibodies bind to TSH receptors in retro-orbital connective tissue
R-O inflammation of muscles + CT behind eyes
leads to opthalmopathy, peiorbial oedema, more severe in smokers
Mx ophthalmic Graves’ disease
stop smoking
correct thyroid dysfunction
artificial tears
predisposition to thyroid autoimmunity (Graves’ disease)
RF: F and postpartum
HLA-DR3
Envinromental: stress, high iodine intake, smoking
How to distinguish between benign and malignant thyroid nodules?
fine needle aspiration cytology
treatment of follicular and papillary cancers?
thyroidectomy with neck dissection for local nodal spread
then ablative radioactive iodine
treatment for anaplastic carcinoma and lymphoma?
maybe external radiotherapy
otherwise Tx is largely palliative
how do most thyroid cancers present?
asymptomatic thyroid nodules
1st sign of disease in thyroid cancer?
lymph-node mets
rarely bone and lung mets
what features suggest carcinoma in a patient presenting with a thyroid nodule?
Hx of progressive increase in size
hard and irregular nodule
enlarged lymph nodes on examination
what is myxoedema coma
loss of brain function from severe, longstanding low level of thyroid hormone in the blood (hypothyroidism)
