Week 3 - E - Week 3 - hypo/hyper thyroidism and thyroiditis, sick-euthryoid Flashcards
Autoimmune thyroid disease is the commonest cause of primary hyper and hypo thyroidism Where do the causes for secondary hypo and hyper thyroidism arise?
Primary hypo/hyperthyrodisim is due to a problem with the thyroid gland
Secondary hypo/hyperthyroidism - They arise due to problems in the hypothalamus or the pituitary gland
When measuring hromones to test for thyroid disease, what are the hormone levels in overt (clincal) hyperthyroid disease?
TSH - low
T4/T3 - high
When measuring hormones to test for thyroid disease, what are the hormone levels in overt (clincal) hypothyroid disease?
TSH - high (compensting for low T4/T3)
T4/T3 - low (failing thyroid gland)
What are the hormone levels in both secondary hypo and hyper thyroidism?
Hyperthyroidism - TSH is high and T4/T3 is high
Hypothyroidism - TSH is low and T4/T3 is low
What is one cause of secondary hyperthyroidism? (thyrotropinoma) What is one cause of secondary hypothyroidism?
Secondary hyperthyroidism - a rare pituitary tumour that secretes TSH - known as a TSH oma (or thyrotropinoma)
Secondary hypothyroidism - pituitary gland failure
What is the difference between overt (clinical) and subclinical thyroid disease?
Overt thyroid disease is defined as the clincal syndrome with associated hormones elevated and decreased
Subclinical thyroid disease is defined as thyroid hormones (T3/4) within normal range however TSH out of the normal range
* there may or may not be symptoms of thyroid disease
In subclincial hypo/hyper thyroidism, what are the hormone levels?
Hypothyroidism - TSH is high with T4/3 normal
Hyperthyroidism - TSH is low with T4/3 normal
Why are the thyroid hormone levels normal in subclinical hypo or hyper thyroidism?
In sublcinical hyperthyroidism - the T4 and T3 hormone levels are rising however still within the normal range and therefore the TSH levels falls in an attempt to prevent this
In subclincal hypothyroisim, the thyroid hormone levels are falling within the normal range and TSH increases in an attempt to prevent overt hypothyroidims
What is the term used synonymously with severe hypothyroidism but also refers to the dermatological changes that can occur in hypothyroidism?
Myxoedema
What causes myxoedema? How does it appear on a person?
accumulation of mucopolysacchardies in connective tissue of dermis causing swelling of the skin and underlying tissues giving a waxy consistency
What is the most severe form of hypothyroidism? What are its features?
Myxoedema coma - the body temperature is usually abnormally low
sparse, dry hair, and loss of the outer thirds of the eyebrows;
difficulty breathing;
significant swelling (edema) all over the body with swollen eyes and thickening of the tongue,
Form of thyroid dermopathy in grave’s disease seen on anterior aspect of the shin?
Pretibial myxoedema
Aspect of Grave’s disease characterized by soft-tissue swelling of the hands and clubbing of the fingers?
Thyroid acropachy
What is the most common cause of primary hypothyroidism? (in the western world) What defieciency can lead to hypothyroidism? (can also be due to excess of this mineral)
hashimoto’s thyroidits (autoimmune thyroiditis)
(worldwide iodine deficiency is the most common cause)
Iodine deficiency
What is the most common drug induced form of hypothyroidism?
Amiodarone
Secondary cause of hypothyroidism caused by an infilrative disease What is this disease?
Sarcoidosis
What is a secondary cause of thyroid disease which can occur due to women who lose a life-threatening amount of blood in childbirth or who have severe low blood pressure during or after childbirth, which can deprive the body of oxygen?
This condition is known as Sheehan syndrome - where excessive blood loss in childbirth can deprive the body of oxygen.
This lack of oxygen that causes damage to the pituitary gland
It results in panhypopituitarism - ‘pan’ referring to all pituitary hormones being affected
Which antibody is most commonly raised in people suffering from hypothyroidism?
Anti-thyroid peroxidase antibodies (Anti-TPO)
What is another autoimmune condition that may be present in those with Hashimotos disease? A cutaneous conditions
Vitiligo
What are symptoms of hypothyroidism in the eyes and hair? What can hypo do to heart failure? (what is the symptom)
Eyes - periorbital puffiness
Hair- dry and coarse
Hypothyroidism can worsen heart failure causing pitting oedema
What does hypothyroidism do to the metabolism and what does this cause?
Slows the metabolism and decreases basal metabolic expenditure
It decreases the appetite however still causes a weight gain usually
Due to the swelling caused by hypothyroidism, what syndrome can this cause in rare cases associated with nerve compression?
Carpal tunnel syndrome
Hypothyroidism can cause oligo/amenorrhea How does hypothyroidism cause galactorrhea?
Hypothyroidism will give feedback loops causing TRH to secrete more TSH
however TRH also causes the release of prolactin and therefore due to the rise in prolactin, galactorrhea may occur
In treating hypothyroidism, what medication and dosage should the patient be started on?
Younger patients: start thyroxine at 50-100 μg daily
In the elderly with a history of IHD: start thryroxine at 25-50 μg daily
How long should the thyroxine be continued for? Once the TSH levels have stabilised, how often should they be checked?
Thyroxine should be continued for life
Checked every 12-18months
When may dose requirement of thyroixne be increased and why?
Thyroid requirements increase during pregnancy and therefore increase there thyroxine dose –
makes sure there is no foetal brain abnormalities due to low thyroid hormones
As it is the tissue thyroid activity that shows whteher the thyroid hormone levels are low, this causes the feeback to signal whether less or more TSH is needed Therefore is it better to monitor primary hypothyroidism by measuring TSH or T4?
Measuring TSH
Also measuring T4 in subclincal hypothyrodism will give you a false postiive
When is T4 used to montior thyroid disease prgression?
Secondary hypothyroidism
TSH is not a useful index of therapeutic success – it will remain low if T4 therapy is commenced
If T4 levels are normal and TSH levels are still very high in hypothyroidsm, what could cause this?
Patient could have taken thyroixne tablet shortly before arriving for blood tests and this is therefore a false positive for a functioning thyroid
Typically affects elderly women with long standing but frequently unrecognized or untreated hypothyroidism What is this?
Myxoedema coma
Type II respiratory failure is a finding in myxoedema coma, what are finding on an ECG?
bradycardia, low voltage complexes, varying degrees of heart block,
T wave inversion, prolongation of the QT interval
What are the symptoms of hyperthyrodism? Cardiac Sympathetic Vision Metabolism
Cardiac - palpations, atrial fibrillation
Sympathetic - sweating and tremor
Vision - lid lag, lid retraction and exopthalmos in graves
Metabolism - weight loss even though increased appetite
What is the first and second most common causes of hyperthyroidism? What age groups?
Main cause of hyperthyroidism is Grave’s disease
Second most common is Nodular thyroid - Multi-Nodular Goitre – usually above age 50
If younger than age 50 then most likely Grave’s disease is the cause
Grave’s disease is more common in females than male, what antibodies are found in grave’s? (main one and the other two)
Anti-TSH receptor antibody (TRAbs – TSH receptor antibodies) are the broad group name
Most commonly is the thyroid stimulating immunoglobulin
(thyroid growth stimulating immunoglobulin and TSH binding inhibiting immunoglobulin also present)
What does grave’s disease show on scintography?
Smooth symmetrical uptake
What drugs are given for Grave’s disease to treat the overactive thyroid and how long are they given for?
Give carbimazole or propylthiouracil
Given for 12-18 months however 50% will relapse
What is the redness of the eye known as in thyroid eye disease? Thyroid eye disease (TED) is the most common extra-thyroidal manifestation of Graves’ disease.
Chemosis
Muscles at the back of the eye become inflamed causing eye to go forward as muscles aren’t as strong What is this known as? What can increase the risk of thyroid eye disease and decrease it if stopped?
Exopthalmos
Stop smoking
In nodular thyroid disease, the gland can feel bumpy What the the hormone tests show? What does antibody tests show? What does scintigraphy show?
T4/T3 high,
TSH low
Antibody negative
Asymmetrical uptake on scintigraphy
What is a single nodule, in thyroid nodule disease known as?
Dominant nodule or toxic adenoma
What is the opposite side of the spectrum from myxoedema coma known as? Can cause Respiratory and Cardiac Collapse Hyperthermia Exaggerated reflexes May require Ventilation
Thyroid storm
What is the emergency treatment of thyroid storm?
Slow the heart rate, reduce T4 to T3 activation, treat the precipitant
* Beta blocker
* IV dexamthasone / hydrocortisone - blocks peripheral conversion of T4 to T3
* Carbimazole or propylthiouracil to reduce T4 to T3 conversion (propylthiouracil also decreases peripheral conversion)
* Iodine - blocks release of existing hormone (Lugol’s iodoine)
What anti-thyroid medication can cause agranulocytosis? What is agranulocytosis?
Carbimazole
a deficiency of granulocytes in the blood, causing increased vulnerability to infection. no neutrophils
What are the symptoms of agranulocytosis where the patient is told to stop taking the drug immediately and phone the GP?
Sudden fever
Mouth ulcers
Sore throat
Bleeding gums
Why is propothiouracil not 1st line for hyperthyroidism? When is it used?
Propylthiouracil is usually not used first-line, due to a small risk of severe liver injury,
except in certain circumstances such as pre-pregnancy or the first trimester of pregnancy as carbimazole is teratogenic at this time
In treating patients with hyperthyrodism with radio iodine, what precautions should be taken before and after? How long should preganncy be avoided? (radio-iodine is a pill that is swallowed and absorbed into the bloodtream)
Ensure not Pregnant
Avoid close prolonged contact with young children/pregnant women
Don’t share a bed for x days
Avoid Pregnancy for 6 months
What is a major risk of radio-iodine treatment?
High Risk of Hypothyroidism (esp in Graves)
What are the three main risk of thyroidectomy?
recurrent laryngeal nerve palsy
Hypothyroidism
Hypo-parathyroidism
What is the type of thyroidits that is usually self limiting within 4-6 months?
Sub-Acute Thyroiditis aka De Quervian’s thyroiditis
What is the prgression of Sub-Acute Thyroiditis/ De Quervains?
Initially have an overactive thyroid followed by an underactive thyroid that becomes euthyroid in around 4-6 months
Describe the typical presentation of a patient with De Quervian’s thyroiditis?
Typically presents as a painful swelling of the thyroid gland following a viral illness -
It usually causes fever and pain in the neck, jaw or ear.
Patient initially has symptoms of overactive thyroid which then become underactive symptoms and settle after 4-6 months when hormone levels become normal
What do the hormone tests in dequervians show in early and late testing? What does scintigraphy show?
T4- high in early stage, low in late, then normal
TSH- low in early stage, high in late, then normal
Low uptake
Does amiodarone induced thyrotoxicosis or hypothyroidism occur in areas with a low iodine intake?
Amiodarone induced thyrotoxicosis occurs more frequently in areas with low iodine intake
Amiodarone induced hypothyroidism occurs more frequently in areas with high iodine intake
What is this?
Overt primary hypothyroidism
What is this?
Subclinical hypothyroidism
What is this?
Secondary hypothyroidism - due to a pituitary disorder
What is this and any additional tests?
Primary hyperthyroidism - most likely grave’s Test for antibodies and scintigraphy
What is this and additional tests?
Primary hyperthyroidism - most likely mutli-nodular goitre Test antibodies for negative and scintigraphy
What is this?
Sub-acute thyroiditis - DeQuervians
What is sick euthyroid syndrome? In sick euthyroid syndrome (now referred to as non-thyroidal illness), what are the thyroid hormone levels? What is the treatment?
Euthyroid sick syndrome is a condition in which serum levels of thyroid hormones are low in clinically euthyroid patients with nonthyroidal systemic illness.
Low T3,4 and normal TSH
Changes are reversible upon recovery from the systemic illness and hence no treatment is usually needed.
