ChemPath - Thyroid Flashcards
What are the normal values for TFTs
TSH: 0.33-0.45
T4: 10.2-22
T3: 3.2-6.5
What are the causes of hypothyroidism
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
What are the features of Hashimoto’s thryoiditis
Painless goitre in elderly females
May initially be a toxicosis
Anti-TPO antibodies
Hurthle cells
What are the features of atrophic hypothyroidism
Most common cause in the UK
Diffuse lymphocytic infiltration → atrophy
small thyroid (no goitre)
Associated with pernicious anaemia/vitiligo/endocrinopathies
What are the features of Riedel’s thryoiditis
Dense fibrosis replacing the normal parenchyma
Painless, stony hard thyroid
What are causes of hyperthyroidism
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
What are the features of Graves disease
Autoimmune
40-60%
F > M (9:1)
Painless goitre
Anti-TSH receptor antibodies
High diffuse uptake on isotope scan
What are the features of Plummer’s
High uptake
Hot nodules
Painless, enlarged
Distended follicular cells with colloid + flattened epithelium
What are the features of De Quervain’s thryoiditis
Self-limiting
Post viral infection
Goitre
Hyperthyroid then hypothyroid
What is the management for hypothyroidism
thyroid replacement (thyroxine)
What is the management for hyperthyroidism
Symptom relief: beta blockers, topicals steroids, eye drops for eye disease
Antithyroid:
- Carbimazole
- PTU
Radio-iodine
Surgery
What are the regimens for anti-thyroid medications
Titration: start low, increase
Block and replace: cause hypothyroidism then replace with levothyroxine (high risk of SEs: agranulocytosis, rash)
Describe the use of radioiodine in hyperthyroidism
Good efficacy for primary treatment, sometimes used after medical therapy has failed
Risk of permanent hypothyroidism
Contraindicated in pregnancy and lactating women
What are the indications for thyroidectomy
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
What are the types of thyroid cancer
Papillary
Follicular
Medullary
Anaplastic
What are the features of papillary thyroid cancers
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)
What are the features of follicular thyroid cancers
Well-differentiated but spreads early
Tumour marker: Thyroglobulin
Spread: Blood»_space; lungs, bone, liver, breast, adrenals
Histology: Fairly uniform cells forming small follicles,
reminiscent of normal thyroid
What are the features of medullary thyroid cancer
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)
What are the features of anaplastic thyroid cancer
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
What conditions are in MEN1 and what is the inheritance
Autosomal dominant
Pituitary
Pancreatic (insulinoma)
Parathyroid
What conditions are in MEN2a and what is the inheritance
Autosomal dominant
Parathyroid
Phaeochromocytoma
Medullary thyroid
What conditions are in MEN2b and what is the inheritance
Autosomal dominant
Phaeochromocytoma
Medullary thyroid
Mucocutaneous neuromas & marfanoid
