1. By Joshua Bower Easter Revision 2014 J.Bower@warwick.ac.uk
THYROID

2. What hormones does the thyroid gland produce?
Thyroxine (T4)
Tri-iodothyronine (T3)
Calcitonin

4. List the SIX steps in thyroid hormone synthesis [6]
Thyroglobulin synthesised from tyrosine
Uptake and concentration of iodide
Oxidation of iodide to iodine
Iodination of thyroglobulin
Coupling of 2 iodinated tyrosine molecules to form T4 or T3
Secretion

5. Thyroid Hormone synthesis (3)
Follicular Lumen
(COLLOID)
Blood
Thyroglobulin chain (tyrosine residues)
Thyroglobulin synthesis
pendrin
Iodide (I-)
iodine(Io)
TPO
NIS
MIT and DIT
mono-, di-iodotyrosine
Conjugation MIT and DIT T3 and T4
TPO - thyroid peroxidase
NIS – sodium-iodide symporter
hydrolysis
Secretion T3 & T4
Follicle cell

6. Describe the HPT axis

7. How do thyroid hormones travel?
70% bound to thyroxin binding globulin (70%)
30% bound to albumin
TBG has higher affinity for T4 – readily available reserve

8. Which hormone is the active one?
T4 is converted by deiodinases to T3, to bind to T3R and have an effect

9. List FOUR physiological actions of TH [4]
Affects BMR
Maturation and differentiation of bone, lung, brain etc
Synapse formation
Myelinogenesis
Neuronal outgrowth
Growth (regulated by GH, but needs T3/T4)

10. By what week of development does the foetus make its own T3/T4?
After trimester 1, not enough TSH or T4/T3 can cross placenta

11. What is cretinism?
Impaired physical and neurological development due to iodine deficiency during foetal or postnatal development
Irreversible after first 2 years of life
TSH levels tested for in heel prick test

12. List THREE signs/symptoms of hyperthyroidism [3]

13. What would the blood test results show in hyperthyroidism?
Inc’d T3/T4
Inc’d TSH (if fault in or above pituitary gland)
Dec’d TSH (if fault with thyroid gland)

14. What is Grave’s disease?
Auto-antibody (TSI) for the TSH receptor
Causes hyperthyroidism
Causes goitre as TSI is stimulating thyroid gland, even if TSH levels low

15. List THREE signs/symptoms of hypothyroidism [3]
Slow
Lethargic
Overweight/obese
Alopecia
Goitre

16. What would the blood test results show in hypothyroidism?
Dec’d T3/T4
Inc’d TSH (usually)

17. List THREE possible treatments for thyroid issues [3]
Drugs (inhibit production or replace hormone)
Radioactive iodine (131I) to destroy gland
Surgery

18. List THREE complications associated with thyroid gland surgery [3]
General surgery issues
Vocal cord nerve damage
Bleeding
Parathyroid gland damage

19. By Joshua Bower Easter Revision 2014 J.Bower@warwick.ac.uk
QUESTIONS?