Flashcards in Thyroid pathology Deck (93):
What are the three embryological abnormalities of the thyroid gland?
Lingual thyroid gland
Thyroglossal duct cyst
Retrosternal thyroid gland
How is the thyroid gland arranged histologically?
Follicles containing thyroglobulin and lined by follicular epithelium
Scattered C cells/parafollicular cells
What do C cells secrete?
What does calcitonin do?
Reduces blood calcium levels (minimally relevant)
Which thyroid-related hormone is secreted from the hypothalamus to act on the anterior pituitary?
Thyrotropin releasing hormone
Which thyroid-related hormone is secreted from the anterior pituitary to act on the thyroid?
Thyroid stimulating hormone
Which hormones are secreted from the thyroid in response to hormonal stimulation from the pituitary?
Which specific cells of the thyroid does thyroid stimulating hormone act on?
Thyroid follicular epithelium
Which receptor does thyroid stimulating hormone bind to? Where is this receptor found?
TSH receptor on follicular epithelium
Which type of receptor is TSH receptor?
G-protein coupled receptor
How do G-protein coupled receptors work?
Convert GTP to GDP to produced cAMP which increases the production of thyroid hormones
T3 and T4 only circulate when bound to plasma proteins. T/F
False - they exist in bound or free forms
How do T3/4 work on target tissues?
Bind to target cells >
Bound T3/4-receptor complex translocates to the cell nucleus >
Binding to thyroid response elements on target genes >
Gene transcription and increase in BMR
When might the thyroid gland atropy?
When its function is reduced
Enlarged thyroid glands are capable of causing breathing and/or swallowing difficulties. T/F
True - if thyroid glands enlarge enough they can cause local mass effects
Define the terms thyrotoxicosis and hyperthyroid
Thyrotoxicosis - too much thyroid hormone
Hyperthyroid - hyper function of the thyroid tissues
Is there a genetic component to autoimmune thyroid disease?
What autoimmune condition is associated with autoimmune thyroid disease?
What is the most common cause of hyperthyroidism?
What is a pituitary cause of thyrotoxicosis?
TSH secreting pituitary adenoma
Name a cause of ectopic thyrotoxicosis
Grave's disease is autoimmune. T/F
Is graves disease more common in woman or men?
What age group typically presents with Grave's disease?
What are the antibodies against in Grave's disease?
Thyroid stimulating hormone receptor
Name an anti TSH receptor antibody involved in Grave's
Thyroid stimulating immunoglobulin
What is the triad of features found in Grave's disease?
Hyperthyroidism with diffuse goitre
Why do you get thryoid eye disease in Grave's?
Fibroblasts within the eye and surrounding tissues express TSH receptors
What is the most common cause of hypothyroidism?
Is hashimoto's thyroiditis autoimmune?
Who typically gets Hashimoto's thyroiditis?
Middle aged woman
Is Hashimoto's thyroiditis associated with other autoimmune conditions? Is it associated with HLA?
Yes & yes
What are secondary and tertiary causes of hypothyroidism?
What are other causes of hypothyroidism?
Iatrogenic (hyperthyroidism treatment)
Is hashimoto's thyroiditis more common in woman or men?
What is the typical age range who gets hashimoto's thyroiditis?
Does hashimoto's thyroiditis have a genetic component?
What anti-thyroid antibodies are associated with hashimoto's thyroiditis?
What is hashitoxicosis?
Transient hyperthyroidism that can precede hashimoto's thyroiditis
Which two things is hashimoto's thyroiditis associated with?
B cell non-hodkin's lymphoma
What is a goitre?
Enlargement of the thyroid gland
Which dietary deficiency is goitre/goitre-producing conditions associated with?
What is the typical pathogenesis of goitre?
Reduced thyroid hormones >
TSH increased and results in enlarged gland >
How does a hypothyroid goitre occur?
Compensation for reduced thyroid hormone fails resulting in hypothyroid goitre
What is the term for a state of normal thyroid hormone levels?
Doe males or females get diffuse goitre more commonly?
Why might adolescents/young adults present with diffuse goitre?
Dyshormonogenesis (errors of metabolism)
How do young patients with diffuse goitre typically present?
Euthyroid with mass effect symptoms (subclinical hypothyroid)
What may dyshormonogensis' cause in children?
Can multi-nodular goitre evolve from a long standing diffuse goitre?
What mass effects can goitre cause?
What is the risk of malignancy with a multinodular goitre?
Low but present
Which cells do follicular and papillary thyroid carcinomas come from?
Which cells does medullary thyroid carcinoma come from?
Parafollicular C cells
How do follicular adenomas present?
Discrete solitary mass +/- local symptoms if large
Are thyroid adenomas functional?
Most are not
Those which are most often cause hyperthyroid (TSH independent)
What is follicular adenoma often mistaken for?
Dominant nodule in multinodular goitre
Do males or females more commonly get thyroid cancer?
Females (apart from children and elderly)
When do thyroid cancers present?
What is papillary cancer associated with?
What is follicular cancer associated with?
What is medullary cancer associated with?
Multiple endocrine neoplasia type 2
Familial medullary cancer
What type of goitre does papillary cancer cause?
Solitary thyroid nodule - multifocal, cystic, calcified
Does papillary cancer spread by lymph or blood?
Does follicular cancer spread by lymph or blood?
How does papillary cancer typically present?
What type of goitre does follicular cancer cause?
Slowly enlarging, painless, solitary nodule
Where does follicular cancer tend to spread?
Bones, lungs, liver
What age group typically gets follicular cancer?
How common is medullary thyroid cancer?
What can medullary thyroid cancers secrete?
In which scenario would a medullary cancer arise in a 1) young patient and 2) an adult?
1 - MEN
2 - Familial/sporadic
What is the difference between sporadic and familial medullary cancer cases?
Sporadic - solitary nodule
Familial - bilateral/multicentric
How does medullary cancer present?
What causes paraneoplastic 1) diarrhoea and 2) cushings?
1 - VIP
2 - ACTH
What is the most aggressive thyroid cancer?
In which age range does anaplastic cancer present?
Which cancer occurs in people with a history of thyroid cancer?
How is thyroid cancer classified?
Th1 - repeat test
Th2 - benign
Th3 - atypia probably benign
Th4 - atypia probably malignant
Th5 - malignant
How many parathyroid glands are there?
Which cells compose the parathyroid glands?
Chief cells and oxyphil cells
What do chief cells secrete and what is its effect?
Parathyroid hormone affecting calcium metabolism
What is the most common cause of hyperparathyroidism?
What is parathyroid hyperplasia associated with?
Multiple endocrine neoplasia 1 & 2
What is the difference in terms of gland involvement between parathyroid adenomas and hyperplasia
Adenoma - one gland involved and others atrophic
Hyperplasia - all glands involved
What chronic metabolic state can cause secondary hyperparathyroidism?
What are the two most common causes of chronic hypocalcaemia?
Vitamin D deficiency
What is tertiary hyperparathyroidism associated with?
What is the presentation of hyperparathyroid disease?
Bone (pain, fracture, osteoporosis)
Nephrolithiasis (kidney stones)
GI complications (constipations, nausea, gall stones)
Neuromuscular (weakness, fatigue)
CVS (calcification of aortic and mitral valves)
How common is hypoparathyroid?
What are the common causes of hypoparathyroid?
Di George syndrome (congenital)
What are the associations with familial hypoparathyroidism?