Thyroid Flashcards
The thyroid gland is made of 2 triangular lobes which sit between vertebral levels ________ to ______ connected by an isthmus. The isthmus overlies the ____ and ____ Tracheal rings
C5-T1
Overlying 2nd and 3rd tracheal rings
What is the venous drainage of the thyroid gland?
What about LN drainage?
Superior, middle, and inferior thyroid veins
Pre laryngeal
Pre tracheal
Paratracheal LNs
What are the nearby structures to the thyroid which could lead to complications post-op?
Nerves:
External laryngeal nerve (CNX)
Recurrent laryngral nerve (CNX)
Vagus nerve
Arteries: Internal and inferior carotid arteries
Organs: Parathyroid, esophagus, LNs, trachea
What is the function of the external laryngeal nerve?
Where does it lie in relation to the thyroid gland?
Where does the recurrent laryngeal nerve lie in relation to the thyroid gland?
Innervates the cricothyroid muscle
Runs medial to the inferior portion of the thyroid gland
Recurrent laryngeal nerve runs in the groove between the esophagus and trachea medial to the superior portion of the gland
Give the full list of symptoms of hyperthyroidism that you would like to ask in a history
Name each level of LNs and point at where it lies on the neck
Does the thyroid gland produce T3 or T4? Where does that occur in the thyroid gland?
where does the thyroid hormone convert from one form to the other?
When ordering TFTs which one do we look at alongside TSH primarily?
Note that the image in the book is incorrect.
The thyroid follicles in the thyroid gland primarily produce T4 which is the less active pre-cursor hormone
The liver and other peripheral tissues convert T4 to T3
The primary thing we look at is T4 on the TFTs (as thats the one typically circulating before being converted)
What signs would you bee looking for on exam for a patient presenting with symptoms of hyperthyroidism? (you can perform the exam as its the full exam)
What symptoms are you looking to elicit in a history for a patient with hypothyroidism
Idk how youd ask about bradycardia in a history so ignore lol
A patient has given you a history of hypothyroidism is for some reason in the long case. What exam findings would be consistent with it?
What are the borders of the anterior and posterior triangle of the neck?
Anterior:
Midline medial border
Mandible superior border
SCM Lateral borer
Posterior:
SCM medial border
Middle 1/3 of clavicle is inferior border
Trapezius is the posterior border
Give your differentials for a neck mass
Anterior:
Congenital: Branchial Cleft Cyst, Thyroglossal duct cyst,
Inflammatory/Infectious: Grave’s, Multinodular goitre, Hashimoto
Neoplastic: Thyroid malignancy (name if u can), multinodular goitre
Posterior:
Congenital: Cystic Hygroma, Pharyngral pouch
Inflammatory/Infectious: Parotiditis, Parotid LA in deep lobe
Neoplastic: Parotid neoplasm
Anywhere: LA (lymphoma or infectious), Lipoma, Sarcoma Cyst, SCC/BCC/Melanoma
Tip (like how SCM is link between Anterior and posterior, the word cyst separatesthe congenital cause of anterior and posterior)
What conditions initially start off as hyper but eventually become hypo?
De Quervain’s Tenosynovitis (patient with a history of infection and tender)
Post-partym thyroiditis
What is Reidel’s Thyroiditis and how does it present?
It is a rare chronic inflammatory thyroiditis characterised by extensive fibrosis
Presents with stridor and a hard woody swelling (requires resection of isthmus often)
Give your differentials for both hyper and hypothyroidism
Does Iodine deficiency cause a goitre?
Yes, a diffuse goitre
What procedure is performed to treat a thyroglossal duct cyst?
Sistrunk procedure
Involves extension of neck, incision over cyst in skin crease, Hyoid bone split. (just FYI)
What labs are specific for the thyroid?
TFTs (T3, T4, TSH)
Anti-TSH
Anti-Thyroglobulin
Anti-TPO
Give me the TFT results of the following
Hyperthyroidism
Subclinical hyperthyroidism
Drug-related hyperthyroidism
Hypothyroidism
Subclinical hypothyroidism
What is the reason behind using flexible endoscopy when working up a patient with a thyroid mass?
Looking for integrity of the vocal cords and hence the integrity of the recurrent laryngeal nerve
Give 3 ways you can tell there is a recurrent laryngeal nerve injury on a patient
1) Bovine Cough (youtube it)
2) Ask patient to speak (Hoarsness)
3) Nasal endoscopy
Is the CT used for thyroid investigation contrast or non-contrast and why?
Why is CT neck being ordered in the first place (3 things)
Non-contrast as it delays and interferes with radioiodine
It is ordered to assess the degree of expansion including
1) Retrosternal expansion
2) compression of nearby organs and structures such as trachea, esophagus…
3) Lymphadenopathy
Whatre the 3 most important imaging to perform for a patient presenting with a thyroid mass?
US Neck/thyroid
Non-contrast CT
Scintigraphy
What features on ultrasound would be worrying? Give 5 (there are 6)
Micro-calcifications
Irregular margins
Solid
Size >5cm (according to GAMES criteria its >4)
Increased vascularity
Lymphadenopathy
If micro-calcifications are associated with malignancy (common with many cancers btw). Does that mean macro-calcifications are typically benign?
Yes Micro = malignant Macro = benign
What U-score would warrant escalation
What Thy score would warrant escalation?
U4,U5
Thy 3f, Thy4, Thy 5
The Thy score is obtained via what type of biopsy?
FNA (unlike most cancers)
Just like breast, it is graded according to increased suspicion of cancer based on cytological findings. But note that in breast it is a core biopsy and FNA would only be used to determine if cancer is present or not
What are the indications for a thyroidectomy?
4Cs
Cancer
Carbimazole (failed medical tx)
Cosmesis
Compression
Prior to any surgery, patients must be euthyroid. Why?
How do we make a patient euthyroid?
It reduces vascularity of the gland, reducing complications and blood loss
This is done via Lugol’s solution which is (I2 + KI + H2O) very simple
In total what are the thyroid-specific investigations you will perform?
What supportive investigations need to be performed?
Labs (TFTs + Anti TSH, thyroglobulin, TPO)
Flexible endoscopy
US, Non-contrast CT, Scintigraphy
FNA biopsy
Supportive:
ECG essential!
PTH
Calcitonin
ECHOcardiogram
What would an ECG of a patient with Severe hyperthyroidism typically show?
A.fib => irregularly irregular rhythm, fibrillatory waves, absent P waves, shortened QRS
What is Scintigraphy and how is it conducted?
What results does it show?
What results would you expect in the following scenarios?
Grave’s disease:
Toxic Multinodular goitre:
Solitary nodule:
Thyroiditis:
Cancer:
It is a nuclear technitium-based imaging which is conducted using a scintillation probe (large long camera) while measuring background radiation from the thigh
Shows:
Cold spots = reduced uptake
Hot spots = increased uptake
Grave’s disease: Diffuse Hot area
Toxic Multinodular goitre: Patchy uptake
Solitary nodule: Single area of uptake
Thyroiditis: Cold/absent
Cancer: Cold/absent (in areas of cancer)
What is the risk of cancer if scintigraphy shows a cold spot?
10%
If a patient comes with a small thyroid mass. How will you decide if you should take a biopsy or not?
If there is a strong suspicion of cancer from other investigations that overrides this rule
<1cm -> No FNA
>1cm or suspicion => FNA
What is Grave’s Opthalmoplegia?
Cluster of 4 eye signs in Grave’s disease: COPE
Chemosis
Opthalmoplegia
Proptosis
Exopthalmos
Note: Proptosis means bulging out of any organ. Exopthalmos is that specific to the eye. Just go with it
Define Grave’s disease
How does it present?
Autoimmune disease targetting TSH receptors leading to irreversible agonism => hyperthyroidism
Presents as sx of hyperthyroidism + GTP
Grave’s Opthalmoplegia (Chemosis, opthalmoplegia, proptosis, exopthalmos
Thyroid acropachy
Pre-tibial myxoedema
What is the difference between pre-tibial myxoedema and hypothyroid myxoedema
Pre-tibial = grave’s = hyperthyroidism
This is localized oedema under the tibia
Hypothyroid myxoedema is generalized => youll get the rounded face, facial oedema etc…
You send out investigations for grave’s disease specifically. What results will you get back?
+/- scintigraphy showing raised, diffuse uptake
Hyperthyroidism is all managed in the same algorithm. List the steps in the algorithm
1) Beta blocker + Carbimazole/PTU
2) Radioactive iodine
3) Subtotal/total thyroidectomy
What is the role of beta blockers for a patient with hyperthyroidism?
What beta blockers are used for this case?
sx relief (tachycardia, hypertension)
Non-specific beta blockers => Propranolol and Carvidolol
What is the MOA of carbimazole
What is the MOA off PTU
Carbimazole and PTU actually share the same side-effects (to different degrees). What are they?
Carbimazole blocks TPO => blocks T4 synthesis
PTU blocks conversion of T4 ->T3
SE: Teratogenicity, Agranulocytosis (neutropenic sepsis), Hepatotoxicity, Rash, Arthralgia
What does PTU stand for?
What is the relevant strength of carbimazole compared to PTU
Propylthiouracil
Carbimazole is 10x as potent
What is the regime for carbimazole for Grave’s disease?
What should you warn the patient about if theyre taking carbimazole?
Start at high dose and titrate down. Duration of 18 months
If you develop a sore throat or cough seek medical attention (neutropenic sepsis)
The risk of hypothyroidism with radioactive iodine therapy in the management of hyperthyroidism is?
2-5%/yr.
Thyrotoxicosis is a hypermetabolic syndrome due to elevated TH levels. How does it present?
What are the 2 main complications associated with this?
How will you work up the patient while performing your ABCs?
How will you treat a patient presenting to the ED with thyrotoxicosis?
Once the acute episode is over what else can we do?
Presents with hyperthyroidism but they cannot COPE with their sx
Chemosis
Opthalmoplegia
Proptosis
Opthalmoplegia
Complications:
A-fib => stroke, TIA, Limb ischaemia, ischaemic colitis, renal artery emboli…
Osteoporosis (very rapid metabolism)
Workup: ECG + labs -> US -> scintigraphy
Tx:
ABC + 10 steps
!!Beta blocker - Propranolol
Anticoagulation - LMWH/DOAC/Warfarin
High dose carbimazole (to later be tapered down)
If thyroiditis => Steroids may have a role
Later:
Give Calcichew, and refer for DEXA and osteoporosis workup
Radioactive iodine/lovectomy if needed
List All the types of thyroid cancer as you would in a long case
Must include how it is monitored for.
1) Well differentiated - Measured with thyroglobulin
a) Papillary (80%)
b) Follicular (10%) -> Hurthle cell, insular
2) Poorly differentiated - Calcitonin
a) Medullary TC (4%)
b) Anaplastic (2%)
Patient with high thyroglobulin and not encapsulated. What cancer is most likely?
What on histology would confirm the diagnosis?
How does this cancer tend to spread?
Would it more likely metastasise to bone or lung?
Papillary Ca is not encapsulated and well-differentiated (=> thyroglobulin)
Half of Papillary Ca will have Psammona bodies on histology
This cancer tends to spread by lymphatics (if its not encapsulated => hydrophobic) => lung
Patient with high thyroglobulin and encapsulated. What cancer is most likely?
What on histology would confirm the diagnosis?
How does this cancer tend to spread?
Would it more likely metastasise to bone or lung?
Follicular Ca is encapsulated and is well differentiated
Histology will show colloid (which is also a prognostic factor)
Spreads haematogenously (if its encapsulated => hydrophilic => can go in blood) => bone
What does calcitonin do?
Reduces calcium => facial flushing and diarrhoea
Define Medullary TC
What % are genetic? What is the gene? What other cancers are associated with someone who has this?
How would this patient present?
Other than calcitonin what other tumour marker may be present?
It is a neuroendocrine tumour of the parafollicular C-Cells which produce Calcitonin (other tumour marker is CEA).
80% are sporadic while 20% are associated with MEN2 (A and B) and hence should be evaluated for other MEN 2 which are phaochromocytoma, parathyroids, and neuromas (around the body)
Presents with mass + Facial flushing + diarrhoea
What does calcitonin do?
Reduces calcium => facial flushing and diarrhoea
What is the management of anaplastic TC?
Palliative care
Why is there no hope for those with anaplastic TC and only palliative care?
It proliferates so fast that they will die before carbimazole has any effect
There are no Na/I symporters => radioactive iodine will not help. they also typically present with metastasis => no curative surgery
What are the 4 main RF for thyroid cancer?
What score is used for the prognosis of thyroid cancer. Go through it
After a total thyroidectomy, patients are basically hypothyroid. What is the post-op regimen given to all patients (and hence also the tx regime for hypothyroidism)?
Note that it says OD but when fine-tuning regimens its nice to note that some people will have days off where they dont take the medication instead of changing the strength of medication
What should you tell patients who are taking levothyroxine
1) strict adherence especially if on regimen requiring a cumulative weekly dose.
2) educate on symptoms of hyperthyroidism and safety netting if those occur
3) Take in the morning on an empty stomach at least 30 minutes before taking other foods or medications as it can affect absorption
4) Take the medication in an upright position with a cup of water
Why do patients with heart disease require a smaller dose of levothyroxine?
what additional medication is given to them for those cases?
Can provoke angina => beta blocker (propranolol) if needed
Give me the full workup for a patient presenting with a mass up until cure
What are the specific complications post-thyroidectomy?
Late = Permanent hypoparathyroidism
How are the following Post-thyroidectomy complications managed?
1) Strap haematoma
2) Hypocalcaemia
