ChemPath - Thyroid

Question 1

What are the normal values for TFTs

Answer 1

TSH: 0.33-0.45
T4: 10.2-22
T3: 3.2-6.5

Question 2

What are the causes of hypothyroidism

Answer 2

Raised TSH
Hashimoto’s
Atrophic hypothyroidism
De Quervains Thryoiditis
Riedel thyroiditis
Iodine deficiency (most common WW)
Drug-induced e.g. lithium, antithyroid drugs, post-partum

Low TSH
TSH secreting tumour
Thyroid hormone resistance

Raised TSH (T4/T3 normal)
Subclinical hypothyroidism
Treated hypothyroidism

Question 3

What are the features of Hashimoto’s thryoiditis

Answer 3

Painless goitre in elderly females
May initially be a toxicosis
Anti-TPO antibodies
Hurthle cells

Question 4

What are the features of atrophic hypothyroidism

Answer 4

Most common cause in the UK
Diffuse lymphocytic infiltration → atrophy
small thyroid (no goitre)
Associated with pernicious anaemia/vitiligo/endocrinopathies

Question 5

What are the features of Riedel’s thryoiditis

Answer 5

Dense fibrosis replacing the normal parenchyma
Painless, stony hard thyroid

Question 6

What are causes of hyperthyroidism

Answer 6

Suppressed TSH
Graves disease
De Quervains thyroiditis
Plummer’s disease
Drugs e.g. amiodarone
Ecotpic tumours e.g. Struma ovarii, trophoblastic tumour (HCG)

Low TSH and T4/T3
Pituitary cause

Suppressed TSH, normal T3/T4
Subclinical hyperthyroidism

Question 7

What are the features of Graves disease

Answer 7

Autoimmune
40-60%
F > M (9:1)
Painless goitre
Anti-TSH receptor antibodies
High diffuse uptake on isotope scan

Question 8

What are the features of Plummer’s

Answer 8

High uptake
Hot nodules
Painless, enlarged
Distended follicular cells with colloid + flattened epithelium

Question 9

What are the features of De Quervain’s thryoiditis

Answer 9

Self-limiting
Post viral infection
Goitre
Hyperthyroid then hypothyroid

Question 10

What is the management for hypothyroidism

Answer 10

thyroid replacement (thyroxine)

Question 11

What is the management for hyperthyroidism

Answer 11

Symptom relief: beta blockers, topicals steroids, eye drops for eye disease
Antithyroid:
- Carbimazole
- PTU
Radio-iodine
Surgery

Question 12

What are the regimens for anti-thyroid medications

Answer 12

Titration: start low, increase
Block and replace: cause hypothyroidism then replace with levothyroxine (high risk of SEs: agranulocytosis, rash)

Question 13

Describe the use of radioiodine in hyperthyroidism

Answer 13

Good efficacy for primary treatment, sometimes used after medical therapy has failed
Risk of permanent hypothyroidism
Contraindicated in pregnancy and lactating women

Question 14

What are the indications for thyroidectomy

Answer 14

Women intending to become pregnant in the next 6/12
Local compression secondary to thyroid goitre (oesophageal/tracheal)
Cosmetic
Suspected cancer
Co-existing hyperparathyroidism
Refractory to medical therapy

Question 15

What are the types of thyroid cancer

Answer 15

Papillary
Follicular
Medullary
Anaplastic

Question 16

What are the features of papillary thyroid cancers

Answer 16

most common (75-85%)
Painless cervical lymphadenopathy, no obvious clinical
abnormality of thyroid
Tumour marker: Thyroglobulin
Spread: Lymph nodes and lung
Histology: Psammoma bodies (foci of calcification), emptyappearing nuclei with central clearing (Orphan Annie eyes)

Question 17

What are the features of follicular thyroid cancers

Answer 17

Well-differentiated but spreads early
Tumour marker: Thyroglobulin
Spread: Blood&raquo_space; lungs, bone, liver, breast, adrenals
Histology: Fairly uniform cells forming small follicles,
reminiscent of normal thyroid

Question 18

What are the features of medullary thyroid cancer

Answer 18

Associated with MEN2
Neuroendocrine neoplasm derived from parafollicular C
cells secreting calcitonin
Tumour marker: CEA, calcitonin
Histology: Sheets of dark cells, amyloid deposition within
tumour (calcitonin broken down to amyloid)

Question 19

What are the features of anaplastic thyroid cancer

Answer 19

Early and wide metastases common
Spread: very aggressive à local, lymph nodes, blood
Histology: Undifferentiated follicular, large pleomorphic giant
cells, spindle cells with sarcomatous appearance

Question 20

What conditions are in MEN1 and what is the inheritance

Answer 20

Autosomal dominant

Pituitary
Pancreatic (insulinoma)
Parathyroid

Question 21

What conditions are in MEN2a and what is the inheritance

Answer 21

Autosomal dominant

Parathyroid
Phaeochromocytoma
Medullary thyroid

Question 22

What conditions are in MEN2b and what is the inheritance

Answer 22

Autosomal dominant

Phaeochromocytoma
Medullary thyroid
Mucocutaneous neuromas & marfanoid