Hypothyroidism

Question 1

What happens to TSH levels in Primary Hypothyroidsim?

Answer 1

Rises

Question 2

What is the main cause of primary Hypothyroidism?

Answer 2

Autoimmune damage to thyroid gland-

Question 3

What are the main symptoms of Primary hypothyroidism?

Answer 3

Features: Feel cold, tired, lethargy, memory impairment, Bradychardia, Hypertension, weight gain, voice deepening, consipation
Respond very well to thyroxine
The worse it can get is comas-usually seen in lonely people or old-as they think its normal

Question 4

Which form of T (3/4) is the active form of thyroxin?

Answer 4

T3 is the much more active form but over 80% of the circulating is T4 form
T4 is like a pro-drug

Question 5

How does T3 impact a cell?

Answer 5

Both T3/4 can enter, but T4 is transformed. T3 acts on heterodimer on DNA and increase gene expression of specific genes. TRE-thyroid receptor

Question 6

What are the different options for thyroid hormone replacement?

Answer 6

Thyxorine sodium-LEvothryxine sodium (T4 form)-usually the drugs of choice
Can give T3 as well, but much more rare

Question 7

When would you use T3 or T4 replacement hormones?

Answer 7

In primary hypothyroidism, where the production isnt working-T4 is perfect
use TSH levels as the guide for the needed levels

For secondary hypo (eg Pit tumour/damage,AID)-T4 given as well-but cant use TSH as guide because isnt made-aim for f(free)T4 in middle of reference range

When patient is in Myxoedema Coma, then give T3-active form-and much faster acting, and can be injected
Conteversy over T3-some patients convinced should only use T3 cause T4 isnt good enough (???)-no proof of that though

Combines thyroid-T3/T4-some reported improved well being, and symptoms of toxicity, and supress TSH (the guide to give the drugs)

Question 8

What are the half lives of T3 and T4 replacements? How much of it is free in the plasma?

Answer 8

T4-6days
T3-2.5 days
=> means for t4 missing a dose is not the worse

99.97% of T4 is bound, 99.7% of T3 is bound-unfree, and only free one can act (bound to Thyroixine binding globulin (TBG)-TBG can fall with malutrition, coadministered drugs

Question 9

What are the two causes of of hyperthyroidism?

Answer 9

Graves’ disease and Nodular Goitre (Plummers disease)

Question 10

What is Graves Disease?

Answer 10

Autoimmune-Antibody stimulates the thyroid gland
causes a smooth Goitre and hyperthyroidism
Hyper-racing heart, jittery, persipation, active brain (then becomes agrressive and cant speak)-Pretibial Myxedma (tissue growth-due to AB increasing that, non pitting), warm, lose weight and increased appetite, diarrhea, Graves opthalmopathy and Exothalamos (caused by other AB-not direct thyroixine) (makes eyes look like staring, and lose/double, etc vision)