Thyroid Disease Flashcards by David Houghton

What term us used to describe normal thyroid function?

eu = normal
thyroid = thyroid
euthyroid

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What does the term thyrotoxicosis relate to?

toxic levels of thyroid hormones in the circulation

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What is the difference between thyrotoxicosis and hyperthyroidism?

thyrotoxicosis = increased levels of thyroid hormones in circulation
hyperthyroidism = increased secretion of thyroid hormones from thyroid gland

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What does the term goiter refer to in relation to the thyroid gland?

abnormal growth of the thyroid gland

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Hypothyroidism is a low production of thyroid hormones and can be separated into primary and secondary. What is primary and secondary hypothyroidism?

primary = issue with thyroid gland not secreting sufficient thyroid hormones
secondary = issue with hypothalamus and/or pituitary gland

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Which vertebrae does the thyroid gland align with?

C5 -T1

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Which cartilage does the thyroid gland wrap around in the neck region?

cricoid cartilage

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Label the image below using these labels:

thyroid cartilage
cricoid cartilage
right lobe of thyroid gland
isthmus
left lobe of thyroid gland
trachea

1 - cricoid cartilage
2- right lobe of thyroid gland
3 - trachea
4 - isthmus
5 - left lobe of thyroid gland
6 - thyroid cartilage

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In order for thyroid hormones triodothyronine (T3) and thyroxine (T4) to have an affect at tissue throughout the body there are 3 stages of the positive feedback loop. These are essentially the stages that result in T3 and T4 being secreted and reaching the target tissue. What are the 3 stages?

1 - hypothalamus signals the pituitary gland
2 - pituitary gland signals the thyroid gland
3 - triiodothyronine (T3) signalling in tissue and thyroxine (T4) signalling in the circulation

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There are 3 common thyroid tests that are conducted, namely thyroid stimulation hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4). What are the normal levels of TSH secretion?

0.3 - 3.5 mU/L

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There are 3 common thyroid tests that are conducted, namely thyroid stimulation hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4). What are the normal levels of FT4 secretion?

10 - 25 pmol/L

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There are 3 common thyroid tests that are conducted, namely thyroid stimulation hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4). What are the normal levels of FT3 secretion?

3.5 - 7.5 pmol/L

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Thyroid peroxidase (TPO) is an enzyme expressed mainly in the thyroid where it is secreted into colloid. TPO oxidizes iodide ions to form iodine atoms and then allows the formation of thyroxine (T4) or triiodothyronine (T3) through the addition of iodine molecules. What is the TPO autoantibody?

assessment if TPO antibodies are present
TPO antibodies are not present in healthy thyroid
if TPO antibodies are present suggest autoimmune disease (commonly hypothyroidism)

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What is the purpose of thyroid stimulating hormone (TSH) antibody (TRAB) test?

test to assess if patients have antibodies against against the TSH receptor on thyroid gland
healthy thyroids do not have the antibodies
may indicate an autoimmune disease

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When observing a thyroid stimulating hormone (TSH) curve, what can low levels at the end of the curve, observed in the image below suggest in the patient?

thyroid autoantibodies (antibodies that recognise your own tissue and incorrectly target this)
may present as thyroid disease

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When measuring thyroid stimulating hormone (TSH) in a clinical setting, what are the 2 main limitations?

1 - TSH is slow to respond due to pathological changes, so acute not the best measure
2 - TSH test assumes no pituitary pathology, so T3 and T4 need to be tested alongside

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Thyroid peroxidase (TPO) is an enzyme expressed mainly in the thyroid where it is secreted into colloid. TP oxidizes iodide ions to form iodine atoms and then allows the formation of thyroxine (T4) or triiodothyronine (T3) through the addition of iodine molecules. Does a negative TPO autoantibody test and TRAB-TSH (receptor autoantibody) rule out thyroid autoimmune disease?

no, TPO antibodies are intracellular marker making them difficult to measure
CAN be a marker of autoimmune disease and suggest an increased risk of immune disease
a positive test will confirm a diagnosis though

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Are the antibodies that are created against thyroid peroxidase (TPO) and TRAB-TSH (receptor autoantibody) always destructive?

no they can be destructive or stimulatory

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Hypothyroidism is a lack of thyroid hormones and can be primary (thyroid related) or secondary (hypothalamus/pituitary gland) related. Does hypothyroidism always present with symptoms?

- may be no symptoms

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Hypothyroidism is a lack of thyroid hormones and can be primary (thyroid related) or secondary (hypothalamus/pituitary gland) related. What are the 6 most common and severe symptoms that patients with hypothyroidism may present with?

1 - cold intolerance
2 - facial puffiness
3 - dry skin
4 - hair loss
5 - hoarseness
6 - heavy menstrual periods (impaired ovarian follicular development)

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Hypothyroidism is a lack of thyroid hormones and can be primary (thyroid related) or secondary (hypothalamus/pituitary gland) related. The 6 most common and severe symptoms that patients with hypothyroidism may present with include:

1 - cold intolerance
2 - facial puffiness
3 - dry skin
4 - hair loss
5 - hoarseness
6 - heavy menstrual periods

What are the 2 most severe signs, not included above, that in extreme cases patient with hypothyroidism can experience?

bradycardia

- coma or stupor (near unconsciousness)

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In a patient with primary hypothyroidism, why might we see elevated thyroid stimulating hormone (TSH) and lower levels of thyroxine and triiodothyronine (T3)?

thyroid has reduced T3 and T4 secretion
low T3 and T4 means reduced negative feedback to hypothalamus and pituitary gland
hypothalamus and pituitary gland increase stimulation of thyroid through TRH and TSH

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What are some of the most common causes of primary hypothyroidism (affecting the thyroid directly)?

autoimmunity (among most common in UK)
infection (thyroiditis)
drug interactions
congenital hypothyroidism
iodine deficiency
post hyperthyroidism treatment

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In a patient with secondary hypothyroidism (affecting the hypothalamus or pituitary gland), why might we see low levels of thyroid stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3)?

hypothalamus may reduce thyrotropin levels (TRH) and/or pituitary gland may reduce secretion of TSH
lower levels of TSH means less T3 and T4 will be released from the thyroid

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If a patient presents with high levels of thyroid stimulating hormone and lower levels of thyroxine (T4) is this likely to be a primary or secondary hypothyroidism disorder and what blood test can be performed to confirm this?

- primary - thyroid autoantibodies (TPO or TSH receptors) blood tests - Hashimoto disease is the most common autoimmune disease

What is the key treatment approach for a patient with hypothyroidism?

- increase thyroxine (T4) | - ensure thyroid stimulating hormone (TSH) levels remain at normal levels

The key treatment approach for a patient with hypothyroidism is to increase thyroxine (T4), whilst ensuring thyroid stimulating hormone (TSH) levels remain at normal levels. What is the main treatment used for hypothyroidism?

- levothyroxine, also known as L-thyroxine | - synthetic version of thyroxine (T4)

The key treatment approach for a patient with hypothyroidism is to increase thyroxine (T4), whilst ensuring thyroid stimulating hormone (TSH) levels remain at normal levels. The main treatment used for hypothyroidism is levothyroxine, also known as L-thyroxine, a synthetic version of thyroxine (T4). What is the normal dosage in >65 or those with ischaemic heart disease and <65 years of age?

- <65 ears of age = 1.6μg/kg (approximately 100-150 μg daily) - >65 years of age and/or ischaemic heart disease = 25-50ug/day - FINE TUNING IS REQUIRED THOUGH

The key treatment approach for a patient with hypothyroidism is to increase thyroxine (T4), whilst ensuring thyroid stimulating hormone (TSH) levels remain at normal levels. The main treatment used for hypothyroidism is levothyroxine, also known as L-thyroxine, a synthetic version of thyroxine (T4). Why is it important to fine tune the correct dose of levothyroxine?

- too much levothyroxine means high levels of T4, which have negative feedback loop - this may cause reduced secretion of TSH from pituitary gland, further accentuating hypothyroidism

Hyperthyroidism is an over active thyroid. What are the most common symptoms of hyperthyroidism?

- unintentional weight loss (even if appetite and intake remains constant) - tachycardia - arrhythmia - palpitations - increased appetite - nervousness, anxiety and irritability.

Hyperthyroidism is an over active thyroid. What are the most common sign of hyperthyroidism hat can be seen clinically?

- tremor - warm and moist skin - tachycardia - brisk reflexes - eye signs - thyroid bruit - muscle weakness - atrial fibrillation

In patients with hyperthyroidism, what might we be able to see in the neck, as per the image below?

- enlarged neck | - goiter (abnormal thyroid growth)

What is Graves disease, that affects 20% of patients?

- autoimmune disease - likely to be due to TSH receptor antibodies - causes a form of hyperthyroidism

What is thyroid eye disease (TED) also known as thyroid associated ophthalmopathy (TAO)?

- inflammation of all orbital tissues except the eye (muscle, eyelids, conjunctiva) - causes itchy dry eyes - prominent eyes, called exophthalmos/proptosis

Thyroid eye disease (TED) also known as thyroid associated ophthalmopathy (TAO) is common in graves disease which causes hyperthyroidism. This can cause loss of sight and/or diplopia. What does diplopia mean?

- diplo = double - opia = eye - seeing double due to eye muscles being affected

Thyroid eye disease (TED) also known as thyroid associated ophthalmopathy (TAO) is common in greaves disease which causes hyperthyroidism. This can cause an inability of what in the patients?

- TSH is present in the eyes - hyperthyroidism can cause build up of glycoproteins in the eyes - build up of glycoproteins weakens the eye muscles - patients are unable to close the eyes

Loss of colour vision, redness and swelling of the conjunctiva and itching and pain behind the eyes can all be caused by what? (in relation to thyroids)

- thyroid eye disease (TED) also known as thyroid associated ophthalmopathy (TAO) - build up of glycoproteins in the tissue surrounding eyes - graves disease which causes hyperthyroidism

What disease accounts for 75% of autoimmune caused hyperthyroidism?

- graves disease

Graves disease accounts for 75% of autoimmune caused hyperthyroidism. What happens in graves disease to cause hyperthyroidism?

- autoantibody (IgG) binds to the TSH receptor on the follicular thyroid epithelial cells - autoantibody (IgG) mimics the stimulatory action of TSH - TSH then causes hyperthyroidism

Graves disease accounts for 75% of autoimmune caused hypethyroidism. Autoantibody (Ig) binds to the TSH receptor on the follicular thyroid epithelial cells, mimicking the stimulatory action of TSH, causing hyperthyroidism. What can this then cause to the size of the thyroid?

- hypertrophy and hyperplasia of the thyroid gland | - goitre

In a patient with graves disease, which accounts for 75% of autoimmune caused hyperthyroidism. If we do a dadioiodine uptake test, what can we see on imaging in a patient with graves disease (GD) and a healthy patient?

- GD will have high uptake of iodine to synthesis T3 and T4 | - thyroid will also be enlarged

What is toxic adenoma in relation to the thyroid?

- toxic refers to over production of T3 and T4 | - adenoma = non-cancerous tumor or benign growth

What is the difference between graves disease, toxic adenoma and multiple nodular goitre in relation to the thyroid?

- graves disease = increased levels of T3 and T4 throughout thyroid - toxic adenoma = individual nodule growth on thyroid - multiple nodular goitre = multiple nodular growths on thyroid

Thyroiditis is the inflammation of the thyroid gland. What is De Quervain's (subacute) thyroiditis and what causes this?

- a painful swelling of the thyroid gland | - linked with viral infections

Thyroiditis is the inflammation of the thyroid gland. What is Postpartum thyroiditis and what causes this?

- a woman's thyroid gland becomes inflamed after having a baby - can cause hyperthyroidism and then hypothyroidism - caused by temporary autoimmune reaction

Thyroiditis is the inflammation of the thyroid gland. What is acute/infection thyroiditis and what causes this?

- acute bacterial infections lead to inflammation of the thyroid - can be treated if you address the bacterial infection with antibiotics

If a patient presents with low levels of thyroid stimulating hormone (TSH) and high levels of thyroxine (T4) and triiodothyronine (T3), is this likely to be hyperthyroidism or hypothyroidism?

- high levels of T3 and T4 cause negative feedback on pituitary gland reducing TSH - despite low TSH there is still elevated T3 and T4 - so hyperthyroidism (primary)

If a patient presents with low levels of thyroid stimulating hormone (TSH) and high levels of thyroxine (T4) and triiodothyronine (T3) as measured through blood tests, this is likely to be hyperthyroidism rather than hypothyroidism. What is a likely cause of this?

- graves disease, an autoimmune disease causing hyperthyroidism - high levels of T3 and T4 are secreted, causing a negative feedback look and inhibiting TSH - despite inhibition of TSH, T3 and T4 remain high due to graves disease

If a patient presents with low levels of thyroid stimulating hormone (TSH) and high levels of thyroxine (T4) and triiodothyronine (T3) as measured through blood tests, this is likely to be hyperthyroidism caused by Graves disease. How can we confirm the diagnosis of graves disease?

- measure autoantibodies in blood for Thyrotropin Receptor Antibody Test - may also see goiter (enlarged thyroid gland)

A bruit is an abnormal sound generated by turbulent flow of blood in an artery due to either an area of partial obstruction. Why might we hear this in a patient with hyperthyroidism?

- hyperthyroidism may cause goiter (enlarged thyroid) - enlarged thyroid will have increased vascular presence - the bruit may be heard over the thyroid

What are the 3 main things that can happen if a patient with graves disease, a form of hyperthyroidism is not treated promptly?

- symptoms may escalate - atrial fibrillation - osteoporosis

Patients with graves disease a form of hyperthyroidism can present with a number of clinical symptoms and signs. What cardiac drug can be used to treat patients if they are not asthmatic?

- propanalol a beta blocker | - slows tachycardia caused by hyperthyroidism

If we are treating patients with hyperthyroidism we may choose to prescribe drugs. What are the 2 key drugs that we need to know for the treatment of hyperthyroidism?

1 - Propylthiouracil 2 - Carbimazole - BOTH drugs inhibit thyroid peroxidases, meaning T3 and T4 cannot be produced through iodination in colloid

- inhibition of thyroid peroxidase (TPO) - TPO oxidises iodide to iodine and assists in adding iodine to thyroglobulin in the colloid to create thyroxine (T4) and triiodothyronine (T3) - overall reduces T3 and T4

If we are treating patients with hyperthyroidism we may choose to prescribe drugs. The 2 key drugs that we need to know for the treatment of hyperthyroidism are Propylthiouracil and Carbimazole. These 2 drugs are able to inhibit thyroid peroxidase (TPO), which is responsible for oxidising iodide to iodine and adding iodine to thyroglobulin in the colloid to create thyroxine (T4) and triiodothyronine (T3). What is the normal course of treatment for these drugs?

- 18-24 months (prevents relapse) - start with a high (carbimazole) and reduce the dose as thyroid function settles - or continue high (carbimazole) and then add thyroxine (T4)

If we are treating patients with hyperthyroidism we may choose to prescribe drugs. The 2 key drugs that we need to know for the treatment of hyperthyroidism are Propylthiouracil and Carbimazole. These 2 drugs are able to inhibit thyroid peroxidase (TPO), which is responsible for oxidising iodide to iodine and adding iodine to thyroglobulin in the colloid to create thyroxine (T4) and triiodothyronine (T3). These drugs are normally prescribed for between 18-24 months to prevent relapse. What % of patients will achieve long term cure?

- 30%

Hyperthyroidism can be treated with radioactive Iodine 131 radiotherapy, which has a half life of 8 days. How does this treatment work?

- destroys tissue via B radiation | - concentrated in the thyroid as it uptake iodine

Hyperthyroidism can be treated with radioactive Iodine 131 radiotherapy, which has a half life of 8 days. This treatment works by destroying tissue via B radiation, and is concentrated in the thyroid as it uptake iodine. What are 3 important things patients must be aware of when starting treatment?

1 - they are radioactive to others for 2 weeks 2 - they may set airport security alarms off 3 - could be risk of long term hypothyroidism

In addition to medications and radiotherapy, patients may undergo surgery to treat the hyperthyroidism. What are the 2 surgeries that patients can have done?

- total or partial thyroidectomy

In addition to medications and radiotherapy, patients may undergo surgery to treat the hyperthyroidism. Patients can have 2 surgeries, total or partial thyroidectomy. However, what must patients be prior to surgery?

- euthyroid (normal thyroid function) | - important for clinical outcomes post surgery

In addition to medications and radiotherapy, patients may undergo surgery to treat the hyperthyroidism. Patients can have 2 surgeries, total or partial thyroidectomy, but what are some of the associated risks of this surgery?

- anaesthetic and neck scar - hypothyroidism - hypoparathyroidism - vocal cord palsy (recurrent laryngeal - nerve damage)

Thyroid eye can be quite serious, what are some treatment options for this?

- immunosuppressive - steroid/steroid-sparing - agents - radiotherapy - surgery

What is a thyroid storm, also known as thyrotoxic crisis, most commonly observed in graves disease?

- significant magnification of symptoms associated with elevated thyroid hormones for example T3 is able to: 1 - speed up the basal metabolic rate 2 - more proteins may be produced and more energy in the form of sugars and fats is burnt off, cells essentially going into hyperdrive 3 - T3 increases cardiac output 4 - stimulate bone resorption - thinning out the bones 5 - activates the sympathetic nervous system

Thyroid storm, also known as thyrotoxic crisis, most commonly observed in graves disease is when there is a significant magnification of symptoms associated with elevated thyroid hormones. Where T3 is able to do the following, but in a much more accentuated version than normal: 1 - speed up the basal metabolic rate 2 - more proteins may be produced and more energy in the form of sugars and fats is burnt off, cells essentially going into hyperdrive 3 - increases cardiac output (tachycardia, arrhythmias, heart failure 4 - stimulate bone resorption - thinning out the bones 5 - activates the sympathetic nervous system (GI issues) 6 - result in ICU and high mortality Which patients are likely to get this?

- patients with graves disease who are undiagnosed | - patients with graves disease, but not compliant with treatment

1 - pregnancy 2 - surgery 3 - acute severe illness essentially graves disease with some form or trigger

What is the difference between thyrotoxicosis (toxic levels of thyroid hormones in the blood) and thyroid storm, also known as thyroid or thyrotoxic crisis (dangerous and significant increase in symptoms caused by hyperthyroidism)?

- thyrotoxicosis - a common endocrine condition, generally secondary to a number of underlying processes - thyroid storm represents the severe end of the spectrum of thyrotoxicosis and is characterised by compromised organ function

Thyroid Disease Flashcards

(66 cards)