Thyroid Pathologies

Question 1

Describe what the thyroid looks like in Graves disease?

Answer 1

Enlarged
Increased vascularity
Columnar follicular cells
Increased number and size of follicular cells.

Question 2

What is Graves disease?

Answer 2

An autoimmune disorder where autoantibodies bind to TSH receptor and over stimulate it.

Question 3

Which autoantibodies are commonly detectable in Graves?

Answer 3

TRAB (TSH receptor antibodies)

TPO (Thyroid Peroxidase antibodies).

Question 4

Give examples of conditions that Graves is associated with?

Answer 4

Other autoimmune disorders

T1DM, Vitiligo, Percutaneous Aneamia.

Question 5

Describe Graves symptoms?

Answer 5

Weight loss 
Anxiety 
Diarrhoea 
Amennorhea 
Tremor 
Tachycardia 
Flushed 
Goitre 
Opthamology

Question 6

Describe Graves ophthamology?

Answer 6

Seen in 50% of sufferers.
Imflammation and oedema of the extraoccular muscles.
Lymphocytes enter periorbital tissues and activate fibroblast which secrete osmotically active hyaluronic acid.
Causes lid retraction, proptosis and diplopia.

Question 7

What investigations would be done for suspected graves disease?

Answer 7

Iodine123: Radioactive isotope given orally or by IV injection and it is taken up by the thyroid gland. Can use Xray to see where it it accumulates.
Lots in one area - adenoma.
Lots all over - Graves.

Question 8

Describe thyroid hormone levels seen in Graves?

Answer 8

Descreased TSH

Increased T3/T4.

Question 9

Describe Drug treatment of graves?

Answer 9

B-Blockers: To treat symptoms of tachycardia and hypertension.

Carbizamole and Propylthiouracil: Prevent Thyroid Peroxidase from coupling and iodinating tyrosine. Both can cause agranulocytosis (low WCC) so cant be used with infection. Can also cause puritis/rash.

Carbizamole is a prodrug converted to thiamazole via first pass metabolism, it also has immunosuppresive effects. Side effects: rash, nausea, vomiting, joint aches, skin apalasia.
Propylthiouracil is less active and has a shorter half life than carbizamole so a larger dose is needed. It also stops T4 conversion to T3 at periphery. Side effects: Hepatic necrosis, cant use in pregnancy 1st trimester.

Question 10

Describe other treatments of Graves?

Answer 10

131 Iodine: Is radioactive and accumulates in thyroid and destroys gland by local radiation.

Total or subtotal thyroidectomy - if cant use 131 and drug resistant.

Question 11

Describe causes of hyperthyroidism?

Answer 11

Adenoma, thyroiditis, Graves, toxic multinodular goitre.

Question 12

Describe symptoms of hypothyroidism?

Answer 12

Fatigue 
Weight gain 
Cold 
Dry hair/skin 
Goitre 
Constipation 
Menorrhagia 
Depression 
Bradycardia

Question 13

Describe Thyroid hormone levels in primary hypothyroid?

Answer 13

TSH high, T4 low

Question 14

Describe thyroid hormone levels in secondary hypothyroid?

Answer 14

TSH low, T4 low.

Question 15

Name causes of primary hypothyroidism?

Answer 15

Hashimotos, thyroiditis, Iatrogenic

Question 16

Name causes of secondary hypothyroidism?

Answer 16

Pituitary disease.

Question 17

Describe hashimotos?

Answer 17

An autoimmune thyroid disease.
Get high Anti-TPO antibodies and lymphoid infiltration of the gland.
Initially an increase in hormone levels as it is released, then chronic decrease do to atrophy and fibrosis of the gland.
May be genetic, more common in females.

Question 18

What are reasons for thyroiditis?

Answer 18

Viral, inflammation, post-partum.

Question 19

What are reasons for iatrogenic hypothyroid?

Answer 19

Post-thyroidectomy, post 131Iodine radiotherapy, after drugs containing lithium.

Question 20

What is endemic goitre?

Answer 20

Goitre associated with chronic iodine deficiency.

Not common in UK.

Question 21

What is sick euthyroid?

Answer 21

When ill patients have low thyroid hormones. Probably a normal physiogical response to illness to conserve energy.
Get low TSH and low T4.

Question 22

How is hypothyroidism treated?

Answer 22

Levothyroxine: Taken orally on an empty stomach. It is synthetic thyroxine. Dose is slowly increased over months as it varies for people, and must cardiac monitor.
T4 falls quickly but takes TSH around 6 weeks to fall.

Question 23

What should you avoid when taking levothyroxine?

Answer 23

Calcium supplements, iron supplements and PPI’s as they may interefere with levothyroxine absorption.

Question 24

Why does it take thionamides around 10 days to have an effect?

Answer 24

As T4 has a half life of around 7 days