Endocrinology Flashcards
What group of diseases are characterised by dysfunction of hormone secreting glands?
Endocrine disease
What is meant by negative feedback regulation?
Where the increasing level of the control hormone causes a reduction in secretion of the active hormone
What is secondary failure of the endocrine system?
Control failure (e.g. where a master gland, such as the pituitary gland, stops working and cant regulate other glands)
What is primary failure in the endocrine system?
Dysfunction/failure originating in the peripheral endocrine gland itself
What is multiple endocrine neoplasia (MEN)?
Condition causing overgrowth or tumours on one or more endocrine glands
What is MEN 1?
A hereditary condition associated with tumours of the hormone producing endocrine glands (e.g. parathyroid, anterior pituitary, pancreatic islets)
Where are the most common associated tumours of MEN 1 found?
Adrenal cortex
What are commonly associated tumours of MEN 1?
Adrenal cortex, Carcinoid and lipoma
What is MEN 2a?
Condition characterised by medullary carcinoma of the thyroid, Phaeochromocytoma, parathyroid hyperplasia etc.
What is MEN 2b?
Rare inherited disorder characterised by medullary thyroid cancer, mucosal neuromas, Marfanoid appearance etc.
Where is the pituitary gland located?
In a small depression in the middle of the skull base, the sella turcica.
What are the two components of the pituitary gland?
Anterior and posterior
What controls the pituitary gland?
The hypothalamus
Which component of the pituitary gland only releasing hormones upon vascular control?
Anterior pituitary
Which component of the pituitary gland releases hormones upon vascular and neural control?
Posterior pituitary
How can growth of the pituitary gland affect vision?
Any growth of the pituitary gland will head upwards due to pressure of surrounding bone and cause trauma/ put pressure on the optic chiasma which will effect vision
Which two hormones is the posterior pituitary gland mostly concerned with?
- anti-diuretic hormone (ADH)
- oxytocin
Name the stimulating hormone, that is released from the anterior pituitary gland, which targets the thyroid gland.
TSH (thyroid stimulating hormone)
Name the stimulating hormone, that is released from the anterior pituitary gland, which targets the adrenal cortex.
ACTH (adrenocorticotrophic hormone)
Name the stimulating hormone, that is released from the anterior pituitary gland, which targets and affects the whole body.
GH (growth hormone)
Name the stimulating hormones, that are released from the anterior pituitary gland, which effect cyclical rhythms in the reproductive tissues.
- LH
- FSH
- Prolactin
What condition can develop from inadequate Anti-diuretic hormone (ADH) production?
Diabetes insipidus
What is the main characteristic of diabetes insipidus?
Passing lots of urine
What are the two main types of pituitary tumour?
- Functional adenoma
- Non-functional adenoma
What is a functional adenoma?
A tumour that produces an active hormone
What is a non-functional adenoma?
Tumour has no hormone secreting ability
How does a pituitary tumour lead to narrowing of an individuals visual field?
The tumour will grow and compress the optic chiasma, narrowing vision
What is trans-sphenoidal surgery?
A surgery performed through the nose and sphenoid sinus to remove pituitary tumours
What growth factor is often measured when looking at levels of growth hormone (GH)?
IGF-1
What is the function of IGF-1 in relation to growth hormone release?
It has a negative feedback on the pituitary gland to reduce growth hormone release
If a child has excess growth hormone, what condition will this result in?
Giantism
If an adult has excess growth hormone, what condition will this result in?
Acromegaly
What are the 6 dental signs of acromegaly?
- Change in occlusion
- spacing of teeth
- thickened lips
- Enlarged tongue
- “Shrunk dentures”
- Reverse overbite
What are the six general presenting features of acromegaly?
- Coarse features
- Enlarged supra-orbital ridges
- Broad nose
- Thickened lips
- Soft tissues
- Enlarged hands
What is carpal tunnel syndrome?
Where pressure on a nerve in your wrist causes pain and numbness in your hands and fingers
Why might an individual with acromegaly experience carpal tunnel syndrome?
Due to enlarged hand size
What other endocrine disorder is associated with acromegaly and why?
Type 2 diabetes mellitus, theres is insulin resistance from increased GH
Why might an individual with acromegaly develop cardiovascular disease?
Because the heart will have an increased role in dealing with increased body mass. The heart will also grow itself and become inefficient as a pump.
What is the term used to describe cardiac complications associated with acromegaly?
Acromegalic cardiomyopathy
What term is used to describe thyroid dysfunction in excess?
Hyperthyroidism
What term is used to describe thyroid deficiency?
Hypothyroidism
Are both hyperthyroidism and hypothyroidism usually primary or secondary in failure?
Primary (gland failure)
What is thyrotoxicosis?
“The clinical syndrome of excess circulating thyroid hormones “
What is another term for hypothyroidism?
Myxoedema
What are the four causes of hyperthyroidism?
- Graves’ disease
- Toxic multi-nodular goitre
- Toxic adenoma
- Pituitary tumour (rare)
What % of hyperthyroid cases are usually a cause of Graves’ disease?
70-80%
What is Graves’ disease?
An autoimmune disease that results in the overproduction of thyroid hormones, because auto-antibodies stimulate the TSH receptor to produce more hormones
What are the clinical signs of hyperthyroidism?
- warm moist skin
- tachycardia & atrial fibrillation
- increased blood pressure & heart failure
- tremor & hyperrefelxia
- eyelid retraction & lid lag
What are symptoms of hyperthyroidism?
- hot
- excess sweating
- weight loss
- diarrhoea
- palpitations
- Muscle weakness
- irritable
- manic
- anxious
What is a goitre?
Swelling of the thyroid gland (at the base of the neck)
What ophthalmology is associated with Graves’ disease?
- Proptosis (where eyeballs are pushed froward in socket)
- Peri-orbital oedema (swelling around eyes)
What is the most common cause of hypothyroidism, occurring in 90% of cases?
Autoimmune (Hashimoto’s) thyroiditis
What happens in Hashimoto’s disease?
Autoimmune thyroiditis is the most common cause. In this case, the antibody which is produced, attacks the thyroid gland itself and causes inflammation of the thyroid gland which causes gradual fibrosis and destruction of the specialised thyroid tissue
Along with Hashimoto’s disease, what are the other causes of primary hypothyroidism?
- idiopathic atrophy
- Radioiodine treatment/thyroidectomy surgery
- iodine deficiency
- drugs
- congenital
What drugs are antagonistic to the thyroid gland and will reduce thyroid hormone secretion, causing hypothyroidism?
- carbimazole
- amiodarone
- lithium
What are secondary causes of hypothyroidism?
-hypothalamic/pituiatry disease
What are the clinical signs of hypothyroidism?
- dry coarse skin
- bradycardia
- hyperlipadaemia
- psychiatric or confusion
- goitre
- delayed reflexes
What are the symptoms of hypothyroidism?
- tired
- cold intolerance
- weight gain
- constipation
- hoarse voice
- goitre
- puffed face
- angina
- ‘slow’ poor memory
- hair loss
What group of individuals is most commonly affected by hypothyroidism?
Middle aged and elderly Women
What are the presenting features of hashimotos thyroiditis?
- goitre
- hypothyroid features
When investigating thyroid disease, what three thyroid hormones can be measured through a blood test?
- T3, T4 and TSH
What imaging/ tissue investigations can be used to investigate thyroid disease?
- ultrasound scan (cysts)
- radioisotope scans (gland uptake)
- fine needle aspiration/biopsy
What will the levels of thyroid hormone be, in a case of hyperthyroidism with pituitary cause (rare)?
- raised TSH
- raised T3
What will the levels of thyroid hormone be, in a case of hyperthyroidism caused by Graves’ disease or adenoma? And why?
Low TSH
Raised T3
The pituitary gland recognises that there is too much hormone, tries to reduce gland stimulation by stopping production of TSH
What will the levels of thyroid hormones be, in a case of hypothyroidism with pituitary cause (rare)? And why?
Low TSH
Low T4
Pituitary gland is not seeking the thyroid gland to make thyroxine so the TSH and T4 are low
What will the levels of thyroid hormones be, in a case of hypothyroidism caused by gland failure? And why?
High TSH
Low T4
Thyroid gland cannot respond when it’s asked to make thyroid hormone by the pituitary, so the pituitary level of TSH is increased but still there is a low T4
What are the 4 treatment options for hyperthyroidism?
- carbimazole
- beta blockers (reduces side effects)
- Radioiodine
- surgery (partial thyroidectomy)
How does Radioiodine treat hyperthyroidism?
Radioiodine is taken up into the gland, the thyroid gland concentrates iodine to make the thyroid hormones and if this is radioactive, the iodine will decay with time, releasing particles which will damage and kill off cells reducing the bulk of thyroid tissues and bringing the patient back to a normal thyroid level.
What is the treatment option for hypothyroidism?
Thyroxine tablets (T4)
What feature would be indicative of thyroid cancer on a radioisotope scan?
“Cold” nodules
What are the two types of thyroid cancer?
- papillary
- follicular
Where are the adrenal glands located?
They sit on the kidneys
What is Addisons disease?
Where adrenal tissue is destroyed and no hormones can be produced
What disease is characterised by excess adrenal action?
Cushings disease
What class of hormones is produced in the adrenal cortex?
Corticosteroids
What are the three histological areas of the adrenal gland?
- Zona glomerulosa
- Zona fasicularis
- Zona reticularis
What hormone is produced in the Zona glomerulosa of the adrenal gland?
Aldesterone
What hormone is produced in the Zona fasicularis of the adrenal gland?
Cortisol
What hormone is produced in the Zona reticularis of the adrenal gland?
Adrenal androgens (male sex hormones)
What hormone does the hypothalamus release in adrenal regulation?
Cortico-trophic releasing hormone (CRH)
In adrenal regulation, What hormone is released from the anterior pituitary gland upon stimulation by CRH?
ACTH
In what location of the adrenal gland does ACTH target, and what hormone is secreted as a result?
Adrenal cortex & cortisol
What system controls aldesterone?
Renin-angiotensin system
What is the function of aldosterone?
Salt and water regulation
What two drug groups can inhibit the action of aldosterone?
- ACE inhibitors
- AT2 blockers
What are the main side effects of taking ACE inhibitors?
- cough
- angio-oedema
- oral lichenoid drug reactions
How do AT2 blockers inhibit action of aldosterone?
By blocking angiotensin receptor
How does cortisol raise blood pressure?
By enhancing salt and water reabsorption
How could high levels of cortisol lead to osteoperosis in the long term?
Because cortisol inhibits bone synthesis and in doing so reduces bone turnover
What are the 4 physiological steroid effects of cortisol?
- antagonist to insulin
- lowers the immune reactivity
- raises blood pressure
- inhibits bone synthesis