Endocrine Flashcards
What is the difference between endocrine and exocrine secretion?
Endocrine = secrete directly into the bloodstream, without ducts Exocrine = secrete through ducts to a site of action
What are the 3 types of hormone action?
- Endocrine - blood-borne, acting at distant sites
- Paracrine - acting on nearby adjacent cells
- Autocrine - feedback on same cells that secreted that hormone
What 7 organs comprise the major endocrine system?
- Pituitary
- Thyroid
- Parathyroid
- Adrenal
- Pancreas
- Ovary
- Testes
Are water-soluble hormones stored in vesicles or synthesised on demand?
Water soluble hormones are stored in vesicles
How do water soluble hormones get into cells?
They bind to cell surface receptors
Give an example of a water soluble hormone
Peptides - TRH, LH, FSH
Monoamines
Are fat soluble hormones stored in vesicles or synthesised on demand?
Fat soluble hormones are synthesised on demand
How do fat soluble hormones get into cells?
They diffuse into the cell
Give an example of a fat soluble hormone
Steroids - cortisol, thyroid hormone
What are the differences between the half-life and clearance of water soluble and fat soluble hormones?
Water soluble = short half life and fast clearance
Fat soluble = long half life and slow clearance
Name 4 hormone classes
- Peptides
- Amines
- Iodothyrosines
- Cholesterol derivatives and steroids
Give 5 examples of a peptide hormones
- Insulin
- Growth hormone
- ADH
- CRH
- Somatostatin
Give an example of an amine hormone
Noradrenaline and adrenaline
Describe the pathway of adrenaline synthesis
Phenylalanine –> L-tyrosine –> L-dopa –> Noradrenaline –> Adrenaline
Name the enzyme that breaks down noradrenaline and adrenaline
Catechol-O-methyl transferase (COMT)
What are noradrenaline and adrenaline broken down into?
Normetadrenaline and metadrenaline
Name 3 sites of hormone receptor location
- Cell membrane
- Cytoplasm
- Nucleus
Where in the cell are peptide cell receptors located?
On the cell membrane
Where in the cell are steroid hormone receptors located?
In the cytoplasm
Where in the cell are thyroid/vitamin A and D cell receptors located?
In the nucleus
Give 5 ways in which hormone action is controlled
- Hormone metabolism
- Hormone receptor induction
- Hormone receptor down-regulation
- Synergism - combined effects of 2 hormones amplified (e.g. glucagon and adrenaline)
- Antagonism - one hormone opposes other hormone (e.g. glucagon and insulin)
What are the 2 types of feedback control?
- Negative feedback - response causes response loop to shut off
- Positive feedback - response causes more response to occur
What layer of the trilaminar disc is the anterior pituitary derived from?
Ectoderm (Rathke’s pouch)
What is the posterior pituitary derived from?
The floor of the ventricles
Name the 6 hormones that the anterior pituitary produces
- TSH - thyroid stimulating hormone
- FSH - follicle stimulating hormone
- LH - luteinising hormone
- ACTH - adrenocorticotrophic hormone
- Prolactin
- GH - growth hormone
Name the 2 hormones secreted form the posterior pituitary
- Oxytocin
2. ADH - antidiuretic hormone
Where are the posterior hormones synthesised?
In the hypothalamus
oxytocin = paraventricular nucleus
ADH = supraoptic nucleus
How are oxytocin and ADH transported form the hypothalamus to the posterior pituitary?
Transported down the icons of the hypothalamic hypophyseal tract
Give 2 functions of oxytocin
- Milk secretion
2. Uterine contraction
What is the function of ADH?
It acts on the collecting ducts of the nephron and increased insertion of aquaporin 2 channels –> water retention
Causes vasoconstriction
Give the 6 hypophysiotropic hormones released by the hypothalamus
- Thyrotropin-releasing hormone (TRH)
- Corticotrophin-releasing hormone (CRH)
- Gonadotrophin-releasing hormone (GRH)
- Growth hormone releasing hormone (GHRH)
- Somatostatin
- Dopamine
Describe the thyroid axis
Hypothalamus –> TRH –> Anterior pituitary –> TSH –> thyroid –> T3 and T4
T3 and T4 have a negative effect on the hypothalamus and the anterior pituitary
Which has a longer half life, triiodothyronine or thyroxine?
T3 has a half life of 1 day and T4 has a half life of 5-7 days
What would be the effect on TSH if you had an under active thyroid?
TSH would be raised as you have less T3/4 being produced so no negative feedback
What would a low TSH tell you about the action of the thyroid?
Indicates an over active thyroid
Lots of T3/4 being produced so more negative feedback on the pituitary and therefore less TSH
Give 4 functions of thyroid hormones (T3 and T4)
- Accelerates food metabolism
- Increases protein synthesis
- Stimulation of carbohydrate metabolism
- Enhances fat metabolism
- Increase in ventilation rate
- Increase in cardiac output and heart rate
- Brain development during foetal life and postnatal development
- Growth rate accelerated
Describe the mechanism of ACTH
Hypothalamus –> CRH –> Anterior pituitary –> ACTH –> adrenal cortex (zona fasciculata) –> glucocorticoid synthesis (cortisol)
Cortisol has a negative feedback on the hypothalamus and the anterior pituitary
Give 3 functions of cortisol in response to stress
- Mobilises energy sources - lipolysis, gluconeogenesis, protein break down
- Vasoconstriction
- Suppresses inflammatory and immune responses
- Inhibits non-essential functions - growth and reproduction
Describe the mechanism of LH and FSH
Hypothalamus –> GnRH –> anterior pituitary –> FSH/LH –> ovaries/testes
What cells does FSH act on?
Ovaries = Granulosa cells Testes = Sertoli cells
What cells LH act on?
Ovaries = theca cells Testes = Leydig cells
What is the function of granulosa cells?
Stimulated by FSH to convert androgens into oestrogen using aromatase
What is the function of theca cells?
Stimulated by LH to produce androgens that diffuse into granulosa cells to be converted into oestrogen
What is the function of Sertoli cells?
Produce Mullerian inhabiting factor (MIF) and inhibin and activins which acts on the pituitary gland to regulate FSH
Stimulates spermatogenesis
What is the function of leydig cells?
Stimulated by LH to produce testosterone
Describe the GH axis
Hypothalamus –> GHRH (+) or Somatostatin (-) –> anterior pituitary –> GH –> Liver –> IGF-1
What is the function of GH?
Stimulates growth and protein synthesis
What is the function of IGF-1
It induces cell division, cartilage and skeletal growth and protein synthesis
Briefly describe the mechanism of prolactin
Hypothalamus –> dopamine (-) –> anterior pituitary –> prolactin
What would happen to serum prolactin levels if something was to impact on the pituitary stalk and block dopamine release?
Prolactin levels would increase
Give 3 reasons that result in pituitary dysfunction
- Tumour mass effects
- Hormone excess
- Hormone deficiency
Define appetite
Desire to eat food
Define satiety
Feeling of fullness - disappearance of appetite after a meal
Define overweight/obesity
Abnormal or excessive fat accumulation that may impair health
Give 5 risks of obesity
- Life expectancy decreases by 10 years
- Type 2 diabetes
- Hypertension
- Coronary artery disease
- Stroke
- Osteoarthritis
- Obstructive sleep apnea
- Carcinoma
Where is leptin expressed and what is its effect on appetite?
Expressed in white fat Suppresses appetite (Anorexigenic)
Where is ghrelin expressed and what is its effect on appetite?
Expressed in the stomach Stimulates appetite (orexigenic)
Name 2 other hormones that decrease appetite
- Insulin
- PYY 3-36
- CKK
- Glucagon-like peptide (GLP)
Give 5 parathyroid hormone actions
- Increase Ca2+ reabsorption
- Decrease phosphate reabsorption
- Increase 1 alpha-hydroxylation of 25-OH vit D
- Increase bone remodelling (bone resorption >bone formation)
- Increase Ca2+ absorption because of increase 1,25(OH)2D (no direct effect)
When serum calcium levels are low, what are PTH levels?
PTH levels are high
When serum calcium levels are high, what are PTH levels?
PTH levels are low
What is the effect of hyperparathyroidism on serum calcium levels?
Hyperparathyroidism –> hypercalcaemia
Name 4 symptoms of hyperparathyroidism
Hyperparathyroidism = hypercalcaemia 1. Renal/biliary stones 2. Bone pain 3. Abdominal pain 4. Depression, anxiety, malaise Stones, Bones, Groans and Moans
Give 2 causes of primary hyperparathyroidism
Parathyroid adenoma
Hyperplasia
Increase PTH –> increase calcium –> decrease phosphate
Describe the pathophysiology of secondary hyperparathyroidism
Becomes hyperplastic to increase secretion of pTH to compensate chronic hypocalcaemia
Often due to CKD
How does tertiary hyperparathyroidism occur?
Prolonged uncorrected hypertrophy - glands become autonomous producing excess PTH
What blood results would you see in the 3 types of hyperparathyroidism?
Primary = hypercalcaemia Secondary = low serum calcium Tertiary = Raised calcium and PTH
Describe the treatment for hyperparathyroidism
Primary = surgical removal of adenoma Secondary = calcium correction and treatment of the underlying cause Tertiary = Calcium mimetic (cinacalcet) and possibly a total or subtotal parathyroidectomy
How does a calcium mimetic work?
Increases sensitivity of parathyroid cells to calcium so less PTH secretion occurs
What is the affect of hypoparathyroidism on serum calcium levels?
Hypoparathyroidism –> hypocalcaemia
Give 5 symptoms of hypoparathyroidism
Hypoparathyroidism = hypocalcaemia
- Spasm
- Paraesthesia around mouth and lips
- Convulsions
- Tetany
- Cramps
- Confusion
- Chvosteks sign - tap over facial nerve and look for spasm of facial nerves
- Trousseaus sign - inflate BP cuff 20 mmHg above systolic for 5 mins = hand spasm
- QT prolongation
Name 4 causes of hypoparathyroidism
- Transient
- Can follow anterior neck surgery
- Genetic - defects in PTH gene
- Autoimmune - DiGeorge syndrome
What are blood results for someone with hypoparathyroidism?
Calcium = Low PTH = Low Phosphate = High
What is the treatment for hypoparathyroidism?
Acute = IV calcium Persistant = Vitamin D analogue (alfacalcidol)
Give 3 causes of Hypercalcaemia
- Primary hyperparathyroidism
- Malignancy
- Vitamin D toxicity
- Myeloma
What is the treatment for hypercalcaemia?
Loop diuretic to return calcium to normal (furosemide)
Calcitonin
If Primary hyperparathyroidism = surgical removal
Give 2 ECG changes that you might see in someone with hypercalcaemia
- Tall T waves
2. Shortened QT interval
Name 3 causes of hypocalcaemia
- Increase serum phosphate due to CKD (most common) or phosphate therapy
- Reduced PTH function due to primary hypoparathyroidism, post thyroidectomy and parathyroidectomy
- Vitamin D deficiency due to reduced exposure of light
How would you diagnose hypocalcaemia?
Detailed history
eGFR to search for CKD
PTH levels
Vitamin D levels
How would you treat hypocalcaemia?
Acute = IV calcium
Persistent in vitamin D deficiency = vitamin D supplement
Persistent in hypoprarythroidism = alfacalcidol
Give 2 ECG changes that you might see in someone with hypocalcaemia
- Small T waves
2. Long QT interval
What does the parathyroid control?
Serum calcium levels
A low serum calcium triggers the release of PTH and a high serum calcium triggers c-cells to release calcitonin
What hormone does the parathyroid secrete and what is its function?
PTH - secreted in response to low serum calcium
What is released by c-cells in the parathyroid in response to high serum calcium?
Calcitonin
What biochemical test might you want to do to establish the cause of hypercalcaemia?
PTH measurement
What disease is described as being a ‘disorder of carbohydrate metabolism characterised by hyperglycaemia’?
Diabetes mellitus
What are the 4 cells that make up the islets of langerhans?
- Beta cells (70%)
- Alpha cells (20%)
- Delta cells (8%)
- Polypeptide secreting cells
What do beta cells produce?
Insulin
What to alpha cells produce?
Glucagon
What do delta cells produce?
Somatostatin
What is the importance of alpha and beta cells being located next to each other in the islets of langerhans?
Enables them to ‘crosstalk’
Describe the mechanism of insulin secreting from beta cells
- Glucose binds to beta cells
- Glucose metabolism occurs
- ADP –> ATP
- Causes K+ channels to close
- Membrane depolarisation occurs
- Calcium channels open allowing influx
- Insulin is released
Describe the insulin action at muscle and fat cells
- Insulin binds to membrane receptors
- Intracellular signalling cascade is stimulated
- GLUT-4 mobilisation to plasma membrane
- GLUT-4 integrates into plasma membrane
- Glucose enters cells via GLUT-4
Describe the physiological process that occur in the fasting state in response to low blood glucose
Low blood glucose = high glucagon and low insulin
- Glucogenolysis and gluconeogenesis
- Reduced peripheral glucose uptake
- Stimulates the release of gluconeogenic precursors
- Lipolysis and muscle breakdown
Describe the effect on insulin and glucagon secretion int he fasting state
Fasting state = low blood glucose
Raised glucagon and low insulin
How many precursors are needed for gluconeogensis?
3
Describe the physiological processes that occur after feeding in response to high blood glucose
High blood glucose = high insulin and low glucagon
- Glycogenolysis and gluconeogenesis are suppressed
- Glucose is taken up by peripheral muscle and fat cells
- Lipolysis and muscle breakdown suppressed
Describe the effect on insulin and glucagon secretion after feeding
Insulin is high, glucagon is low
Give 3 effects of insulin
- Suppresses hepatic glucose output - decrease glycogenolysis and gluconeogenesis
- Increases glucose uptake into insulin sensitive tissues
- Suppresses lipolysis and breakdown of muscle
Give 3 effects of glucagon
- Stimulates hepatic glucose output - increases glycogenolysis and gluconeogenesis
- Reduces peripheral glucose uptake
- Stimulates lipolysis and breakdown of muscle
Give 3 ways in which diabetes Mellitus can cause morbidity and mortality
- Acute hyperglycaemia which if untreated leads to acute metabolic emergencies, diabetic ketoacidosis (DKA) and hyperosmolar coma
- Chronic hyperglycaemia leading tissue complications - macrovasculaa and microvascular
- Side effects of treatment - hyperglycaemia
What type are gestational and medication induced diabetes refereed to?
Type 2 diabetes mellitus
Describe the natural history of T1DM
Genetic predisposition + trigger –> insulitis, beta cell injury –> pre-diabetes –> diabetes
T1DM is characterised by impaired insulin secretion. Describe the pathophysiological consequence of this
Severe inducing deficiency –> glycogenolysis/gluconeogensis/lipolysis all not suppressed and reduced peripheral glucose uptake –> hyperglycaemia and glycosuria
Perceived stress –> cortisol and adrenaline secretion –> catabolic state –> increased plasma ketones
Is T1DM characterised by a problem with insulin secretion, insulin resistance or both?
Characterised by impaired insulin secretion - severe insulin deficiency
Describe the pathophysiology of T1DM
Beta cells express HLA antigens
Autoimmune destruction –> beta cell loss –> impaired insulin secretion
At what are do people with T1DM present?
Usually present in childhood
Name 3 symptoms of DM
Thirst (fluid and electrolyte losses)
Polyuria (due to osmotic diuresis)
Weight loss
Describe the epidemiology of T1DM
Onset younger (<30 years) Usually lean More Northern European ancestry
A diagnosis of diabetes can be made by measuring plasma glucose levels. What would a persons fasting plasma glucose be if they were diabetic?
Fasting plasma glucose >7 mmol/L
A diagnosis of diabetes can be made by measuring plasma glucose levels. What would a persons random plasma glucose be if they were diabetic?
Random plasma glucose >11 mmol/L
What might someone’s HbA1c be if they have diabetes?
> 48 mmol/L
What happens to C-peptide in T1DM?
C-peptide reduces
How do you treat T1DM?
Education Glycaemic control through diet (low sugar, low fat, high starch) Insulin – twice daily and with meals Regular activity and healthy BMI BP and hyperlipidaemia control
Give 6 complications to Diabetes Mellitus
- Diabetic ketoacdiosis
- Diabetic nephropathy
- Diabetic retinopathy
- Diabetic neuropathy
- Hyperosmolar hyperglycaemic nonteotic coma
- Stroke, ischaemic heart disease, peripheral vascular disease
Give 2 potential consequences of T1DM
- Hyperglycaemia
2. Raised plasma ketones –> ketoacidosis
How is insulin administered in someone with T1DM?
Subcutaneous injections
Other than SC injections, how else can insulin be administered?
Insulin pump
Describe the different types of subcutaneous insulins that can be given to people with T1DM
- Ultra fast acting - Humalog - taken before eating in conjunction with a long acting insulin at night
- Long-acting insulin - insulin Glargine - taken before going to bed
- Pre-mixed insulin - NovoMix - taken twice daily
Give 4 potential complications of insulin therapy
- Hyperglycaemia
- Lipohypertrophy at injection site
- Insulin resistance
- Wight gain
- Interference with life style
What is the affect of cortisol on insulin and glucagon?
Inhibits insulin
Activates glucagon
Describe the pathophysiology of diabetic ketoacidosis
No insulin –> lipolysis –> FFA’s –> oxidised in the liver –> ketone bodies –> ketoacidosis
Name 3 ketone bodies
- Acetoacetate
- Acetone
- Beta hydroxybutyrate
Where does ketogenesis occur?
Liver
Give 5 signs of diabetic ketoacidosis
- Hypotension
- tachycardia
- Kassmaul’s respiration
- Breath smells of ketones
- Dehydration
Would you associate ketoacidosis with T1 or T2 DM?
Type 1
Give 3 microvascular compilation of DM
- Diabetic retinopathy
- Diabetic nephropathy
- Diabetic peripheral neuropathy
Give 2 macrovascular complications fo DM
CV disease
Stroke
What is the main risk factor for diabetic complications?
Poor glycemic control
What is the treatment for someone presenting with ketoacidosis?
- ABCDE
- IV normal saline
- IV soluble insulin via syringe driving and sliding scale
- Restore potassium levels
- Look for underlying cause
Give 3 endocrine diseases that can cause diabetes
- Cushing’s
- Acromegaly
- Phaeochromocytoma
What class of drugs can cause diabetes?
Steroids
Thiazies
Anti-psychotics
Is T2DM characterised by problem with insulin secretion, insulin resistance or both?
Characterised by impaired insulin secretion and insulin resistance
Describe the aetiology of T2DM
Genetic predisposition and environmental factors
Describe the pathophysiology of T2DM
Impaired insulin secretion and resistance –> impaired glucose tolerance –> T2DM –> hyperglycaemia and high FFAs
Why is insulin secretion impaired in T2DM
Due to lipid deposition in the pancreatic islets
Give 3 risk factors for insulin resistance in T2DM
- Obesity
- Physical inactivity
- Family history
What happens to insulin resistance, insulin secretion and glucose levels in T2DM?
Insulin resistance increase
Insulin secretion decreases
Fasting and post-prandial glucose increase
Why do you rarely see diabetic ketoacidosis in T2DM?
Insulin secretion is impaired but there are still low levels of plasma insulin
Low levels of insulin prevent muscle catabolism and ketogenesis
By how much has the beta cell mass reduced in T2DM when diagnosis usually occurs?
50% of normal beta cell mass
Describe the epidemiology of T2DM
Onset older (>30)
Usually overweight
More common in African/Asian populations
More common in general
Describe the treatment pathway for T2DM
- Lifestyle changes - lose weight, exercise, healthy diet and control of contributing conditions
- Metformin
- Metformin and sulfonylurea
- Metformin + sulfonylurea + insulin
- Increase insulin dose as required
How does metformin work in treating T2DM?
Increase insulin sensitivity and inhibits glucose production
How does sulfonylurea work in treating T2DM?
Stimulates insulin release
Give a potential consequence of taking Sulfonylurea for the treatment of T2DM
Hypoglycaemia
What is hypoglycaemia classified as?
Plasma glucose <3.9 mmol/L and if <3.0 mmol/L it is severe hypoglycaemia
Give 5 symptoms of hypoglycaemia
- Hunger
- Sweating
- Tachycardia
- Anxious
- Shaking
- Confusion
- Weakness
- Vision changes
Why does hypoglycaemia continuously get worse?
Glucagon is not produced so rely only on adrenaline and the threshold for adrenaline release gradually lowers after time
What are 5 risk factors of hypoglycaemia for those with T1DM?
- History of severe episodes
- HbA1c < 48 mmol/L
- long duration of diabetes
- Renal impairment
- Impaired awareness of hypoglycaemia
- Extremes of age
What are 5 risk factors of hypoglycaemia for those with T2DM?
- Advancing age
- Cognitive impairment
- Depression
- Aggressive treatment of glycaemia
- Impaired awareness of hypoglycaemia
- Duration of MDI insulin therapy
- Renal impairment and other co-morbidities
Give 3 impacts of non-severe hypoglycaemia
- Reduced quality of life
- Cause fear of hypoglycaemia
- Causes psychological morbidity
Give 6 consequences of hypoglycaemia
- Seizures
- Comas
- Cognitive dysfunction
- Fear
- Decrease in qualitative life
- Accidents
Briefly describe the treatment of hypoglycaemia
Recognise symptoms
Confirm the need for treatment (blood glucose <3.9 mmol/L)
Treat with 15g of fast-acting carbohydrate
Retest in 15 mins to ensure blood glucose >4.0 mmol/L and retreat if necessary
Eat a long acting carbohydrates to prevent recurrence
Why are patient with diabetes at a particular risk of hypoglycaemia?
In Diabetes there are defects in the physiological defences to hypoglycaemia and there is reduced awareness
What does prevention of hypoglycaemia include?
Eduction
Correct choice of therapy
Adjusting glucose targets in those at high risk
Specialist support from a MDT
Is insulin secretion or insulin resistance the driving force of hyperglycaemia in T2DM?
Hepatic insulin resistance is the driving force
Give a potential consequence of acute hyperglycaemia
Diabetic ketoacidosis and hyperosmolar coma
Give a potential consequence of chronic hyperglycaemia
Mirco/macrovascular tissue complications
A man presents with a history of weight loss, polyuria and nocturia. He is very unwell. The GP performs a capillary blood glucose which is found to be 17.2mmol/l. What is the most likely diagnosis of this mans symptoms?
Type 1 Diabetes Mellitus
Name 5 possible diseases of the pituitary
- Benign pituitary adenoma
- Craniopharygioma
- Trauma
- Apoplexy/Sheehans
- Sarcoid/TB
Give 3 potential consequences of a pituitary tumour
- Pressure on local structures - e.g. optic chasm = bilateral hemianopia
- Pressure on normal pituitary (lack of function) - Hypopituitarism
- Functioning tumours - e.g. Cushing’s, acromegaly, prolactinoma
Describe the growth hormone secretion from the anterior pituitary
It is secreted in a pulsatile fashion and increases during deep sleep
What is acromegaly?
Overgrowth of all organ systems due to excess growth hormone in adults
What is gigantism?
Excess GH production in children before fusion of the epiphyses of the long bones
Give 5 symptoms of acromegaly
- Change in appearance
- Increase in size of hands and feet
- Excessive sweating
- Headache
- Tiredness
- Weight gain
- Amenorrhoea
- Deep voice
- Arthralgia
Give 5 signs of acromegaly
- Prognathism - jaw protrusion
- Interdental separation
- Large tongue
- Spade like hands and feet
- Tight rings
- Bitemporal hemianopia
What can cause acromegaly?
A benign pituitary adenoma producing excess GH
Describe the epidemiology of acromegaly
1/200,000
Average age is 40 years
Mean duration of symptoms is 8 years
Reduces life expectancy by 10 years
What complications are associated with acromegaly?
- Arthritis
- Cerebrovascular events
- Hypertension and heart disease
- Sleep apnea
- T2DM
- Colorectal cancer
What investigation might you do on someone who you suspect has acromegaly?
- Plasma GH levels can exclude acromegaly
- Serum IGF-1 and GH = raised
- Oral glucose tolerance test
- MRI pituitary
What does the plasma GH level need to be to exclude acromegaly?
<0.4 ng/ml
What is the diagnostic test for acromegaly?
Oral glucose tolerance test - failure of glucose to suppress serum GH
What are the treatment options for acromegaly?
- Transsphenoidal surgical resection
- Radiotherapy
- Medical therapy
Give 3 potential complications of transsphenoidal surgical resection for the treatment of acromegaly
- Hypopituitarism
- Diabetes insidious
- Haemorrhage
- CNS injury
- Meningitis
What does the success of pituitary surgery depend on?
Size of the tumour and surgeon
What type of radiotherapy is usually used to treat acromegaly?
Stereotactic radiotherapy - highly specific so less radiation to surrounding tissues
What types of medical therapy can be used to treat acromegaly?
Dopamine agonists - Cabergoline
Somatosatin analogues - octreotide/ianreotide
GH receptor antagonists - pegvisomant
Give 3 advantages of using dopamine agonists in the treatment of acromegaly
- No hypopituitarism
- Oral administration
- Rapid onset
Give 2 disadvantages of dopamine agonists in the treatment of acromegaly using
- Can be ineffective
2. Risk of side effects
Name a dopamine agonist that can be used as a treatment for acromegaly
Cabergoline
Why can somatostatin analogues be used in the treatment of acromegaly?
They inhibit GH release
Why can GH receptor antagonists be used in the treatment of acromegaly?
They suppresses IGF-1
What is prolactinoma?
Lactotroph cell tumour of the pituitary
Prolactin secreting tumour
Name the 2 types of prolactinoma
- Microprolactinoma = most common, >90%
2. Macroprolactinoma = >10mm
Describe the epidemiology of prolactinoma
Incidence is 10/100,000
Prevalence is 90/100,000
Women > men
Give 3 causes of prolactinoma
- Pituitary adenoma
- Anti-dopaminergic drugs
- Head injury
Give 6 signs of prolactinoma
- Infertility
- Galactorrhoea
- Amenorrhoea
- Loss of libido
- Hypogonadism
- Visual field defects and headaches due to local effect of tumour
Briefly describe the pathophysiology of Prolactinoma
Increased release of prolactin can cause galactorrhoea and can inhibit FSH and LH
What test do you do to diagnose prolactinoma?
Measure serum prolactin
What is the treatment for prolactinoma?
Dopamine agonists - cabergoline, bromocriptine
- remarkable shirked with macro adenoma
Occasionally transsphenoidal pituitary resection
What is Cushing’s Syndrome?
Chronic, excessive and inappropriate elevated levels of circulating plasma glucocorticoids (cortisol)
What is Cushing’s Disease?
When Cushing’s syndrome is caused by a pituitary tumour so excess glucocorticoids due to inappropriate ACTY secretion
Give 8 signs/symptoms go Cushing’s disease
- Central obesity
- Moon face
- Hypertension
- Skin thinning and bruising
- Abdominal striae
- Mood changes - depression, lethargy, irritability
- Osteoporosis
- Muscle wasting
- Weight gain
- Gonadal dysfunction
- Immune dysfunction
- Acne
What can cause Cushing’s syndrome?
And are they ACTH dependent or independent?
- Adrenal tumour (adenoma or carcinoma) = ACTH independent
- Exogenous steroid (excess glucocorticoid administration) = ACTH independent
- Pituitary tumour (causes excess ACTH production) = ACTH dependent
- Ectopic ACTH syndrome (too much ACTH stimulating too much Cortisol) = ACTH dependent
What is a differential diagnosis of Cushing’s syndrome?
Pseudo-Cushing’s = excessive alcohol consumption can mimic the clinical and biochemical signs but resolved on alcohol recession
Describe the epidemiology of Cushing’s syndrome
10/1,000,000
Higher incidence in Diabetes
2/3 cases are Cushing’s disease
How can you diagnose Cushing’s syndrome?
- Overnight dexamethasone suppression test - failure to suppress cortisol
- Late night salivary cortisol - loss of circadian rhythm so cortisol is raised
- Urinary free cortisol = raised
- Loss of circadian rhythm
How does a dexamethasone suppression test work?
Give synthetic steroids that suppress pituitary and adrenals and then measure the cortisol
In Cushing’s there is no suppression of cortisol
What happens after a official diagnosis of Cushing’s syndrome has been made?
Figure out if it is ACTH dependent or independent
CT and MRI of adrenals and pituitary
What is the treatment for Cushing’s syndrome?
Tumours = surgical removal
Drugs to inhibit cortisol synthesis - metyrapone, ketoconazole
What are some complications associated with Cushing’s Syndrome?
Hypertension
Obesity
Death
What is the circadian system?
Body clock that regulates your body
Clear rhythm of cortisol production follows circadian rhythm
When do cortisol levels peak?
At around 8:30 am
What’s the primary cue that synchronises an organism’s biological rhythms?
Light
What is adrenal insufficiency?
Adrenocortical insufficiency resulting in a reduction of mineralocorticoids, glucocorticoids and androgens
Name the 3 types of adrenal insufficiency
- Primary - Addison’s disease (adrenal glands not working)
- Secondary - Hypopituitarism (lack of ACTH)
- Tertiary - Suppression of HPA due to presence of exogenous glucocorticoids
Give 5 primary causes of adrenal insufficiency
- Addison’s disease (autoimmune destruction of the adrenal cortex)
- Congenital adrenal hyperplasia (CAH)
- TB
- Adrenal metastases
- Drugs
- Haemorrhage
- Infection
Give 6 symptoms of adrenal insufficiency
- Tanned - pigmentations
- Fatigue
- Tearful
- Weight loss
- Headaches
- Abdominal cramps
- Myalgia
- Poor recovery from illness
- Adrenal crisis
What is the treatment for adrenal insufficiency?
Hormone replacement - any steroids - hydrocortisone
In Primary adrenal insufficiency (Addison’s disease) replace aldosterone with fludrocortisone
Give 3 secondary causes of adrenal insufficiency
- Hypopituitarism
- Withdrawal from long term steroids
- Infiltration
- Infection
- Radiotherapy
What biochemical investigations might you do in someone who you suspect has adrenal insufficiency?
0900 Cortisol and ACTH
Renin = elevated in primary
U+E (decrease sodium, increase potassium due to decrease aldosterone - increase in calcium and urea)
Synacthen test - > 450 nmol/L = AI unlikely
What results of cortisol and ACTH tests suggest adrenal insufficiency is likely?
Cortisol >500 nmol/L = AI unlikely
Cortisol <100 nmol/L = AI likely
ACTH > 22 ng/L = primary
ACTH < 5 ng/L = secondary
What investigations would you do to determine whether Adrenal insufficiency is primary or secondary?
Primary = adrenal antibodies, very long chain fatty acids, imaging and genetics Secondary = any steroids?, imaging and genetics
Adrenal crisis is a common presentation of adrenal insufficiency. Give 6 features of an adrenal crisis
- Hypotension
- Fatigue
- Fever
- Hypoglycaemia
- Hyponatreamia
- Hyperkalameia
What is the management of adrenal crisis?
Immediate Hydrocortisone 100mg
Fluid resuscitation - saline (IV)
Hydrocortisone 50-100 mg 6 hourly
In primary start fludocortisone
What would sodium and potassium levels be in someone with adrenal insufficiency?
Hyponatraemia = low sodium
Hyperkalaemia = high potassium
Lack of aldosterone and so less sodium reabsorbed and less potassium excreted
Give a sign of Cushing’s syndrome that is due to impairments in carbohydrate metabolism
Diabetes Mellitus
Give a sign of Cushing’s syndrome that is due to electrolyte disturbances
- Sodium retention
2. Hypertension
People with Cushing’s syndrome may have immune dysfunction. Give a consequence of this
Increased susceptibility to infection
Why is it important to take a drug history when speaking to someone with potential Cushing’s?
To exclude exogenous glucocorticoid exposure as a potential cause
When might you see signs of hypercortisolism without Cushing’s Disease?
- Pregnancy
- Depression
- Alcohol dependence
- Obesity
Briefly describe the mechanism of thyroid destruction
Cytotoxic (CD8+) T cell mediated
thyroglobulin and Thyroid peroxidase (TPO) antibodies may cause secondary damage (alone have no effect)
Antibodies against the TSH receptor may block the effect of TSH (uncommon)
What are the main 3 types of cells that cause thyroid destruction?
- Cytotoxic T cells
- Thyroglobulin
- TPO antibodies
Briefly describe the pathophysiology of Grave’s disease
Autoimmune disease
TSH receptor antibodies stimulate thyroid hormone production
Leads to hyperthyroidism
High circulating levels of thyroid hormone, with a low TSH
Give 5 Gravers opthlmopathy signs
- Exophthalmos eyes (bulging)
- Lid lag stare
- Redness
- Conjunctivitis
- Pre-orbital oedema
- Bilateral
- Extra ocular muscle swelling
Give 5 symptoms of Grave’s disease that don’t include opthalmopathy signs
- Weight loss
- Increased appetite
- Irritable
- Tremor
- Palpitations
- Goitre
- Diarrhoea
- Heat intolerance
- Malaise
- Vomiting
Give 5 signs of Grave’s disease that don’t include opthalmopathy signs
- Tachycardia
- Arrhythmias (e.g. AF)
- Warm peripheries
- Muscle spasm
- Pre-tibial myxoedema (raised purple lesions over the shins)
- Thyroid acropachy (clubbing and swollen fingers)