Endocrine 3 Flashcards
where are the adrenal glands located?
a pair of small, triangular-shaped glands located on top of each kidney.
What are the functions of the hormones released by the adrenal glands?
Control
- Blood pressure
- Metabolism
- Stress response: The adrenal glands produce hormones that help the body respond to stress, such as adrenaline and noradrenaline. This is known as the “fight-or-flight” response.
- Salt and water balance
- Sex characteristics
- Immune system
what are the 2 parts of the adrenal glands?
the adrenal cortex and the adrenal medulla.
The adrenal cortex is subdivided into what 3 parts?
- Zona glomerulosa
○ Produces mineralocorticoids (e.g. aldosterone) - Zona fasciculata
○ Produces glucocorticoids (e.g. cortisol) - Zona reticularis
Produces androgens
What does the adrenal medulla produce?
- adrenaline and noradrenaline
what produces aldosterone?
the zona glomerulosa of the adrenal cortex
what is the function of aldosterone?
Salt and water regulation
- stimulates sodium reabsorption in the distal convoluted tubule of the kidney in exchange for potassium and hydrogen
- increases water reabsorption due to sodium reabsorptiion
Helps to control blood pressure
what hormone helps regulate blood pressure by balancing sodium and potassium levels in the blood?
aldesterone
how is aldosterone regulated?
- low blood volume stimulates the release of angiotensin II
- angiotensin II stimulates the adrenal cortex the produce aldosterone
- aldosterone has a number of different actions including Na reabsorption, H20 reabsorption, K excretion
- aldosterone, therefore, causes a net increase in blood volume
- increased blood volume inhibits the production of angiotension II via negative feedback
What drugs can be used to inhibit aldosterone to reduce high blood pressure?
ACE inhibitors (angiotensin-converting enzyme inhibitors) - inhibit angiotensin II
AT2 blockers (angiotension II receptor blockers)
what primary hormone is responsible for controlling your bodys response to stress
cortisol
What converts angiotensin into angiotensin I?
+ what organ releases this?
Renin released from the the kidney converts angiotensin
What stimulates the kidneys to release renin?
A drop in blood pressure/drop in fluid volume
What organ releases ACE (angiotensin-converting enzyme) to convert angiotensin I to angiotensin II?
The lungs
What organ releases aldesterone?
The adrenal glands
What organ does aldesterone act on to stimulate the reabsorption of NaCl and H20 (salt and water)
The kidneys
When do we have higher levels of cortisol?
highest in the morning and lowest at night
Where is cortisol produced?
In the zona fasciculata of the adrenal cortex
What are the physiological steroid effects of cortisol?
- Antagonist to insulin, raises blood glucose levels by inhibiting glucose uptake in the tissues and stimulating glucose production. Stimulates gluconeogenesis
- lowers immune reactivity (reduces inflammation and immune response)
- raises BP
- inhibits bone formation
How is cortisol regulated in the body?
- CRH (corticotropin-releasing hormone) is secreted by the hypothalamus (influenced by stress, time of day, and serum cortisol levels)
- CRH travels in the blood and binds to receptors on the pituitary gland - this increases the production of adrenocorticotropic hormone (ACTH)
- ACTH released into the blood stream, travels to the adrenal gland, where it binds to a receptor on the adrenal cortex
- stimulates the release of cortisol into blood stream where it has wide ranging effects
- increasing cortisol inhibits production of CRH and ACTH
what is the purpose of steroid medication?
Enhanced glucocorticoid effect
- immunosuppression
- anti-inflammatory
enhanced mineralocorticoid effect
- salt and water retention
- hypertension
What is cushing’s syndrome?
a condition caused by having excess glucocorticoid (cortisol)
What are the different types of cushing’s syndome?
- ACTH driven cushing’s syndome - (e.g. ACTH-secreting pituitary adenoma or ectopic ACTH secretion)
- ACTH independent cushing’s syndrome (e.g. adrenal adenoma, adrenal carcinoma, iatrogenic cushing’s syndrome (this is a result of long term corticosteroid therapy)
- Pseudo-cushings syndrome
what is the difference between cushing’s disease and cushing’s syndrome?
Cushing’s disease is a specific type of cushing’s syndrome caused by a benign tumour in the pituitary gland that produces too much ACTH = excess cortisol
Whereas cushing syndrome is a set of symptoms caused by prolonged exposure to high levels of cortisol. This can be caused by a number of things.
What are the clinical features of Cushing’s syndrome?
- Central obesity (increased fat on chest and stomach but slim arms and legs
- “buffalo hump”, build up of fat on the back of your neck and shoulders
- Red puffy rounded face
- bruising
- stretch marks (striae)
- weakness in upper arms and thighs
- hypertension
- T2 diabetes
- decreased libido
- depression and mood swings
- osteopenia (bone fractures more easily)
- females - loss of periods
- males - erectile dysfunction
hirsutism (excess hair)
What investigations are used to diagnose Cushing’s syndrome?
- blood tests (cortisol, glucose, ACTH)
- urinary cortisol levels
- imagines (MRI checking for pituitary adenoma, CT checking for adrenal or actopic cause)
What are the treatment options for Cushing’s syndrome?
Transsphenoidal surgery (pituitary adenoma)
adrenalectomy
surgery for ectopic tumours
medication - metyrapone (blocks cortisol synthesis)
What are the primary causes of adrenal insufficiency? (loss of mineralocorticoid and glucocorticoid activity)
- Autoimmune = addison’s disease
- Infection = TB, HIV
- Vascular = Adrenal infarction/haemorrhage/embolism
- Tumour = metastases, lymphoma
- Sarcoidosis/amyloidosis
- Congenital
- Bilateral adrenalectomy
What is sarcoidosis?
a rare disease that causes inflamed tissue to form in body organs
What are the secondary causes of adrenal insufficiency (loss of glucocorticoids only)?
- hypothalamic pituitary dysfunction/destrcution - insufficient production of ACTH
What are the tertiary causes of adrenal insufficiency?
Iatrogenic causes are the most common
a common side effect for taking excessive glucocorticoids = chronic suppresion of ACTH leads to the adrenal glands becoming atrophied
What is addisons disease?
A rare long term endocrine disorder, characterised by the inadequate production of cortisol and aldosterone
What are the symptoms of Addison’s disease?
- muscle weakness
- abdominal pain
- dizziness
- anorexia
- loss of body hair
- increased thirst
- low mood
What are the signs of Addison’s disease?
- hypotension
- hyperkalaemia (increased K+)
- weight loss and lethargy
- hyperpigmentation (including oral mucosa)
- vitiligo
Why does pigmentation develop in addison’s disease?
Low cortisol levels will stimulate ACTH production by the pituitary gland
High ACTH levels will stimulate the production of melanocytes stimulating hormone (MSH) = excess melanin production = pigmentation
What investigations are used for adrenal insufficiency?
Blood tests
- hormone levels (cortisol, aldosterone, ACTH)
- Synacthen test (measures how well the adrenal gland produces cortisol)
- Renal Function
- glucose
Imaging
- CT scan
- MRI for pituitary gland visualisation
- CXR
What would be the suspected blood test findings for a patient with ACTH dependent Cushing’s syndrome (e.g. a pituitary adenoma)?
- High ACTH
- High cortisol
What would be the suspected blood test findings for a patient with ACTH independent Cushing’s syndrome (e.g. gland tumour)
- Low ACTH
- High cortisol
What condition are you suspecting with blood tests showing:
- Low ACTH
- High cortisol
ACTH independent Cushing’s syndrome (e.g. gland tumour)
What condition are you suspecting with blood tests showing:
- High ACTH
- High cortisol
ACTH dependent cushing’s syndrome
What condition are you suspecting with blood tests showing:
- High ACTH
- Low cortisol
- Synacthen Negative
Adrenal insufficiency - gland destrcution (Addison’s)
What condition are you suspecting with blood tests showing:
- Low ACTH
- Low cortisol
- Synacthen: Positive
Adrenal Insuffiency (pituitary failure)
What is Conn’s syndrome?
When the adrenal gland produces too much aldosterone production. Alesterone regulates blood pressure and Na and K levels, this excess of aldosterone causes the body to retain water and salt which increases fluid volume and increase blood pressure
What are the clinical features of Conn’s syndrome?
- Hypertension
- Polyuria
- Muscle weakness
What can trigger adrenal crisis?
- Infections, medical and dental treatment, stress, stopping or rapidly withdrawing from medications
What happens in an adrenal crisis
life-threatening emergency which occurs when the adrenal glands dont produce enough cortisol
How would an adrenal crisis present?
- Abdominal pain
- Dehydration
- Fever
- Confusion
- Hypotension
- Hypovolaemic shock
- Hypoglycaemia
- Vomiting and Diarrhoea
How would you manage an adrenal crisis in a dental practice?
- call 999
- lie patient flat and raise their legs
- administer O2
What are the dental implications of Cushing’s Syndrome?
- infection prevention
- delayed healing
- avoid pathological fractures during surgical treatment
What are the dental implications of adrenal insufficiency?
- conduct treatment in the morning
- control anxiety
- use long acting LA
- treat post operative pain
- prevent iatrogenic fractures during surgical treatment
