At what vertebral level is the thyrod gland found?
C5 - T1
What supplies parasympathetic control to the thyroid gland?
Vagus nervee
What is the arterial supply for the thyroid?
Superior and inferior branches of the thyroid arteries
( branch of the external carotid artery )
What is this stucture called?
A Follicle
What are the cells making up the ring called?
Follicular cells
What is the middle of the ring called and what does it contain?
Collioid thyroglobulin
What ingredient is required to make thyroid hormones?
Iodine
Two DITs makes ….
T4
One MIT and One DIT makes ____?
T3
What percentage of thyroid hormone is thyroxine and what percentage is triiodothyronine ?
90% thyroxine T4
10% Triiodothyronine T3
What thyroid hormone is more potent T3 or T4?
T3 is 4x more potent
What plasma proteins do T3 and T4 bind to?
Thyroxine binding globulin 70%
Thyroxing binding prealbumin 20%
Albumin 5%
What effects do thyroid hormones have on metabolic rate and thermogenesis?
Increase metabolic rate
Increases thermogenesis
What effect do thyroid hormones have on sympathetic action?
Increases responsiveness to adrenaline and sympathetic neurotransmitters.
What stimulates the thyroid and where does it come from ?
Thyroid stimulating hormone from the anterior pituritory gland
What is graves disease?
Autoimmune disease where Thyroid stimulating immunoglobin acts like thyroid stimulating hormone leading to hyperthyroidsism
What 3 hormones does thyroid gland tissue secrete?
Thyroxine (T4)
Tri-iodothyronine (T3)
Calcitonin
What do the parathyroid glands secrete?
Parathyroid Hormone PTH
What veins drain the thyroid gland?
Superior and middle thyoid vein into the internal jugular vein
Inferior thyroid vein into the brachiocephalic vein
How are thyroid hormones regulated?
Thyrotrophin releasing hormone (TRH) from the hypothalmus stimulates the anterior pituitary to release thyroid stimulating hormone. (TSH)
What a patient with an over active thyroid what would be the TSH T4 and T3 levels?
T4/T3 high
TSH low
What would be the TSH T3 and T4 levels in a failing thyroid gland?
TSH high
T4/T3 low
What would the TSH and T3/T4 values be in secondary hyperthyroidism?
TSH high
T3/T4 high
What does Myxoedema mean?
Severe hypothyroidism
or
Skin disease associated with Graves
What is Hashimoto’s hyroiditis?
Autoimmune hypothyroidism
What happens in autoimmune hypothyroidisim?
Autoimmune destruction of the thyroid gland resulting in reduced thyroid hormone production
What is characterisitic of Hashimoto’s thyroiditis?
Presence of Thyroid Peroxidase antibodies
T-cell infiltrate and inflammation on microscopy
What are the facial signs and symptoms of hypothyroidisim?
Coarse, sparse hair
Periorbital puffiness
Loss of outer eyebrows
Peri-orbital puffiness
What is the management plan for hypothyroidisim?
In young patients:- 50-100micrograms
In elderly with ischeamic heart disease:- start at 25-50 micrograms
What happens in Myxoedema coma?
extreme hypothyroidisim
Type 2 respiratory failure
Bradycardia, low voltage complexes, heart block, prolonged QT interval
What happens to the menstral cycle in patients with
(a) hyperthyroidisim
(b) Hypothyroidisim
Hyperthyroidisim - Less frequent and lighter bleeding
Hypothyroidisim - Heavier bleeds
What are the three common causes of hyper-thyroidism?
Graves disease
Nodular thyroid
Thyroiditis
What is the natural progression of graves disease?
after 18 months 50% will “burn out”
50% will relapse
What is responsible for graves disease
Thyroid stimulaing immunoglobulin
What is Thyroid storm?
Severe hyperthyroidisim resulting in respiratory and cardiac collapse
How do you treat hyperthyroidism?
Carbimazole
How do you treat hyperthyroidism in pegnancy?
Propylthiouracil
What is De Quervains Thyroiditis?
Sub-Acute Thyroiditis
What happens in sub-Acute thyroiditis?
T4 is high in early stage , low in late then is normal
TSH componsates accordanly
Can be triggered by viral infection ( Sore throat etc)