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
What is the most commonest type of thyroid carcinoma?
What people are most commonly affected?
papillary carcinoma
female predominance is 2.5:1
it has a wide age range mean of 43 years
What is papillary carcinoma?
What conditions is it associated with?
familial, autosomal dominant non-medullary thyroid carcinoma
seen in FAP and Cowden’s syndrome
treated by therapeutic irradiation
What genetically causes papillary carcinoma?
activation of RET or NTRK1
this is caused by a variety of chromosomal translocations or inversions
fusion of RET tyrosine kinase regions with constitutively expressed thyroid proteins
BRAF V600E mutation
RAS mutations
What is the macroscopic appearance of papillary carcinoma like?
- ill defined, infiltrative
- some encapsulated
- may be cystic
- granular
What are the 5 different types of follicular neoplasms?
- follicular adenoma
- minimally invasive follicular carcinoma
- widely invasive follicular carcinoma
- hurthle cell neoplasms
- Ras mutations
WHat % of thyroid cancers are follicular carcinomas?
How do patients present?
10-20% of all thyroid cancers
90% present with a solitary nodule in the thyroid
10% present with distant metastasis
What is the difference between a minimally invasive and widely invasive follicular carcinoma?
minimally invasive < 5% metastasis
widely invasive is > 60% metastasis
What is Hurthle cell carcinoma?
Who does it usually affect?
accounts for 3% of all differentiated thyroid carcinomas
the median age is 53 (range of 24 - 85 years)
sex ratio of F:M is 7 : 3
What is the clinical behaviour of Hurthle cell carcinoma?
What are the most common haematogenous sites?
unlike follicular carcinoma there is a significant incidence of cervical lymph node metastases
common haematogenous sites are bone, liver and lung
What is primary hyperparathyroidism?
excessive secretion of parathyroid hormone from one or more glands
What is meant by secondary hyperparathyroidism?
hyperplasia of glands with elevated PTH in response to hypocalcaemia
this is from renal insufficiency, malabsorption or vitamin D deficiency
What is meant by tertiary hyperparathyroidism?
this occurs in association with longstanding secondary hyperparathyroidism
What is the incidence of primary hyperparathyroidism?
25-28 cases per 100,000 population
Caucasian women over 60 - 190/100,000
What is the pathogenesis of primary hyperparathyroidism?
- aging, tumorigenesis in general
- association with ionising irradiation
- MEN 2a
What is primary hyperparathyroidism associated with?
- asymptomatic
- arterial hypertension
- psychiatric problems
- hypercalcaemia
- decreased renal function
- osteoporosis
- hyperparathyroid bone disease
- hypercalcaemia symptoms
- urolithiasis
What malignancies is primary hyperparathyroidism associated with?
- single adenoma - 85-90%
- diffuse chief or clear cell hyperplasia - 10-15%
- carcinoma - 1%
What is parathyroid adenoma?
How many people does it affect and how does it present?
an encapsulated benign neoplasm of parathyroid cells
it affects 1 per 1000 people
it presents with symptoms of hypercalcaemia
What is parathyroid adenoma associated with?
associated with MEN1 and MEN2 syndrome , hyperparathyroidism and jaw tumour syndrome
it involves a single enlarged parathyroid gland
all the other remaining glands are suppressed and small
What is secondary and tertiary hyperparathyroidism?
In what patients is it common?
non-neoplastic increase in parathyroid parenchymal cell mass within all parathyroid tissue with a known stimulus
it is common in patients with renal failure and on dialysis
it has identical pathological features to primary hyperplasia and may be associated with massive gland enlargement
What is parathyroid carcinoma?
What are the symptoms related to?
malignant tumour derived from parathyroid parenchymal cells
symptoms are referable to excess calcium
How is parathyroid carcinoma treated?
What is the survival like?
it is indolent with recurrences common (about 50% of cases)
treated with surgery
50% of cases have 10-year survival
Label the adrenal gland
What is Cushing’s syndrome?
a collection of signs and symptoms due to prolonged exposure to cortisol
paraneoplastic Cushing’s is seen in small cell lung carcinoma
What are the endogenous and exogenous causes of Cushing’s syndrome?
exogenous causes:
- excessive glucocorticoid medication
endogenous causes:
- adrenal cortical tumours
- adrenal cortical hyperplasia
- ACTH secreting pituitary adenoma
What are the signs and symptoms of Cushing’s syndrome?
- hypertension
- moon face
- central obesity
- buffalo hump
- weak muscles
- osteoporosis
- insomnia
- excessive sweating
- mood swings
- headaches
- chronic fatigue
Women may have increased hair growth (hirsuitism) and irregular menstruation
What is Conn’s syndrome?
hyperaldosteronism - primary and secondary
more common in women and those 30-50 years old
excess production of the hormone aldosterone by the adrenal cortex leads to low renin levels
this is controlled by the renin-angiotensin system
What are the symptoms and signs of Conn’s syndrome?
- high blood pressure
- headache
- muscular weakness
- muscle spasms
- excessive urination
- cardiac arrhythmias
What is the aetiology of Conn’s syndrome?
aetiology includes adrenal cortical hyperplasia, adenoma and familial hyperaldosteronism
What is addison’s disease?
primary adrenal cortical insufficiency caused by adrenal dysgenesis, adrenal destruction, autoimmune adrenalitis, tuberculosis
secondary is due to failure of ACTH secretion
What are the symptoms of Addison’s disease?
the autoimmune form is the most common
triad of hyperpigmentation, postural hypotension and hyponatraemia
What is the treatment for Addison’s disease?
treatment with long term steroid replacement
it has a high mortality is it is not diagnosed
What is an adrenal cortical nodule?
Who is more commonly affected?
a benign non-functional nodule of the adrenal cortex
it affects between 1.5 and 3% of the population
it is higher in elderly, hypotensive and diabetic patietns
What are the symptoms of adrenal cortical nodule?
What is the treatment?
there are no clinical symptoms and it is an incidental discovery on radiographic studies
no treatment is required
What is adrenal cortical adenoma?
What is the incidence like?
benign neoplastic proliferation of adrenal cortical tissue
symptoms are related to endocrine hyperfunction
incidence between 1-5% of the population
What are the symptoms of adrenal cortical adenoma?
aldosterone prodicing tumours cause Conn’s syndrome
cortisol-producing tumours cause Cushing’s syndrome
rare tumours cause virilisation
What is adrenal cortical carcinoma?
a malignant counterpart of the adrenal cortical adenoma
it accounts for 3% of endocrine neoplasms
What are the symptoms of adrenal cortical carcinoma?
What is the prognosis like?
symptoms are related to hormone excess
abdominal mass is present
prognosis is age and state dependent
5-year survival rate is about 70%
WHat is phaeochromocytoma?
What are the different types and causes?
catecholamine-secreting tumour arising from the adrenal medulla
10% are bilateral, 10% are extra-adrenal, 10% are malignant, 10% are familial and 10% are seen in children
most cases are sporadic but familial syndromes MEN2a and 2b, von Recklinghausen’s disease and vin Hippel-Lindau disease
What are the symptoms of phaeochromocytoma?
What is prognosis like?
symptoms of hypertension, palpitation, headaches and anxiety
elevated urine catecholamines, adrenaline and noradrenaline
excellent prognosis when benign and properly managed surgically
malignant tumour may pursue an aggressive course
