Clinical Thyroid Disease Flashcards
What is the name given to the part of the thyroid gland which connects the right and left lobe?
Isthmus
Explain how thyroid function is controlled.
Hypothalamus produces TRH.
TRH acts on anterior pituitary.
Stimulates production of TSH.
Thyroid produces T3, the active component.
There is a negative feedback system so if there’s too much of anything, it can loop back and turn the production of the cycle off.
If the source of an endocrine condition is at the thyroid gland, what is this called?
Primary hypothyroidism
If the source of an endocrine condition is at the pituitary gland, what is this called?
Secondary hypothyroidism
List some of the symptoms of hypothyroidism.
Fatigue/lethargy
Cold intolerance
Weight gain
Non-specific weakness
Constipation
Depression
Dry skin
Thyroid pain
List some of the signs of hypothyroidism.
Coarse, dry hair
Skin and hair loss
Oedema
Vocal changes
Goitre
Bradycardia and diastolic hypertension
Delayed reflexes
Paraesthesia
What tests would you do if you suspected hypothyroidism?
Check TFT (thyroid function tests)
Possibly FBC and glucose too
What does TFT’s check for?
TSH
Free T4
In those with hyperthyroid disease, what are T3/4 levels like?
Increased
In those with hyperthyroid disease, what are TSH levels like?
Decreased
->too much TH so not releasing anymore
In those with hypothyroid disease, what are T3/4 levels like?
Decreased
In those with hypothyroid disease, what are TSH levels like?
Increased
->to try and release more TH
Which medication can be used to help in the treatment of hypothyroidism?
Levothyroxine
In adults <65 with hypothyroidism, how much levothyroxine should be given?
1.6 mcg per kg
In adults >65 or with pre-existing cardiac disease and hypothyroidism, how much levothyroxine should be given?
More cautious levels- 25-50mcg
->more cautious as medication can rapidly increase HR
At what point in the day should levothyroxine be taken?
First thing in the morning on an empty stomach
->if unable, late evening, at least two hours after meal
List the signs/symptoms of hypothyroidism.
Weight gain
Lethargy
Feeling cold
Constipation
Heavy periods
Dry skin/hair
Bradycardia
Slow reflexes
Goitre
List the signs/symptoms of hyperthyroidism.
Weight loss
Anxiety/irritability
Heat intolerance
Bowel frequency
Light periods
Sweaty palms
Palpitations
Hyperreflexia
Goitre
Thyroid eye symptoms
What is the most common endocrine condition?
Diabetes
-> hypothyroidism is the second most common
What is the most common cause of primary hypothyroidism?
Congenital- either developmental or dyshormonogenesis (hormones not getting produced or released)
If hypothyroidism isn’t diagnosed and treated quickly, it can lead to physical and mental retardation. How is this prevented?
Every baby screened in UK
What are some of the causes of acquired hypothyroidism?
Autoimmune thyroid disease
Iatrogenic cause
Chronic iodine deficiency
Post-subacute thyroiditis
Give an example of an autoimmune thyroid disease which can cause acquired hypothyroidism?
Hashimotos
List some causes of secondary/tertiary hypothyroidism.
Pituitary tumour
Post pituitary surgery/ radiotherapy
Suppressed TSH has an increased risk of what?
Atrial fibrillation
Osteopenia
Fracture
What is subclinical hypothyroidism?
Elevated TSH to ensure that FT3/4 levels are normal
->therefore, the pituitary gland is working a lot harder
What are some of the causes of primary hyperthyroidism?
Grave’s disease
Toxic Multinodular Goitre
Toxic adenoma
What is another term for hyperthyroidism?
Thyrotoxicosis
What is usually the cause of secondary hyperthyroidism?
Pituitary adenoma secreting TSH
What is meant by thyrotoxicosis without hyperthyroidism?
Thyroid gland itself is not producing excess TH, it is due to destructive thyroiditis
What causes the majority of cases of hyperthyroidism?
70-80%
What is Grave’s disease?
An autoimmune driven condition in which stimulating antibodies stimulate the thyroid gland to overproduce TH
Which antibodies in Grave’s disease stimulate the thyroid gland to overproduce TH?
TSH receptor antibodies
How is a diagnosis of Grave’s disease made?
When patient has hyperthyroidism and is thyroid receptor antibody positive
What is the most common cause of thyrotoxicosis in the elderly?
Multi-nodular goitre
Who is more likely to be affected by subacute thryoiditis?
Younger patients <50yrs
What often triggers subacute thyroiditis?
Viral trigger
What are the symptoms of subacute thyroiditis?
Painful goitre
Fever/myalgia
ESR increased
Which medications are given to those with subacute thyroititis?
Short terms steroids and NSAIDs
What are the three treatment options for hyperthyroidism?
Antithyroid drugs
Radioiodine
Surgery
->antithyroid drugs do not cure the condition but are a holding measure
Which type of drug can be used to reduce some of the manifestations of hyperthyroidism e.g. tremors, tachycardia, palpitations?
Beta blockers
Give two examples of antithyroid drugs.
Carbimazole
Propylthiouracil
What are some of the side effects of antithyroid drugs?
Rash
Agranulocytosis*- serious
-> * deficiency of granulocytes in the blood, causing increased vulnerability to infection.
What should be done if a patient on antithyroid drugs has a severe sore throat or mouth ulcers or infections out of the ordinary?
FBC
In selected cases of hyperthyroidism, long term low does antithyroid drugs may be used. Give some examples of patients who may be treated using this option
Elderly
Those with cardiac complications
Patients who are unwilling for radioiodine or surgery
What can radioiodine cause as a result?
Hypothyroidism
What are some of the negatives of radioiodine?
Stays in thyroid glad for four weeks but anyone the patient comes into contact with is exposed to radiation from the radioiodine.
Can trigger eye disease
->worth warning that the radiation can set off security alarms in airports for a couple of months
What line of treatment if radioiodine usually?
Usually second line of treatment
A 38yo women with two children has a reoccurrence of Graves hyperthyroidism. What would be the probable choice of treatment?
Surgery
->not radioiodine as would expose her children to radiation
What is subclinical hyperthyroidism?
TSH supressed but normal free TH
What are some of the concerns of subclinical hyperthyroidism?
Decreases bone density
Can increase risks of AF
What are the treatment options for subclinical hyperthyroidism?
If persistent, antithyroid drugs or radioiodine to treat, especially those who are elderly or those w increased cardiac risk
There is a genetic condition called RTH (resistance to TH). What are FT3/4 levels and TSH levels like in this condition?
TSH normal or slightly elevated
FT3/4 elevated
Goitre?
Swelling of the thyroid gland
What are some of the physiological causes of goitre?
Puberty
Pregnancy
What are some of the autoimmune causes of goitre?
Graves disease
Hashimoto’s disease
What are some of the thyroiditis related causes of goitre?
Acute/ de Quervain’s
Chronic fibrotic/Reidel’s
What are some of the other causes of goitre?
Iodine deficiency
Dyshormogenesis
Goitrogens- medications blocking the formation of thyroid hormones
List some of the different types of goitre.
Multinodular
Diffuse
Cysts
Tumours
Miscellaneous
What is a single nodule in the thyroid known as?
Solitary nodule
Who is at increased risk of malignancy via a solitary nodule of the thyroid?
Children
Adults <30 or >60
Previous head and neck irridation
What % chance is there that the solidary nodules of the thyroid turn malignant?
5%
Which investigations are used for investigating solitary nodule of the thyroid?
TFT’s
Ultrasound- to differentiate between benign and malignant
Fine needle aspiration
What is the usual first line investigation of solitary thyroid nodules?
Ultrasound
-> then if ultrasound is suspicious, FNA carried out
Thyroid cancer can be termed as differentiated or undifferentiated.
Name the two classicisation’s of differentiated thyroid cancer.
Papillary
Follicular
Which type of differentiated thyroid cancer is more common?
Papillary
Describe papillary thyroid cancer.
Commonest
Multifocal, local spread to lymph nodes
Describe follicular thyroid cancer.
Usually a single nodule
Metastases to lung/bone
Differentiated thyroid cancer usually has a good prognosis.
What are some of the factors in which prognosis is likely to be poorer?
Age <16 or >55
Bigger tumour size
Spread outwith thyroid capsule
What is the treatment for thyroid cancer?
Near total thyroidectomy
-> if high risk, high dose radioiodine would be considered
Those who have had thyroid cancer will have to be on long term doses of what?
Long term suppressive doses of thyroxine
What is the marker for thyroid cancer?
Thyroglobulin
What treatment is used if it is thought that the thyroid cancer has a high chance of spreading?
Radioiodine ablation
Describe anaplastic thyroid cancer
Aggressive and locally invasive
Very poor prognosis
Does not respond to radioiodine
Describe thyroid lymphoma.
Rare, may arise from pre-existing Hashimotos.
External RT more helpful, combined with chemo
In medullary thyroid cancer, where does the tumour arise from?
Parafollicular C cells
What is medullary thyroid cancer often associated with?
MEN 2
What is the treatment for medullary thyroid cancer?
Total thyroidectomy
-> no role for radioiodine
