Clinical Thyroid Disease Flashcards
What are some symptoms of hypothyroidism?
Fatigue/lethargy, cold tolerance, weight gain, non specific weakness, constipation, menstrual irregularities, depression, dry skin, and thyroid pain
What are some signs of hypothyroidism?
Coarse dry hair/skin, oedema (including eyelids), vocal changes, goitre, bradycardia, delayed reaction of deep tendon reflexes and paraesthesia
What do hypothyroid symptoms overlap with?
Euthyroid symptoms
What tests should be done for hypothyroidism?
Check TFTs - TSH and free T4
Consider also checking FBC and glucose/ HbA1c
What are the typical results of hypothyroidism?
FT3/4 decreased
TSH increased
What should a patient with hypothyroidism be started on?
Start Levothyroxine at 1.6 micrograms per Kg daily
If over 65 or cardiac disease then 25 to 50 micrograms a day
Measure TFTs every 3 months until TSH has stabilised
Also test thyroid peroxidase antibodies
How should Levothyroxine be taken?
Taken first thing in the morning and swallowed with water on an empty stomach
Also start on high dose
What are the key points of hypothyroidism?
Weight gain, lethargy, feeling cold, constipation, heavy periods, dry skin/hair, bradycardia, slow reflexes, goitre and severe puffy face
What are the key points of hyperthyroidism?
Weight loss, anxiety, heat intolerance, bowel frequency, light periods, sweaty palms, palpitations, hyperreflexia, tremors, goitre and thyroid eye symptoms
What is the prevalence of hypothyroidism?
Commonest endocrine condition after diabetes
Can also have subclinical hypothyroidism
What are some congenital causes for primary hypothyroidism?
Developmental - agenesis/ maldevelopment
Dyshormonogenesis - trapping/ organification of iodine
All babies screened at birth
What are some acquired causes of primary hypothyroidism?
Autoimmune thyroid disease - Hashimoto’s
Iatrogenic - post op, post radiotherapy, anti-thyroid drugs
Chronic iodine deficiency
Post subacute thyroiditis
What are some causes of secondary/ tertiary hypothyroidism?
Pituitary/ hypothalamic damage -
Pituitary damage, craniopharyngioma, and post pituitary surgery/ radiotherapy
What are the typical results of subclinical hypothyroidism?
Normal FT3/4
Increased TSH - working harder to control the normal range of T4
How should subclinical hypothyroidism be treated?
TFTs and thyroid peroxidase antibodies test
If more than 10mU/L treat like overt hypothyroidism
Or if symptoms trial medication
If not then monitoring
What are some alternative causes for hypothyroid symptoms?
DM, adrenal problems, hypopituitarism, coeliac, anaemia, hypercalcaemia, BB, statins, opioids, chronic liver or kidney disease, obesity, and stress
Describe thyroid pregnancy and how medication would change
Adequate preconception replacement
Empirical dose increase in early pregnancy
Regular monitoring
Aim is for TSH in lower half of normal range
Post natal - reduce levothyroxine to pre-pregnancy dose and re check
What percentage of treated hypothyroid patients have subclinical hyperthyroidism?
20%
What are the risks of overtreatment for hypothyroidism?
AF and osteopenia/ fracture
What are the typical test results of hyperthyroidism?
Increased FT3/4
Reduced TSH
What is the typical test results of subclinical hyperthyroidism?
Normal FT3/4
Reduced TSH
What are the primary causes of thyrotoxicosis (hyperthyroidism)?
Grave’s disease
Toxic multinodular goitre
Toxic adenoma
What are the secondary causes of thyrotoxicosis?
Pituitary adenoma secreting TSH
What are some causes of thyrotoxicosis without hyperthyroidism?
Destructive thyroiditis - post-partum and subacute Quervain’s
Excessive thyroxine administration
Describe Grave’s disease
70-80% of hyperthyroidism cases
More females
Autoimmune driven - thyroid peroxidase antibodies, TSH receptor antibodies which stimulate thyroid to produce more TH
How is Grave’s disease diagnosed?
Hyperthyroidism
Thyroid antibodies - TSH receptor antibodies
Symptoms and signs - thyroid eye disease, goitre, acropachy…
Describe multi-nodular goitre
Most common cause of thyrotoxicosis in elderly
Goitre and absence of Grave’s
Will not go into spontaneous remission
Describe subacute (de Quervain’s) thyroiditis
Generally younger patients <50
Viral trigger
Often recall painful goitre and possible fever/ myalgia and ESR elevated
May require short term steroids and NSAIDs
What is used for management of hyperthyroidism?
Radio-iodine therapy
Anti-thyroid drugs
Surgery
BBs for tremor, tachycardias and palpitations
What are the anti-thyroid drugs used?
Carbimazole
Propylthiouracil - more side effects
Can use titration regimen or block then replace (more side effects)
Both can cause hypothyroidism and 50% cure
What are the side effects to anti-thyroid drugs?
Both can cause agranulocytosis
Propylthiouracil - rash
Both hypothyroidism
When is long term dose of ATD used?
Elderly
Cardiac complications
Unwilling for RAI
Describe radio-iodine therapy
Definitive treatment
High dose ablation had most cure rate but more chance of hypothyroidism
Compared to variable calculated but less cure and hypothyroidism
May need steroids
When is RAI avoided?
In severe eye disease
Describe subclinical hyperthyroidism
TSH supressed but normal free TH
Concerns if bone density is decreased postmenopausal and AF
Treatment - ATD/ RAI if persistent esp. if older and risk of cardiac risk
What are the typical results of secondary hypothyroidism?
FT3/4 decreased
TSH normal or low
What is the results of resistance to thyroid hormone (TSHoma)?
Increased FT3/4
Normal or increased TSH
What are some causes for goitre?
Puberty, pregnancy, Grave’s, Hashimoto’s, acute thyroiditis, chronic fibrotic thyroiditis, iodine deficiency, dyshormogenesis and goitrogens
What are the different types of goitre?
Multinodular goitre, diffuse (colloid or simple), cysts, tumours and miscellaneous - sarcoidosis and TB
Describe a solitary nodule thyroid
Risk of malignancy - child, adults between 30-60, previous head/ neck irradiation and cervical lymphadenopathy
5% chance of malignancy
What are the investigations for solitary thyroid nodule?
Thyroid function tests
Then US
Then fine needle aspirations - Thy1 inadequate
Thy2 benign
Thy5 cancer
Describe thyroid cancer incidence
Most common endocrine malignancy
Lowe mortality than most cancers
What are the types of differentiated thyroid cancer?
Papillary and Follicular
Describe papillary thyroid cancer
Commonest
Multifocal and local spread to lymph nodes
Good prognosis
Describe follicular thyroid cancer
Usually single lesion
Metastases to lung/ bone
Good prognosis if resectable
When is prognosis poorer for thyroid cancer?
If age less than 16 or more than 55
Tumour bigger than 4cm
Spread outside thyroid capsule and metastasised
TMN staging
Explain thyroid cancer management
Near total thyroidectomy
High dose radio-iodine
Long term suppressible doses of thyroxine
Follow up - thyroglobulin marker
Whole body iodine scanning and dynamic risk stratification
What increases the likelihood of giving radio-iodine?
Bigger tumours, multifocal, invasion, adverse histology and large lymph nodes
Describe anaplasic thyroid cancer
Less than 5% of thyroid cancers
Aggressive and locally invade
Very poor prognosis as does not respond radio-iodine - external RT may help
Describe lymphoma thyroid cancer
Rare
May arise in pre-existing Hashimoto’s thyroiditis
External RT more helpful and combined with chemo
Describe medullary thyroid cancer
Arises from parafollicular C cells
Often associated with MEN2
Serum calcitonin levels raised
Treatment - total thyroidectomy
Prognosis is variable
