Diseases of the Endocrine System Flashcards
What is the role of the endocrine glands?
What is paracrine and autocrine secretion?
endocrine glands secrete hormones directly into the blood stream and act systemically
paracrine system secretes hormones that act locally
autocrine secretion affects the cell secreting the protein
Where is the pituitary gland situated?
What does it weigh?
situated in the sella turcica beneath the hypothalamus
it weighs between 500 - 1000 mg
What are the 2 parts of the pituitary gland?
anterior:
- 75% of the gland is formed by the anterior lobe
- this is formed by an outpouching of the oral cavity (Rathke’s pouch)
posterior:
- 25% of the pituitary gland is the posterior lobe
- this is formed by downgrowth of the hypothalamus
What is adenohypophysis?
it is another term for the anterior part of the pituitary gland
What is meant by neurohypophysis?
another term for the posterior lobe of the pituitary gland
it stores and releases oxytocin and vasopressin produced in the hypothalamus
What are the different causes of anterior pituitary hypofunction?
- tumours - non-secretory adenoma, metastatic carcinoma
- trauma
- infarction
- inflammation - granulomatous, autoimmune, other infections
- iatrogenic
What are the majority of primary pituitary tumours?
What causes the effects of the tumour?
the vast majority of adenomas are benign
they may be derived from any hormone producing cell
if functional, the clinical effect is secondary to the hormone being produced
local effects are due to pressure on the optic chiasma or adjacent pituitary
What are the 3 different types of anterior pituitary adenoma?
prolactinoma:
- this is common
- causes galactorrhoea and menstrual disturbance
growth hormone secreting:
- causes gigantism in children and acromegaly in adults
ACTH secreting:
- Cushing’s syndrome
What is the anatomy of the thyroid gland like?
How much does it weigh?
bilobed organ joined by an isthmus encased in a thin fibrous capsule
it is located at the level of the 5th, 6th and 7th vertebrae in the anterior neck and in close proximity to the trachea
What is the weight of the thyroid gland?
average weight is 18g in adult males and 15g in adult females
What are the anatomical relationships of the thyroid gland?
abuts the thyroid cartilage of the larynx
the recurrent laryngeal nerve is located in the tracheo-oesophageal groove close to the posterior aspect of the lateral lobes
Label the diagram
Label the diagram
What is the origin of the thyroid gland like?
it has 2 parts
the main part migrates from the foregut to the anterior neck
the ultimobranchial body forms in branchial arches and fuses with the main bit laterally
What does the remnant of the thyroid gland in the foregut form?
foramen caecum
this is at the junction between the anterior 2/3 and posterior 1/3 of the tongue
What is Hashimoto’s?
(chronic lymphocytic thyroiditis)
Who is more commonly affected?
an autoimmune chronic inflammatory disorder associated with diffuse enlargement and thyroid autoantibodies
it is more common in females
peak age is 59 years
What happens in Hashimoto’s disease?
there is a diffusely enlarged non-tender gland
lymphocytic infiltration of thyroid parenchyma, often with germinal centre formation
many patients become hypothyroid
What clinical feature is raised in Hashimoto’s?
What are the increased risks associated with this condition?
serum thyroid antibodies are elevated
there is an 80 fold increased risk of thyroid lymphoma
there is an increased risk of papillary carcinoma of the thyroid
What is diffuse hyperplasia (Graves’ disease)?
Who tends to be more affected?
an autoimmune process results in clinical hyperthyroidism and diffuse hyperplasia of the follicular epithelium
it is more common in females
peak in third and fourth decades
What are the physical findings in Graves’ disease?
- pretibial myxoedema
- hair loss
- wide-eyed stare or proptosis
- tachycardia
- hyperactive reflexes
What are the signs of Graves’ disease?
What clinical marker will be elevated?
the thyroid is diffusely enlarged
T3 and T4 will be elevated
TSH will be suppressed
There will be thyroid autoantibodies, especially thyroid stimulating immunoglobulin
What is meant by multinodular goitre?
enlargement of the thyroid with varying degrees of nodularity
1 or more thyroid nodules discovered by a patient or health care provider
What are the signs of multinodular goitre?
What may it be mistaken for?
most patients are euthyroid
the dominant nodule may be mistaken clinically for thyroid carcinoma
large nodules may cause tracheal compression or dysphagia
What does euthyroid mean?
having a normally functioning thyroid gland
What is follicular adenoma?
Who does it usually affect?
benign encapsulated tumour with evidence of follicular cell differentiation
it affects more females
there is a wide age range, usually from fifth to sixth decade
What are the symptoms of follicular adenoma?
How is it usually detected?
painless neck mass, often present for years
there is a solitary nodule involving only one lobe
it is usually cold nodule on radioactive iodine imaging
What are the different types of malignant tumours of the thyroid?
- differentiated thyroid carcinoma
- medullary carcinoma
- anaplastic carcinoma
- malignant lymphoma