Clinical Thyroid Disease Flashcards
4 categories of thyroid disease
Hyperthyroidism
Hypothyroidism
Goitre
Thyroid cancer
3 parts of the thyroid gland
Right lobe
Left lobe
Isthmus
Hormone levels in primary hypothyroidism
Raised TSH (due to the body thinking you are hypothyroid) Low FT4 and FT3
Hormone levels in subclinical (compensated) hypothyroidism
Raised TSH
Normal FT4 and FT3
What is subclinical hypothyroidism?
The pituitary has been into overdrive and so the normal values have been maintained
Hormone levels in secondary hypothyroidism (pituitary)
Low TSH
Low FT4 and FT3
Investigations of hypothyroidism
TFTs - TSH/FT4 Autoantibodies; TPO (thyroid peroxidase antibodies) FBC (MCV increased) Lipids (hypercholesteraemia) Hyponatraemia Increased muscle enzymes, ALT, CK Hyperprolactinaemia
Presentation of hypothyroidism
Weight gain Lethargy Feeling Cold Constipation Heavy periods Dry skin/hair Bradycardia Slow reflexes Goitre Puffy face Large tongue Hoarse voice Coma
Presentation of hyperthyroidism
Weight loss Anxiety/irritability Heat intolerance Bowel frequency Light periods Sweaty palms Palpitations Hyperreflexia/tremors Goitre Thyroid eye symptoms/signs
Normal range of TSH
0.3-3.3
Normal range of FT4
10-25
What TFTs to look at first….
FT4 will tell you if patient has subclinical or overt disease
Then look at TSH
What happens in respect to autoimmunity in hypothyroidism?
The antibodies destroy the gland
What happens in respect to autoimmunity in hyperthyroidism?
The antibodies stimulate the gland
Causes of primary hypothyroidism
Congenital - developmental - dyshormogenesis Autoimmune thyroid disease - Hashimotos Post-op/post-radioactive iodine External RT for head and neck cancers Drugs - Antithyroid drugs - Amoidarones - Lithium - Interferon - Immune checkpoint inhibitors Chronic Iodine deficiency Post-subacute thyroiditis
What is the commonest reason for hypothyroidism in the UK?
Hashimotos
What is the commonest reason for hypothyroidism worldwide?
Chronic iodine deficiency
Causes of secondary/tertiary hypothyroidism
Pituitary tumour Craniopharyngioma Post pituitary surgery or radiotherapy Sheehans syndrome Isolated TRH deficiency
Your chance of thyroid progression is higher if you have a raised what?
TSH
What is the causes of primary thyrotoxicosis?
Graves disease (70%)
Toxic multinodular goitre (20%)
Toxic adenoma
What is thyrotoxicosis?
A condition due to excess thyroid hormones - therefore including hyperthyroidism
What is the cause of secondary thyrotoxicosis and how common is this?
Pituitary adenoma secreting TSH
quite rare
Causes of thyrotoxicosis without hyperthyroidism
Destructive thyroiditis
Excessive thyroxine administration
What can cause destructive thyroiditis?
Post partum
Subacute (De Quervains)
Amoidarone induced
What % of hyperthyroidism does graves disease make up?
70-80%
Which gender gets graves disease more?
F > M
Pathology of graves disease
Stimulating antibodies (thyroid peroxidase antibodies and TSH receptor antibodies)
What is the most common cause of thyrotoxicosis in the elderly?
Multinodular goitre
Will multinodular goitre go into spontaneous remission?
No
What is subacute (de Quervians) thyroiditis?
Thyroiditis due to a viral trigger e.g. enteroviruses, cockasackie
What age of patients get subacute/de quervians thyroiditis?
Generally younger patients < 50
Presentation of subacute/de quervians thyroiditis
Painful goitre Fever Myalgia ESR increased Thyrotoxicosis for a while(3-6 weeks) and then hypothyroid (3-6 months)
What may subacute/de quervians thyroidits require in the short term?
NSAIDs and steriods
Treatment of hyperthyroidism
RAI (radioiodine)
ATD (antithyroid drugs)
Surgery
Beta blockers
What is implicated in the management of symptoms in hyperthyroidism?
Beta blockers
What are the anti thyroid drugs?
Carbimazole
Propulthiourcacil
Two ways to give ATD
- Titration regime - start at highest dose then reduce dose when symptoms get better over time
- Block replace - start at high dose and then when symptoms improve, instead of cutting down, you add thyroxine
What does RAI do?
High dose which is ablative, destroying the gland
Cautions to take when have had radioiodine
Cant have contact with young children under 18 for 4 weeks
No contact with pregnant women
Can set off airport alarms
S/Es of RAI
70% hypothyroid
Eye problems
Concerns in subclinical hyperthyroidism
Decreased bone density in post menopausal women
AF 3x increase in over 60s
Treatment of hypothyroidism
Levothyroxine (T4) tablets
Doses of levothyroxine (T4) used in the treatment of hypothyroidism
Initial dose 50mcg/day
After 2 weeks increase to 100mcg
How to take levothyroxine?
Same time every day
Empty stomach
Not interfering with other medications
How long do the levels take to go back to normal after taking replacement of thyroxine?
6-8 weeks
What situations would you need to adjust the dose of levothyroxine and to what and why?
Ischaemic heart disease - start at lower dose and increase slowly as risk of precipitating angina
Pregnancy - need increased LT4 dose as increased thyroxine requirement
Postpartum thyroiditis - trial withdrawal
Myxedema coma - very rare emergency a coma from hypothyroidism - need IV T3 (steroid)
What would be present for you to consider for treatment in Subclinical hypothyroidism?
TSH > 10
TSH >5 if positive thyroid antibodies
TSH elevated with symptoms
Complications of treatment of subclinical hypothyroidism
Osteopenia and AF
How long do you trial for treatment for subclinical hypothyroidism and is this continued?
3 to 4 months
Continue if symptomatic improvement
What is there a risk of when treating subclinical hypothyroidism?
Overtreatment
When in the pregnancy do you need to increase levothyroxine dose?
Pre-conceptually
Types of thyroid cancer
Papillary Follicular Anaplastic Lymphoma Medullary
Most common type of thyroid cancer
Papillary
Features of papillary thyroid cancer
Multifocal, spread to lymph nodes
Good prognosis
Features of follicular thyroid cancer
Usually single lesion
Spreads by bloodstream
Metastases to lung and bone
Good prognosis if resectable
Treatment of thyroid cancer
Near total thyroidectomy and lymph node dissection
High dose radioiodine (ablative)
Prognosis of thyroid cancer is poor if….
< 16 y/o > 45 y/o Tumour size Spread outside tumour capsule TNM staging
What would need to be given after treatment with radioiodine?
Long term suppressive doses of thyroxine
What is the follow up after treatment for thyroid cancer?
Thyroglobulin checked once a year once stable
Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal)
Where does the tumour arise from in medullary thyroid cancer?
Parafollicular C cells
What is medullary thyroid cancer often associated with?
MEN 2
What is raised in medullary thyroid cancer?
Serum calcitonin levels
Treatment of medullary thyroid cancer
Total thyroidectomy
Why is there not a role for radioiodine in medullary thyroid cancer?
Because it is not a cancer of the thyroid cells
Causes of goitre
Puberty Pregnancy Grave's disease Hashimoto's Acute inflammation (De Quervians) Chronic fibrotic inflammation (Reidels) Iodine deficiency (endemic goitre) Dyshormogenesis Goitrogens
Types of goitre
Multinodular Diffuse Cysts Tumours Miscellaneous
In a solitary thyroid nodule, the risk of malignancy is higher in who?
Children Adults < 30 y/o or > 60 y/o Previous head and neck irradiation Pain Cervical lymphadenopathy
Investigations of a solitary thyroid nodule
TFTs Isotope scanning if low TSH (hot nodule) USS (benign vs malignant) FNA CXT/TXR if large retrosternal extensions
Hot nodule vs cold nodule
Hot - producing too much T3/T4
Cold - implies that area is not taking up enough
Drug used to treat hyperthyroidism
Carbamezole
Main side effect of carbamezole
Agranulocytosis
What is agranulocytosis?
Knocks out neutrophils
When treated with RAI, what will happen to the majority of people as a side effect?
Thyroid will go underactive (hypothyroid)
What test is used to look at the thyroid?
USS
What is often the pathology in primary hyperparathyroidism?
Only 1 gland over working
Indications for surgery of primary hyperparathyroidism
Very high Ca
Kidney stones
Thin bones
Penetrance of MEN 1 + 2
Very variable
What do MEN 1 + 2 involve?
Tumours involving 2 or more endocrine glands
Test for pheochromocytoma
Urinary catecholamines
What type of tissue are C cells?
Neuroendocrine
What cancer is a cancer of the C cells?
Medullary thyroid cancer
Pathology of C cells cancer
Calcification
Leading to medullary carcinoma
What is the problem with medullary thyroid cancer?
Tends to metastasise
What is the C cell cancer precursor?
C cell hyperplasia
Inheritance for MEN 1 + 2
Autosomal dominant
What does the MIBG scan pick up?
Neuroendocrine tissue
How common is MEN?
Really rare
Treatment of MEN 2A
Alpha blockage to reduce effect of adrenaline e.g. phenoxytozamine
What prophylactic treatment can be considered in MEN 2A?
Thyroidectomy
What nerve runs through the thyroid?
Recurrent laryngeal nerve
Autoantibodies (of the thyroid) are raised in what condition?
Both primary hypo and hyperthyroidism
What thyroid test is not measured routinely?
T3
Why must thyroxine treatment be started at a lower dose in older people?
Heart problems
What can interfere with thyroxine?
Iron supplements
Average dose of levothyroxine
125mg
Too much levothyroxine can lead to……
Heart problems
Osteopenia / porosis
Treatment of subclinical hypothyroidism
4.78 - 10 should be assessed but not automatically treated
What predicts the risk of overt hypothyroidism?
Anti-TPO
Eye signs of graves disease
Diplopia Dry eyes Exopthalmos Eye movement problems Lid lag Lid retraction Proptosis Periorbital oedema
What presentation of goitre is found in graves disease?
Smooth homogenous bilateral swelling
Pathology of post partum thyroiditis
Destructive mediated thyroiditis - inflammation
When does post partum thyroiditis occur?
8 weeks - 1 year post partum
Can post partum thyroiditis come back in further pregnancies?
Yes
What % of people with graves have TAB +ve?
70 - 80%
Does thyroiditis always give clinical signs? Why?
No
Not overactive - it is not manufacturing more hormones, it is just putting more into the blood
Treatment of thyroiditis
Manage symptoms e.g. beta blocker for tachycardia
How would you tell the difference between graves and thyroiditis?
Iodine uptake scan
- Graves would have an increased uptake as it is manufacturing new hormones
- Thyroiditis would have not a big as an increased uptake as it is not manufacturing new hormones
What is used for iodine in an iodine uptake scan?
Pertechestate
Does Toxic multinodular goitre tend to go into spontaneous remission?
No
How long is carbimazole taken for?
12 - 15 days
What is the optimal therapy for MN goitre?
RAI
When would RAI be used in graves?
Typically after relapse
What is there a risk of when using ATDs? How common is this?
Agranulocytosis
1:250
Thyroidectomies are only done when?
Intolerant of drug therapy
RAI not possible
TSH receptor antibodies are present in 90-100% of what?
Graves disease
Common clinical finding of graves disease
Pretibial myxoedema
Thyroid acropachy
Who are anti-TPO antibodies found in?
Hashimotos
What is thyroid acropachy?
Thickening of extremities
- Digital clubbing
- soft tissue swelling of hands and feet
- periosteal new bone formation
Effect of thyrotoxicosis on calcium levels
Hypercalcaemia
What is the most important modifiable risk factor for the development of thyroid eye disease?
Smoking
What is a thyroid storm?
Life threatening rare complication of thyrotoxicosis
Who is a thyroid storm seen in?
Patients with established thyrotoxicosis
What does NOT usually cause a thyroid storm?
Iatrogenic thyroxine
Precipitating events of thyroid storm
Thyroid / non thyroid surgery
Trauma
Infection
Acute iodine load e.g. CT contrast media
Presentation of thyroid storm
Fever > 38.5C Tachycardia Confusion and agitation Nausea and Vomiting HF HTN Abnormal LFTs (may have jaundice)
Treatment of thyroid storm
Symptomatic - paracetamol Treat underlying precipitating event BBs; typically IV propranolol ATDs; e.g. propylithiouracil Lugols iodine Dexamethasone
What does a tender goitre indicate?
DeQuervians/Subacute thyroiditis
What is used to monitor the recurrence of medullary thyroid cancer?
Serum calcitonin levels
