Thyroid Flashcards
What is the function of the thyroid gland?
Regulates metabolism
Long bone formation
Neural development
Affects bodies sensitivity to catecholamines
What is the blood supply to the thyroid gland?
Superior and inferior thyroid artery which are branches of aorta
How does the thyroid a regulator of metabolism ?
Secretes T3 and T4
Which one out of t3 and t4 is active and which one is the precursor?
T3 active
T4 precursor
What does the thyroid secrete more of, t3 or t4?
T4
20:1 ratio
How much more time potent is t3 than t4?
3/4
Which hormone regulated the production of the thyroid hormones?
TSH from any pit
Where does the thyroid develop from?
Foramen cecum
Where are the thyroid hormones produced?
Follicular cells
What are the causes of hyperthyroidism?
Graves’ disease
Toxic MNG
Pregnancy
What is the most common cause of hyperthyroidism?
Graves
What are the feature of hyperthyroidism?
Weight loss Too hot Goitre Eye symptoms : exophthalmos Palpitations Increase vowel Tremor on hands Tachycardia
What do the investigations show for hyperthyroidism ?
Serum TSH suppressed
Serum free t3/t4 elevated
Ultrasound scan shows nodule and can consider isoptope scan to differentiate
What is the treatment for hyoerthyroidism?
Block and replace: Carbimazole and thyroxine
Dose titration: carbinmazole and propylthiouracil
Radioactive Iodine
Surgery : if failed medical treatment
What nerve do you need to be careful of in thyroid surgery?
Recurrent laryngeal
What is the side effect of carbimazole?
Neutropenia so take FBC if ulcers and sore throat
If uncontrolled they can have thyroid storm
What are the causes of hypothyroidism ?
Primary : thyroid gland and most commonly Autoimmune (hashimoto) and radioiodine therapy for hyperthyroidism
Sedondary : pituitary gland which does not secrete enough TSH due to being damaged from tumour, radiation or sugery. 5-10% of cases
Tertiary: hypothalamus fails to produce enough TRH. This accounts for less than 5% of cases.
What are the features for hypothy?
Weight gain Too cold Tiredness Constipation Thinking hair
What do the tests for hypo show?
TSH elevated
How do you manage hypothyroidism?
Avoid GA and opioid analgesics due to risk of myxodema coma
Risk of anaemia and IHD
Thyroxine tabs
What is a goitre?
Non specific swelling of thyroid
What are the causes of a goitre?
Autoimmune Physiological Iodine def Thyroiditis Nodules
What investigations would you do for a goitre?
Thyroid function test
Chest x ray
Uptake scan
FNAC
What are the symptoms of a thyroid nodule?
Aesthetic
Pain
Pressure
Hormone dysfunction
When would you do surgery ok a thyroid nodule?
Compression More than 5cm Retrosternal Cancer risk Cosmetic
Thyroid nodules can be…
Solitary or part of a MNG
What investigations care carried out in nodules?
Thyroid status and cytology
What are the causes of solitary nodules?
Colloid Cyst Carcinoma Adenoma Lymphoma
What are the sinsiste features of a nodule?
Rapid growth
Hoarse voice
Hx of previous radiation
T/F the thyroid is covered in a sheath?
T
Internal and external layers
What is the external layer of spthyroid sheath connected to?
Anteriorly with pretracheal fascia
Posteriorly with carotid sheath
