Thyroid Flashcards
Where is the thyroid gland located?
Anterior aspect of the neck inferior to the cricoid cartilage
What is the anatomy of the thyroid gland?
Isthmus connects the 2 lobes of the thyroid gland
Fibrous septa divide the gland into pseudo gout composed of follicles
Where does the thyroid gland develop from?
Floor of the pharynx
+
Descends to location giving rise to the Thyroglossal duct
What hormones are produced by the thyroid gland?
What is the main substance needed to produce them?
T3
T4
Iodine
How do thyroid hormones circulate around the body?
Thyroid binding globulin (TBG)
Albumin
TTH
Free circulating
What is hyperthyroidism?
When thyroid gland produces too much T3 and T4
What are the different types of hyperthyroidism?
Primary hyperthyroidism
Secondary hyperthyroidism
Subclincal hyperthyroidism
Graves
Toxic multi Nodular goitre
What is a primary hyperthyroidism?
Where the thyroid gland produces too much T3 T4 independant to the pituitary gland
What is secondary hyperthyroidism?
When too much TSH is being produced leading to the thyroid gland making too much T3 and T4
(Hypothalamus/pituitary issue)
Is there normally more T3 or T4 in the body?
T4
What are the TSH, T3 and T4 levels in a patient with primary hyperthyroidism?
TSH - Extremely low/undetectable
T4 - Very high
T3 - High
What are the TSH, T3 and T4 levels in a patient with secondary hyperthyroidism?
TSH - High
T4 - High
T3 - High
What are the TSH, T3 and T4 levels in a patient with subclinical hyperthyroidism?
TSH - Low
T4 - normal
T3 - normal
What are the symptoms of hyperthyroidism?
Palpitations
Sweaty
Shaking
Weight loss
Diarrhoea
Agitation
Dysmenorrhoea
Heat intolerance
What are the signs of hyperthyroidism?
Tachycardia
AF
Tremor
Hyperkinetic
Palmar erythema
Congestive heart failure
Chorea
Psychosis
Goitre
What are some signs of hyperthyroidism specific to graves?
Ophthalmology signs like exophthalmos
Dermropahy (thyroid acropachy)
Lymphoid hyperplasia
Pretibial Myxoedema
What are some causes of hyperthyroidism?
Graves’ disease
Solitary toxic thyroid nodule
Toxic multi Nodular goitre
Thyroiditis
TSH secreting adenoma
Exogenous thyroid hormones
What is the pathophysiology of Graves’ disease?
Auto antibodies attach to TSH receptors making the thyroid produce lots of T3 and T4 since it thinks theres lots of TSH in the body
What specific features does Graves’ disease have that other hyperthyroidisms dont?
Diffuse non Nodular goitre
Thyroid acropachy (hand swelling and finger clubbing)
Pretibial Myxoedema
Exophthalmus (graves eye disease)
How is Graves’ disease initially managed?
Carbimazole first line
If pregnant give PTU
B blockers for symptom relief (Propranolol)
How is Graves’ disease managed if the patient relapses following treatment?
Consider radioiodine or surgery
What its thee pathophysiology behind a singular toxic thyroid nodule?
Single thyroid nodule = benign adenoma which secretes T3 and T4
How is a solitary/singular thyroid nodule treated that’s causing hyperthyroidism?
Surgical removal
What is the management for a toxic multi Nodular goitre causing hyperthyroidism?
Carbimazole but consider radioiodine or surgery sooner since more likely to relapse than graves
How does Thyroiditis affect the thyroid gland?
Typically get a hyperthyroidism then ultimately a hypthyroidism picture
What is De Quervains thyroiditis?
Subacute thyroiditis which leads to temporary inflammation of the thyroid gland
What is the pathophysiology of De Quervains Thyroiditis?
Hyperthyroidism / thyrotoxicosis occurs due to inflammation
Then hypothyroidism
Then normal
What is the management for De Quervains Thyroiditis?
Symptomatic management since self resolves
NSAIDs for. Any pains
Propranolol for symptoms
Levothyroxine for hypothyroidism
How is a secondary hyperthyroidism treated?
Transphenoidal surgery
Pituitary radiotherapy
What is a thyroid storm?
Severe case of hyperthyroidism / thyrotoxicosis
How does a thyroid storm present?
Severe hyperthyroidism
Ferber
Tachycardia
Delirium
How is a thyroid storm managed?
Endocrinologist:
PTU 200-300mcg/6hrs via NG or Carbimazole
B blockers like propranolol
60mg Prednisolone
Fluid resus
Anti arrhythmias if needed
What is a side effect/adverse reaction of Carbimazole?
Acute pancreatitis
Agranulocytosis
What is a side effect/adverse drug reaction to PTU (Propylthiouracil)?
Agranulocytosis
Severe liver reactions
What are the consequences of having thyroid surgery?
On levothyroxine for life
Risk in surgery:
-bleeding
-anaesthetic risk
-risk vocal cord palsy
What are the precautions that need to be taken when treating a patient with radioactive iodine for hyperthyroidism?
Women must not be pregnant/breast feeding within 6months of treatment
Men shouldn’t father children within 4 months of treatment
Limit contact with children and pregnant woman after dose
What is subclinical hyperthyroidism?
T4 and T3 are normal but TSH has become low
What are the symptoms of hypothyroidism?
Fatigue
Weight gain
Lethargy
Constipation
Cold intolerance
Amenorrhoea
Dry skin
Hoarse voice
Carpal tunnel
Depression
What are the signs of hypothyroidism?
Bradycardia
Heart block
Odema
Dry skin + nails
Hyporeflexia
What are the 2 types of hypothyroidism?
Primary hypothyroidism
Secondary hypothyroidism
What is primary hypothyroidism?
What is secondary hypothyroidism?
Primary = Thyroid produces abnormally low T3 and T4 despite high TSH
Secondary = pituitary makes low TSH so thyroid makes low T3 and T4
What are some causes of primary hypothyroidism?
Hashimotos thyroiditis
Iodine deficiency
Hyperthyroidism treatments (Carbimazole, PTU, radioiodine and surgery)
Lithium
Amiodarone
What are some causes of secondary hypothyroidism?
Pituitary adenoma
Pituitary surgery
Radiotherapy
Sheehans syndrome
Trauma
What 2 causes of hypothyroidism can cause a goitre?
Hashimotos Thyroiditis
Iodine deficiency
How is hypothyroidism managed?
Life long levothyroxine
Build up dose gradually (1.6mcg-1.8mcg/kg)
TSH every 6 weeks then annually
How must levothyroxine be taken?
1st thing in morning on empty stomach 30mins before food or other meds
What conditions affect the absorption of levothyroxine?
Coeliacs
H-pylori
Lactose intolerance
What is a Myxoedema coma?
Severe hypothyroidism
How is a Myxoedema coma managed?
ABCDE
Passive external. Warming. 0.5degrees/hr
Thyroid hormone replacement - T4 300-500 mcg IV or. NG then 50-100mcg/day
If no improvement in 24-48hrs consider giving T3
