Week 7 - The Endocrine System Flashcards
What types of endocrine diseases can occur?
- underproduction
- overproduction
- mass lesions
What makes up the endocrine system?
Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Adrenal glands
How does the hypothalamus contribute to the endocrine system?
- located in the brain - above brain stem
- links the CNS to the endocrine system
- produces releasing and inhibiting hormones - stop and start the production of other hormones throughout the body
What hormones does the anterior pituitary gland produce?
- growth hormone
- thyroid stimulating hormone
- adrenocorticotrophic hormone
- follicle stimulating hormone
- lutenising hormone
- prolactin
What hormones does the posterior pituitary gland produce?
- ADH
- oxytocin
What pituitary diseases can occur?
Hyperpituitarism-related effects
-adenomas (benign tumours - functionally active)
Hypopituitarism-related effects
-injury, surgery, radiation, inflammation
Local mass effect
-compressing the optic chiasm
What is hyperpituitarism?
Condition due to the primary hypersecretion of pituitary hormones
What causes hyperpituitarism?
Most common:
-adenoma in anterior lobe
Other:
- cancer
- hyperplasia
What are the types of pituitary adenoma?
- functional - prolactinoma
- non-functional
- macroadenomas (>1cm in diameter)
- microadenomas (
What is the effect of having too much ACTH?
Cushing’s disease
-buffalo hump, moon face, poor wound healing, thin skin etc
What is the effect of having too much growth hormone?
- gigantism (children)
- acromegaly (adults)
What is the effect of having too much prolactin?
- galactorrhea/amenorrhea
- sexual dysfunction
- infertility
What is the effect of having too much TSH?
Hyperthyroidism
What is the effect of having too much FSH/LH?
- hypogonadism
- mass effects
- hypopituitarism (occurs with loss of 75% or more of the anterior pituitary parenchyma)
What are the causes of hypopituitarism?
- ischaemic necrosis of the pituitary: Sheehan’s syndrome (post-partum)
- non-functioning adenomas - grow to potentially cause hypopituitarism
- surgery or irradiation - take out too much
- inflammatory lesions - rare
What can be the causes of hyperthyroidism?
- Grave’s disease (autoimmune) - proptosis (bulging eyes, shouldn’t be able to see white at the bottom of the eye, muscle at the back of the eye cause them to bulge)
- over treatment by thyroxine (for hypothyroidism)
- infective - De Quervain’s thyroiditis - related to viral infection
- toxic multinodular goitre
- toxic adenoma - single nodule in the thyroid gland producing thyroxin
What are the symptoms of hypothyroidism?
- intolerance to heat
- fine, straight hair
- bulging eyes
- facial flushing
- enlarged thyroid
- tachycardia
- high systolic BP
- breast enlargement
- weight loss
- muscle wasting
- localised oedema
- menstrual changes (amenorrhea)
- diarrhoea
- tremors
- finger clubbing
Explain why Grave’s disease occurs
- auto-immune condition, stimulates auto-antibodies
- the auto-antibodies attach to TSH receptors, meaning the receptors are constantly stimulated
- however because the antibodies are blocking the TSH receptors, this means that TSH decreases but thyroxine increases (unregulated overproduction)
- negative feedback can’t occur so thyroid hormone production can’t be regulated
How is hyperthyroidism managed?
- testing: clinical and thyroid function tests (blood test)
- treat the cause
- carbimazole/propylthiouracil
- radioiodine therapy (ingest radioactive iodine, kills off thyroid gland - decreases production)
- thyroidectomy
What can cause a goitre and what precautions need to be made?
- iodine deficiency
- could be hyper/hypothyroidism
-ensure trachea is not compressed by it
What are the causes of hypothyroidism?
- iodine deficiency
- autoimmune - Hashimoto’s thyroiditis
- iatrogenic - surgery, radioiodine
- pituitary defects
- congenital
What are the symptoms of hypothyroidism?
-intolerance to cold
-receding hairline
-facial and eyelid oedema
-extreme fatigue
-thick tongue - slows speech
-anorexia
-brittle nails and hair
-hair loss
-apathy
-lethargy
-dry skin
-muscle aches/weakness
-constipation
Late clinical manifestations:
-weight gain
-Bradycardia
-subnormal temp
-thickened skin
-cardiac complications
-decreased LOC
What is Hashimoto’s thyroiditis and who does it effect?
Autoimmune destruction of the thyroid gland
- women > men
- 45-60 years old
How is hypothyroidism managed?
Thyroxine
How common is thyroid cancer and what is the most common type to get?
-relatively uncommon
- most common type is papillary carcinoma
- papillary thyroid carcinoma is a non-functional tumour
How many parathyroid glands are there what do they do and what are they regulated by?
4 in total (2 pairs - upper and lower)
- regulate calcium
- regulated by parathyroid hormone
What are the causes of hypoparathyroidism?
-removal by surgery (thyroidectomy)
- congenital
- hereditary (autoimmune)
What are the symptoms of hypoparathyroidism?
Due to low calcium:
- irritability
- tetany (condition marked by intermittent muscular spasms, caused by malfunction of the parathyroid glands)
- seizures
What can cause hyperparathyroidism?
Primary
-adenoma
Secondary
-chronic renal failure
Tertiary
-after renal transplant
What are the symptoms of hyperparathyroidism?
Due to hypercalcaemia:
- constipation
- depression
- seizures
- muscle wasting
- polyuria
- bone fractures
- kidney stones
What are the names parts of the adrenal glands?
Cortex
Medulla
How are hormones and what hormones are released from the adrenal glands?
- Trigger –> hypothalamus
- hypothalamus released corticotropin releasing hormone (CRH)
- pituitary gland then releases ACTH which acts on the adrenal glands which release:
Zona glomerulosa:
-mineralocorticoids (aldosterone -secreted by cortex)
Zona fasciculata:
-glucocorticoids (cortisol)
Zona reticularis
-sex hormones (testosterone, oestrogen)
What causes hyperaldosteronism?
Primary:
-Conn’s disease in >50% (excess production of the hormone aldosterone by the adrenal glands, resulting in low renin levels)
Secondary:
-due to high renin levels (renin - increases BP)
What are the symptoms of Conn’s disease?
- oedema
- hypertension
- high sodium
- low potassium
What is cortisol and what does it do?
Glucocorticoid
- essential to life
- regulates blood sugar
- inhibits inflammation
- stress response
- release by circadian rhythm (normal)
- stress
What can excess release of cortisol (glucocorticoid) cause?
Cushing’s syndrome
What causes Cushing’s syndrome?
- excess release of cortisol (glucocorticoid)
- ACTH releasing tumour (pituitary/lung)
- steroids
What are the symptoms of Cushing’s syndrome?
- emotional disturbance
- moon face
- osteoporosis
- cardiac hypertrophy - hypertension
- buffalo hump
- obesity
- thin, wrinkled skin
- abdominal striae
- amenorrhea
- muscle weakness
- purpura
- skin ulcers (poor wound healing)
What is Addison’s disease?
Adrenal insufficiency
What can cause Addison’s disease?
Autoimmune
Infection
Neoplasms
What are the symptoms of Addison’s disease?
- GI symptoms (anorexia, N&V, diarrhoea)
- weight loss
- hyperpigmentation
- low sodium, high potassium
What causes addisonian crisis?
Addisonian crisis = acute adrenal insufficiency
Caused by stopping steroids abruptly
Name the gonadocorticoids and where they are secreted from
Testosterone
Oestrogen
Both are secreted from the gonads
What are adrenaline and noradrenaline and where are they secreted from?
Adrenal medulla
Catecholamines
What is a phaeochromocytoma?
A rare, catecholamine-secreting tumour that may precipitate life-threatening hypertension
Malignant in 10% cases but may be cured by surgical removal
What are the symptoms/signs of phaeochromocytoma?
- hypertension
- sweating
- palpitations
- nervousness
- increased metabolic ratio
- rapid heart rate
What are multiple endocrine neoplasia (MEN)?
Group of inherited diseases resulting in proliferative lesions of multiple endocrine organs
Different types
What does the endocrine system secrete to cause an effect?
Hormones
