The Thyroid

Question 1

TRH

Answer 1

Stimulates TSH release from the anterior pituitary.

Question 2

TSH

Answer 2

Stimulates thyroid hormone production.
Activates iodide uptake via the sodium / iodide symporter (SIS).

Question 3

Triiodothyronine
(T3)

Answer 3

4 x the ‘ strength’ of T4. Increases growth, bone and CNS development, increases BMR, heart rate and activates metabolism

Question 4

Tetraiodo-thyronine (T4)

Answer 4

AKA thyroxine. Approx. 90% of secreted thyroid hormone. Weak ‘thyroid’ activity ——‘inactive’ form.

Question 5

Reverse T3 (RT3)

Answer 5

Biologically inactive protects tissues from
excess thyroid hormones.

Question 6

Nutrients needed for thryoid hormones

Answer 6

• Tyrosine and iodine:
• Iron
• Selenium and zinc:
• Vitamin D
• Vitamins A, B2, B3, B6, B12, C, E
• Copper

Question 7

Excess Iodine

Answer 7

• The Wolff Chaikoff effect helps reject excess iodine and hormone synthesis. The effect is inhibited in certain individuals leading to induced subclinical or clinical hypothyroidism.
• Consumption of over iodised salt, animal milk rich in iodine (fortified),
  iodine containing dietary supplements.
• Radiocontrast dyes; medications (e.g., amiodarone used for heart
  arrythmias and contains iodine).

Question 8

HPT disruptors:

Answer 8

• Pesticides
• PCBs (POPs) and bisphenols (e.g., BPA)
• Phthalates
• Perchlorates (e.g., nitrate fertilisers and food packaging)
  Halogens

Question 9

TSH Range

Answer 9

0.4 to 2.5

Question 10

Thyroid markers

Answer 10

Question 11

Thyroid hormones
testing interpretation

Answer 11