Week 3 - C - Week 3 - Thyroid gland pathology Flashcards
What is the weight of the thyroid gland?
25-30g
What is the evagination from which the thyroid gland develops and how does it travel to the anterior neck?
The thyroid gland develops from an evagination of the developing pharyngeal epithelium that descends as part of the thyroglossal duct from the foramen cecum at the base of the tongue to its normal position in the anterior neck.
When the thyroid gland fails to fully descend, and ectopic thyroid tissue arises at the base of the tongue, what is this known as?
Lingual thyroid
Does lingual thyroid normally require treatment? What is a disadvantage of surgery?
Does not normally require treatment and surgery can render the patient hypothyoird
What are the round structures containing the thyroglobulin containing colloid?
Follicles
What are the cells located within the follicle known as?
follicular cells
What are the cells located in the thyroid which secrete calctionin? What does an increase in calcitonin caus?
These are the parafollicular cells (C cells)
Calcitonin causes a decrease in blood calcium levels
How does parathyroid hormone increase blood calcium level from bone? vs How does calcitonin decrease blood calcium levels from bone?
PTH increase osteoclast activity leading to breakdown of bone and calcium release into the blood
Calcitonin lowers blood calcium levels by suppressing osteoclast activity in the bones and increasing the amount of calcium excreted in the urine
What are the large purple objects? What are the small dark purple cells? What are the cells that are intermediate size?
Large purple are colloid Follicular cells Parafollicular cells (C cells)
What is the release of hormones from hypothalamus to thyroid?
Thyrotropin releasing hromone (TPH) is released from the hypothalamus stimulating the release of thyroid stimulating hormone (TSH) from anterior pituitary which when acting on the follicular cell causes the release of T3 and T4 into the bloodstream
Tropic hormones are hormones that have other endocrine glands as their target. Name at least 2 of the four tropic hormones of the anterior pituitary gland?
follicle-stimulating hormone (FSH) luteinizing hormone (LH), adrenocorticotropic hormone (ACTH) and thyroid-stimulating hormone (TSH).
TSH binds to TSH receptor on surface of thyroid epithelial cell (follicular cell), how does this binding cause the release of T3 and T4?
The binding of TSH cause the activation of Gproteins converting GTP to GDP and the production of cAMP cAMP increases the production and release of T3 and T4
What is 85% of hyperthyroidism due to?
85% due to Grave’s disease
What are two potential other causes of hyperthyroidism? (one is to do with ovaries)
TSH secreting pituitary adenoma Struma ovarii - a rare ovarian tumour which may cause hyperthyroidism (contains mostly throid tissue)
Polymorphisms in immune regulation associated genes can cause an under/over active thyroid Polymporphisms in what two genes can make you more susceptible to thyroid dysnfunction? (the two genes appear to be involved in many autoimmune conditions according to articles online)
CTLA4 gene and PtPN22 gene
If the patient has hyperthyroidism symptoms and is above or below 40, what do you think?
Below 40 - grave’s disease Above 40- multi-nodular goitre
What is the main group of antibodies in grave’s disease known as?
Anti-TSH receptor antibodies (anti-Trabs)
What are the three anti-TSH antibodies? Which can cause hypothyroidism?
Thyroid stimulating immunoglobulin Thyroid growth stimulating immunoglobulin TSH binding inhibitory immunoglobulin - this can cause hypothyroidism as it blocks the binding of TSH
What is the triad of features in graves’ disease?
Hyperthyroidism - diffuse enlargement of the thyroid gland Exopthalmos Preitibial myxoedema
What are the majority of cases of hypothyroidism due to?
Hashimoto’s thyroditis
What are the haplotypes associated with ashimoto’s thyroditis?
HLA-DR3 and HLA DR5
What are other ways in which you can get hypothyroidism?
Iodine deficiency Iodine excess - needs to be high excess Drugs such as lithium and amiodarone