Endocrinology Flashcards
What is the difference between a endocrine and an exocrine gland?
- Endocrine = glands ‘pour’ secretions into the bloodstream
- Exocrine = glands ‘pour’ secretions through a duct to site of action
What are the endocrine glands?
- Hypothalamus
- Pineal Gland
- Pituitary Gland
- Thyroid
- Parathyroid
- Thymus
- Adrenal
- Pancreas
- Ovaries
- Testes
What are the three types of hormone action?
- Endocrine: the hormone is distributed in blood and binds to distant target cells
- Paracrine: the hormone acts locally on adjacent cells
- Autocrine: the hormone acts on the same cell that secreted it
Give an example of a water soluble hormone.
Peptides e.g. TRH, LH, FSH
Are water soluble hormones stored in vesicles or synthesised on demand?
Water soluble hormones e.g. peptides are stored in vesicles
How do water-soluble hormones e.g. peptides get into a cell?
They bind to cell surface receptors
Give an example of a fat soluble hormone.
Steroids, e.g. cortisol
Are fat-soluble hormones stored in vesicles or synthesised on demand?
Fat-soluble hormones, e.g. steroids are synthesised on demand
Where are the receptors found for:
a) peptide hormones
b) steroid hormones
c) thyroid hormone
a) cell membrane
b) cytoplasm
c) nuclear receptors
Give 5 ways in which hormone action is controlled.
- Hormone metabolism - increased metabolism to reduce function
- Hormone receptor induction
- Hormone receptor down-regulation
- Synergism - combined effects of two hormones amplified, e.g. glucagon and adrenaline
- Antagonism - one hormone opposes other hormone, e.g. glucagon antagonises insulin
Name two hormones that reduce appetite.
Leptin and PPY
Name a hormone that increases appetite.
Ghrelin (GREEDY)
Where is parathyroid hormone released from? What is it released in response to? What is its role?
- Parathyroid hormone (PTH) is released from the four parathyroid glands
- It is released in response to low calcium serum. It is also released in response to low magnesium and high phosphate serum
- Its role is to increase the serum calcium concentration
What does a high serum calcium concentration cause the release of and from where?
A high serum calcium concentration causes the release of calcitonin from the c-cells of the thyroid gland
What are the functions of PTH?
- Increases calcium reabsorption at the kidney (so less excreted in urine) and decreases phosphate reabsorption
- Stimulates the kidneys to convert vitamin D3 into calcitriol, which is the active form of vitamin D that promotes calcium absorption from food in the small intestine
- Increases bone resorption (increases number of osteoclasts in bone, causing reabsorption of calcium from the bone into the blood)
What is calcium used in?
Calcium is used in neurotransmission and muscle contraction
What are the causes of hypocalcaemia?
- Vitamin D deficiency (secondary hyperparathyroidism)
- Hypoparathyroidism
- Pseudohypoparathyroidism (PTH resistance)
- Hyperventilation
- Drugs
- Malignancy
- Toxic shock
What will the PTH, calcium and phosphate levels be like in vitamin D deficiency (secondary hyperparathyroidism)? Is this an appropriate or innapropriate response?
- PTH high
- Calcium low (Vitamin D causes calcium and phosphate reabsorption)
- Phosphate low
What will the PTH, calcium and phosphate levels be like in hypoparathyroidism? Is this an appropriate or innapropriate response?
- PTH low
- Calcium low (as less PTH to reabsorb it)
- Phosphate high (as less PTH to lower it)
- Innapropriate response as low PTH is the problem
What will the PTH, calcium and phosphate levels be like in pseudohypoparathyroidism (PTH resistance)?
- PTH high
- Calcium low
- Phosphate high
- Appropriate response because the PTH resistance is the problem
What are the symptoms and signs of hypocalcaemia?
- Symptoms: CATS go numb - convulsions, arrhythmias, tetany, spasm and numbness
- Signs: Chevostek’s (tapping facial nerve induces spasm) + Trousseau’s (BP cuff 20 mm Hg above systolic for 5 minutes causes wrist to flex and fingers to draw together)
What are the investigations for hypocalcaemia?
- Corrected calcium levels - done using serum calcium and serum albumin
- ECG (long QT interval)
- Parathyroid function
What is the management for hypocalcaemia?
- 10ml calcium gluconate/chloride 10% slow IV
- Oral calcium
- Vit D
What are the complications of hypocalcaemia?
Seizure, cardiac arrest (decreases heart rate and contractility) - a medical emergency!
What are the causes of hypercalcaemia?
- Malignancy (hypercalcaemia of malignancy)
- Primary hyperparathyroidism
- Sarcoidosis
- Thyrotoxicosis
- Drugs
What will the PTH and calcium levels be like in hypercalcaemia of malignancy? Is this an appropriate or inappropriate response?
- PTH low
- Calcium high (because this problem starts with a high Ca2+)
- Appropriate response
What will the PTH, calcium and phosphate levels be like in primary hyperparathyroidism? Is this an appropriate or innapropriate response?
- PTH high
- Calcium high
- Phosphate low
- Innapropriate response
What are the symptoms and signs of hypercalcaemia?
- Bones - bone pain
- Stones - kidney stones/renal calculi
- Groans - abdominal groans, e.g. abdominal pain, N+V, constipation
- Moans - psychic moans, e.g. depression/cognitive impairment
- Short QT interval
What are the investigations for hypercalcaemia?
- Corrected calcium levels
- ECG (short QT interval)
- Look for cause
What is the management for hypercalcaemia?
- Treat underlying cause
- Increase circulation volume, increase excretion
- Bisphosphonates, glucocorticoids, gallium, dialysis
What are the complications of hypercalcaemia?
Pancreatitis, confusion, coma, death
What is primary, secondary and tertiary hyperparathyroidism?
- Primary: 1 parathyroid gland produces excess PTH
- Secondary: increased secretion of PTH to compensate hypocalcaemia
- Tertiary: autonomous secretion of PTH even after correction of calcium deficiency, due to Chronic Kidney Disease (CKD)
What are the primary, secondary and tertiary causes of hyperparathyroidism?
- Primary: adenomas (80%), hyperplasia of all glands (20%)
- Secondary: low vit D/CKD (PTH increases Calcium through bone resorption, gut absorption, renal reabsorption and activating Vit D)
- Tertiary: develops from a prolonged secondary hyperparathyroidism
What is the epidemiology of hyperparathyroidism?
- Women
- 50-60 y/o
What are the symptoms and signs of hyperparathyroidism?
- Symptoms: bones, stones, groans and psychic moans:
- Osteoporosis
- Kidney stones (renal calculi)
- Constipation + acute pancreatitis
- Confusion
- Signs: hypercalcaemia, kidney stones
What are the investigations for hyperparathyroidism?
- PTH/bone profile - high PTH, high calcium, low phosphates:
- Primary: high calcium
- Secondary: high PTH, low calcium
- Tertiary: raised PTH, raised calcium
- DEXA, X ray (salt and pepper degradation of bone), ultrasound for stones
What is the management for hyperparathyroidism?
- Watchful waiting
- Primary = surgical removal of adenoma, give bisphosphonates
- Secondary = calcium correction, treat underlying cause
- Tertiary = Cinacalcet (calcium mimetic), total/partial parathyroidectomy
What are the complications of hyperparathyroidism?
- Hungry bone - rapid decrease in calcium/phosphate
- Pancreatitis, kidney stones causing damage, fractures
What are the causes of hypoparathyroidism?
Autoimmune, congential - acquired damage leads to low calcium
What is hypoparathyroidism? Describe primary and secondary hypoparathyroidism.
- Hypoparathyroidism = reduced PTH production
- Primary - gland failure. Autoimmune destruction, congenital - DiGeorge syndrome (22q11 del)
- Secondary - SURGICAL REMOVAL, decreased Mg (required for PTH secretion)
What are the risk factors for hypoparathyroidism?
Other autoimmune diseases
What are the symptoms and signs of hypoparathyroidism?
- Symptoms: Convulsions, arrythmias, tetany and numbness (CATs go numb)
- Signs: hypocalcaemia, Chevostek’s (facial nerve tap induces spasm), Trousseau’s (BP cuff causes wrist flexion and fingers to pull together)
What are the investigations for hypoparathyroidism?
- Bone profile - low PTH, low calcium, high phosphate
- ECG = prolonged QT + ST segments
What is the management for hypoparathyroidism?
- IV calcium
- AdCal-D3
- Synthetic PTH if required
What are the complications of hypoparathyroidism?
Cardiac arrest
What disease is described as being a ‘disorder of carbohydrate metabolism characterised by hyperglycaemia’?
Diabetes mellitus
What are the 4 cells to make up the Islets of Langerhans?
- Beta cells (70%)
- Alpha cells (20%)
- Delta cells (8%)
- Polypeptide secreting cells.
What do these cells produce:
a) alpha cells
b) beta cells
c) delta cells
d) polypeptide secreting cells
a) glucagon
b) INSULIN
c) somatostatin
d) pancreatic polypeptide
What is the importance of the alpha and beta cells being located next to each other in the Islets of Langerhans?
This enables them to ‘cross talk’ - insulin and glucagon show reciprocal action
Describe the mechanism of insulin secretion from beta cells.
- LEARN:
- Blood glucose levels rise. Glucose enters beta cells via GLUT-2 transporter
- Glycolysis begins to occur. This means that ATP is produced
- The rise in ATP causes the ATP-sensitive potassium channels to close, so K+ ions can no longer diffuse out of the cell, causing the membrane to depolarise
- The change in potential difference causes voltage-gated calcium channels to open, so Ca2+ ions diffuse into the beta cells down their concentration gradient
- Calcium ions cause vesicles containing insulin to move + fuse with the cell membrane, releasing insulin by exocytosis
What does a low blood glucose mean for glucagon and insulin levels? Describe the physiological processes that occur in the fasting state in response to low blood glucose.
Low blood glucose = high glucagon and low insulin.
- Glycogenolysis and gluconeogenesis.
- Reduced peripheral glucose uptake.
- Stimulates the release of gluconeogenic precursors.
- Lipolysis and muscle breakdown.
How many carbon precursors are needed for gluconeogenesis?
3
What does a high blood glucose mean for insulin and glucagon levels? 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.
A diagnosis of diabetes can be made by measuring plasma glucose levels. What would a person’s fasting plasma glucose be if they were diabetic?
Fasting plasma glucose >7mmol/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 >11mmol/l
A diagnosis of diabetes can be made by measuring plasma glucose levels. What would the results of the oral glucose tolerance test be if someone was diabetic?
Fasting plasma glucose >7mmol/l and 2-hour value >11mmol/l
What might someone’s HbA1c be if they have diabetes?
>48mmol/l
What is the effect of cortisol on insulin and glucagon?
Cortisol inhibits insulin and activates glucagon
What is the definition of type 1 diabetes mellitus? What is the epidemiology of the disease?
- Autoimmune destruction of pancreatic beta cells leading to complete insulin deficiency
- Epidemiology: 5-15 years (but can present at ANY age), 10% of DM
What are the risk factors for T1DM?
- Northern European
- Family history: HLA DR3-DQ2 or HLA-DR4-DQ8
- Other autoimmune diseases (90%), e.g. autoimmune thyroid, Coeliac disease, Addison’s disease, pernicious anaemia
What is the pathophysiology of T1DM?
- Autoantibodies attack beta cells in the Islets of Langerhans = insulin deficiency = hyperglycaemia
- Continued breakdown of liver glycogen (gluconeogenesis) = glycosuria
What are the symptoms and signs of T1DM?
- CLASSIC TRIAD: POLYDIPSIA, POLYURIA, WEIGHT LOSS (BMI < 25)
- Usually a short history of severe symptoms
- Typical patient with T1DM: polydipsia, polyuria, ketosis, rapid weight loss, young, BMI < 25, personal or family history of autoimmune disease
- Symptoms:
- Polydipsia
- Polyuria
- Unexplained weight loss (more common in T1)
- Hunger
- Nausea (more common in T1)
- Pruritis vulvae and balantis
- Signs:
- Breath smells of acetone
- Kussmaul breathing
Fill in the blanks: T_DM patients usually present with a ____ history of _____ symptoms.
T1DM patients usually present with a SHORT history of SEVERE symptoms (important)
When are we likely to make a diagnosis of T1DM?
- RANDOM PLASMA GLUCOSE of >11mmol/l
- Fits clinical picture: signs and symptoms, e.g. polydispsia, polyuria, weight loss, young, BMI < 25, personal and/or FHx of autoimmune disease
Why is polyuria a symptom of diabetes?
- Usually, when your kidneys create urine, they reabsorb all of the glucose and direct it back to the bloodstream
- In diabetes, excess glucose ends up in the urine, where it pulls more water, resulting in more urine
What is the treatment for T1DM?
- INSULIN (specifically basal-bolus insulin therapy, which involves taking slow-acting insulin to moderate blood glucose when fasting, and short-acting insulin around mealtimes to quickly reduce the impact of dietary glucose)
- Short-acting insulins and insulin analogues = 4-6 hours
- Longer-acting insulin = 12-24 hours
What are the different types of insulin?
- Rapid acting: insulin lispro, aspart or glulisine
- Short acting: regular insulin
- Intermediate acting: NPH
- Long acting: insulin glargine
- Insulin determir
Give 2 potential consequences of T1DM.
- Hyperglycaemia
- Diabetic ketoacidosis
What is diabetic ketoacidosis?
Complete lack of insulin results in high ketone production (cells can’t use glucose for energy, so they use fat for fuel instead. Burning fat makes acids called ketones). MEDICAL EMERGENCY
What is the aetiology of diabetic ketoacidosis?
- Untreated or undiagnosed T1DM
- Infection/illness
What is the pathophysiology of diabetic ketoacidosis?
- Complete absence of insulin = UNRESTRAINED increased hepatic gluconeogenesis and decreased peripheral glucose uptake = hyperglycaemia
- Peripheral lipolysis = increase FFA = oxidised to Acetyl CoA = ketones (acidic, cause anorexia and vomiting) = ACIDOSIS
- Hyperglycaemia (+ increased ketones) = more in urine = osmotic diuresis = dehydration
What are the symptoms and signs of diabetic ketoacidosis?
- Symptoms:
- Diabetes symptoms ++
- Polyuria and polydipsia
- Nausea and vomiting
- Weight loss
- Drowsy/confused
- Abdominal pain
- Signs:
- Kussmaul’s breathing
- Breath smells of ketones - ‘pear drop’
- Hypotension
- Tachycardia
- Dehydration
Which investigations would we perform for diabetic ketoacidosis? What would positive results look like?
- Hyperglycaemia: random plasma glucose >11mmol/l
- Ketonaemia: plasma ketones > 3mmol/l
- Acidosis: blood pH < 7.35 or bicarbonate <15mmol/l
- Urine dipstick: glycosuria/ketonuria
- Serum U+E: raised urea and creatinine, decreased total K+, increased serum K+
What are the complications of diabetic ketoacidosis?
- Coma
- Cerebral oedema
- Thromboembolism
- Aspiration Pneumonia
- DEATH
Why do you rarely see diabetic ketoacidosis in T2DM?
Insulin secretion is impaired but there are still low levels of plasma insulin. Even low levels of insulin can prevent muscle catabolism and ketogenesis
How do we manage diabetic ketoacidosis?
- ABC
- Replace fluid loss with 0.9% saline IV (ALWAYS COMES UP, THIS IS BEFORE INSULIN)
- IV insulin
- Restore electrolytes e.g. K+
FIG-PICK:
F - fluids; IV fluid resuscitation with normal saline
I - insulin; actrapid at 0.1 unit/kg/hr
G - glucose monitoring
P - potassium monitoring (should not be infused at >10mmol/hr)
I - infection; treat underlying triggers
C - chart fluid balance
K - ketone monitoring
What is the definition of type 2 diabetes mellitus?
A combination of peripheral insulin resistance and less severe insulin deficiency - patients gradually become insulin resistant/pancreatic beta cells fail to secrete enough insulin or BOTH
What are the risk factors for T2DM?
- Lifestyle factors: obesity, lack of exercise, calorie and alcohol excess
- Increase w/ age
- M > F
- Ethnicity: African-Caribbean, Black African and South Asian
- Obesity
- Hypertension
What would the clinical presentation of someone with T2DM be?
- Polydipsia and polyuria (more T2DM than T1DM)
- Glycosuria
- Central obesity
- Blurred vision
- SLOWER ONSET but similar symptoms to T1DM - but may present with complications
What are the normal levels for:
a) random glucose
b) fasting glucose
c) 2h post prandial glucose
d) HbA1c (mmol/mol)
e) HbA1c (%)
a) <11.1
b) <6.1
c) <7.8
d) <42
e) <6.0
What are the pre-diabetes levels for:
a) random glucose
b) fasting glucose
c) 2h post prandial glucose
d) HbA1c (mmol/mol)
e) HbA1c (%)
a) N/A
b) 6.1-6.9
c) 7.8-11.0
d) 42-47
e) 6.0-6.4
What are the diabetic levels for:
a) random glucose
b) fasting glucose
c) 2h post prandial glucose
d) HbA1c (mmol/mol)
e) HbA1c (%)
a) 11.1
b) 7.0
c) 11.1
d) >47
e) >6.4
What are the investigations for T2DM?
- Fasting plasma glucose: >7mmol/L
- Random plasma glucose: >11mmol/L
- HbA1c: >48mmol/L
What are the 5 steps for treating type 2 diabetes mellitus?
- FIRST LINE = lifestyle modification (diet, weight control, exercise, decrease alcohol intake, smoking cessation)
- 1st line therapy - METFORMIN (biguanide) = increases insulin sensitivity
- If HbA1c is still high, then DUAL THERAPY with metformin:
- DPP4 inhibitor
- Sulfonylureas - increase insulin secretion
- Pioglitazone
- SGLT-2i - If HbA1c is still high, try triple therapy
- Insulin
What is the mechanism of action and side effects for biguanides, e.g. metformin?
- Mechanism of action: decreased gluconeogenesis in liver and increase cell sensitivity to insulin
- Side effects: NOT hypoglycaemia, GI disturbances (anorexia, diarrhoea, vomiting)
What is the mechanism of action for sulfonylureas, e.g. glicazide?
- Mechanism of action: promote insulin secretion
- Side effects: hypoglycaemia, weight gain
What is a hyperosmolar hyperglycaemic state (HHS)? What is it a complication of?
- Marked hyperglycaemia
- Hyperosmolality
- MILD/NO KETOSIS
- Serious complication of T2DM
What is the pathophysiology of a hyperosmolar hyperglycaemic state?
- LOW INSULIN = increased gluconeogenesis = hyperglycaemia, but enough insulin to inhibit ketogenesis
- Hyperglycaemia -> osmotic diuresis -> dehydration
What are the characteristics of a hyperosmolar hyperglycaemic state?
- Caused by uncontrolled T2DM:
- Marked hyperglycaemia
- Hyperosmolality
- Mild/no ketosis
What is the clinical presentation of a hyperosmolar hyperglycaemic state?
- Extreme diabetes symptoms PLUS:
- Confusion and reduced mental state
- Lethargy
- Severe dehydration
How can we diagnose a hyperglycaemic hyperosmolar state?
- Random plasma glucose >11mmol/l
- Urine dipstick: heavy glycosuria
- Plasma osmolality: high
- U+E - decreased total body K+, increased serum K+
What is the treatment for a hyperglycaemic hyperosmolar state?
- Fluid replacement w/ 0.9% saline IV
- Insulin - at low rate of infusion!
- Restore electrolyte loss (K+)
- LMWH, e.g. SC enoxaparin to decrease risk of thromboembolism
Give 3 microvascular complications of diabetes mellitus.
- Diabetic retinopathy.
- Diabetic nephropathy.
- Diabetic peripheral neuropathy.
Give two macrovascular complications of diabetes mellitus.
CV disease and stroke
What is the commonest form of diabetic neuropathy?
Distal symmetrical polyneuropathy
Give 3 major clinical consequences of diabetic neuropathy.
- Pain
- Autonomic neuropathy
- Insensitivity
Describe the pain associated with diabetic neuropathy.
- Burning
- Paraesthesia
- Nocturnal exacerbation
Diabetic neuropathy clinical consequences: what is autonomic neuropathy?
Autonomic neuropathy - damage to the nerves that supply body structures that regulate functions such as BP, HR, bowel/bladder emptying
Diabetic neuropathy: give 6 signs of autonomic neuropathy.
- Hypotension
- HR affected
- Diarrhoea/constipation
- Incontinence
- Erectile dysfunction
- Dry skin
Give 6 risk factors for diabetic neuropathy.
- POOR GLYCAEMIC CONTROL
- Hypertension
- Smoking
- HbA1c
- Overweight
- Long duration of DM
What are the symptoms of hypoglycaemia?
- Trembling
- Palpitations
- Sweating
- Difficulty concentrating and speaking
- Confusion
- Drowsiness
- Vision changes
- Nausea
What are some causes of hypoglycaemia?
- Long duration of diabetes
- Tight glycaemic control with repeated episodes of non-severe hypoglycaemia
- Increasing age
- Use of drugs (prescribed, alcohol)
- Sleeping
- Increased physical activity
What is the alert value for hypoglycaemia? How do we treat hypoglycaemia?
- Alert value for hypoglycaemia: blood glucose = <3.9mmol/l
- Treat with 15g fast-acting carbohydrates
- Re-test in 15 minutes to ensure blood glucose >4.0mmol/l and re-treat if needed
- Eat a long-acting carbohydrate to prevent recurrence of symptoms
What sits above the pituitary gland? What does it do?
The hypothalamus sits above the pituitary gland and stimulates it with various hormones
What are the two parts of the pituitary gland? For either part, do they store or produce their hormones?
- Anterior pituitary - produces and releases its own hormones (under the regulation of hormones made by the hypothalamus)
- Posterior pituitary - stores and releases hormones produced by the hypothalamus
Which hormones are released by the anterior and posterior pituitary?
- Anterior pituitary = FLAGTOP:
- F: Follicle Stimulating Hormone (FSH)
- L: Luteinizing Hormone (LH)
- A: ACTH
- G: Growth Hormone (GH)
- T: Thyroid Stimulating Hormone (TSH)
- O: MSH – melanOcyte stimulating hormone
- P: Prolactin
- Posterior pituitary:
- ADH
- Oxytocin
Does the anterior pituitary have an arterial blood supply?
The anterior pituitary has no arterial blood supply but receives blood through a portal venous circulation from the hypothalamus
What 3 things can pituitary adenomas cause?
- Pressure on local structure e.g. optic nerves – Bitemporal hemianopia
- Pressure on normal pituitary – hypopituitarism
- Functioning tumour, e.g. prolactinoma, acromegaly, Cushing’s disease/syndrome
Describe the different groups of hormones secreted from the adrenal glands. State which part of the adrenal glands they are secreted from and give an example for each.
- MG’s got a GF called ARiana - Completely Caught Me!
- Mineralocorticoids - Zona Glomerulosa in cortex, e.g. aldosterone
- Glucocorticoids - Zona fasciculata of cortex, e.g. cortisol
- Androgens - Zona reticularis of cortex, e.g. sex hormones
- Catecholamines - Chromaffin cells in the adrenal medulla, e.g. adrenaline
Under normal circumstances, how is cortisol released?
- HPA axis
- Hypothalamus releases CRH (Corticotropin Releasing Hormone)
- This stimulates the anterior pituitary to release ACTH (Adrenocorticotropic hormone)
- Adrenal cortex releases cortisol
- Cortisol acts on liver, muscle, pancreas etc.
What is the aetiology of Cushing’s syndrome?
Chronic excess of cortisol released by the adrenal glands
What is the difference between Cushing’s disease and Cushing’s syndrome?
Cushing’s syndrome refers to the state of elevated cortisol levels. Cushing’s disease is specifically caused by an ACTH secreting pituitary tumour (pituitary adenoma)
What are the two types of causes of excess cortisol?
- ACTH dependent causes
- ACTH independent causes
What are the ACTH dependent causes of excess cortisol?
- Cushing’s disease: most common, caused by an ACTH secreting pituitary adenoma, leads to bilateral adrenal hyperplasia
- Ectopic ACTH production
- ACTH treatment
What are the ACTH independent causes of excess cortisol?
- Iatrogenic - steroid use (most common)
- Adrenal adenoma
What would the clinical presentation be of someone with Cushing’s syndrome?
- Central obesity
- Plethoric complexion
- Hirsutism
- Moon face
- Buffalo hump
- Mood change
- Proximal muscle weakness
- Purple abdominal striae
- Hypertension
- Acne
- Gastric ulcers
- Osteoporosis
What is the process of diagnosing Cushing’s syndrome?
- Drug history - Cushing’s can be caused by oral steroids, so exclude this first
- Random plasma cortisol (screening). IF HIGH…
- Overnight dexamethasone suppression test - cortisol will not be suppressed in Cushing’s disease (but normally they should decrease because dexamethasone should suppress ACTH levels)
- Urinary free cortisol (24 hr)
- Test plasma ACTH
Which investigation can be used to differentiate between the Cushing’s syndrome and Cushing’s disease?
Dexamethasone suppression test:
Overnight
- Cushing’s syndrome (including disease) is confirmed when there is no suppression
48 hour
- Cushing’s syndrome (not including disease) = no suppression
Is Cushing’s syndrome progressive? How do we treat Cushing’s syndrome?
- Cushing’s syndrome is progressive
- The treatment is dependent on the cause:
- Iatrogenic: stop medications if possible
- Pituitary adenoma = transsphenoidal surgical resection (1st line)
- Adrenal adenoma = adrenalectomy (1st line)
ALSO drugs to inhibit cortisol synthesis, e.g. metyrapone, ketoconazole
What are the complications of Cushing’s syndrome?
- Cardiovascular disease
- Hypertension
- Diabetes mellitus
- Osteoporosis
Describe the growth hormone axis.
- Growth hormone releasing hormone (GHRH) is released from the hypothalamus
- This stimulates growth hormone (GH) release from the anterior pituitary
- Growth hormone stimulates the release of insulin-like growth factor 1 (IGF-1) from the liver
What are the roles of growth hormone and IGF-1?
- Growth hormone stimulates bone and muscle growth, increases protein synthesis, stimulates the growth of internal organs
- IGF-1 drives growth too
What is acromegaly? What are the primary and secondary causes?
- Acromegaly = release of excess growth hormone causing overgrowth of all systems
- Causes:
- Primary: pituitary adenoma = most common (99%)
- Secondary to a malignancy that secretes ectopic GH, e.g. lung cancer
What are the symptoms and signs of acromegaly?
- Symptoms: large hands, box jaw, thick skin, arthritis, increased sweating, obstructive sleep apnoea, lower pitch of voice
- Signs: hypertension, insulin resistance, bitemporal hemianopia
What are the investigations required for acromegaly?
- 1st line = IGF-1 BLOOD TEST = raised
- Gold standard = ORAL GLUCOSE TOLERANCE TEST
- Other tests: random serum GH raised, MRI scan of pituitary fossa
How can we manage acromegaly?
- 1st line = Transsphenoidal pituitary surgery (if cause is adenoma)
- 2nd line = Somatostatin analogue, e.g. ocreotide - inhibits GH secretion
- 3rd line = GH receptor antagonist, e.g. pegvisomant
- 4th line = Dopamine agonist, e.g. cabergoline - bind to D2 receptor and suppress GH hypersecretion
What are the complications of acromegaly?
- Erectile dysfunction
- Diabetes
- Sleep apnoea
- Heart disease
What is the difference between acromegaly and gigantism?
Gigantism occurs if acquired before epiphyseal fusion. Often get people around 2.7m or 8ft11. Puberty often delayed
What is the epidemiology of prolactinoma?
- 2/10,000
- F > M
What is prolactinoma? What is a cause of hyperprolactinoma? What happens after?
- Prolactinoma = benign adenoma of pituitary gland producing excess prolactin
- Cause of hyperprolactinoma: non-functioning pituitary tumour - compresses pituitary stalk -> no inhibition of prolactin release
- This initiates lactation, breast development, controls osmolality + carbohydrate/fat metabolism
What is the pathophysiology of prolactinoma?
2 types:
- Micro (tumour less than 10mm diameter on MRI; most common (90%))
- Macro (tumour more than 10mm diameter on MRI)
- Increased release of prolactin can cause galactorrhoea by stimulating milk production from mammary gland, as well as inhibiting FSH and LH
What are the symptoms and signs of prolactinoma?
- Symptoms: amenorrhea, galactorrhoea, gynaecomastia, headache, visual field defect
- Signs: low testosterone/oestrogen, infertility
What are the investigations for prolactinoma?
- Prolactin levels
- CT head scan
What is the management for a prolactinoma?
- 1st line = DOPAMINE AGONISTS: bromocritipine/cabergoline (dopamine has an inhibitory effect on prolactin)
- Gold standard = TRANSSPHENOIDAL RESECTION SURGERY OF PITUITARY GLAND
What are the complications of prolactinoma?
- Infertility
- Sight loss
- Raised intercranial pressure
Define puberty.
Puberty describes the physiological, morphological and behavioural changes as the gonads switch from infantile to adult forms