ENDOCRINE Flashcards
Name 3 complications of thyroid surgery
- damage to parathyroid glands can result in hypocalcaemia
- recurrent laryngeal nerve damage
- bleeding
What are the ECG findings in hypocalcaemia?
Prolonged QT
How does hypocalcaemia present?
Muscle cramps
Perioral tingling
When should a second drug be added in T2DM?
HbA1c >58 mol/mol
What is the most common cause of hyperthyroidism?
Graves disease
Give 4 causes of hyperthyroidism.
Graves
Toxic multinodular goitre (Plummer’s disease)
Solitary toxic thyroid nodule
Thyroiditis (De Quervain’s, Hashimoto’s, post-partum and drug-induced)
What is Plummer’s disease?
Toxic multinodular goitre
What is a solitary toxic thyroid nodule?
Single abnormal thyroid nodule releasing thyroid hormone
Benign adenomas
Treated by surgical removal
What is the difference between primary and secondary hyperthyroidism?
Primary - problem with the thyroid
Secondary - problem with hypothalamus/pituitary
What is the pathophysiology of Grave’s disease?
Autoimmune - TSH receptor antibodies
What are the risk factors for Grave’s disease?
Female
40-60 years
What is thyrotoxicosis?
Too much thyroid hormone
What is thyroid storm?
Rare medical emergency caused by too much thyroid hormone.
Which drugs can induce thyrotoxicosis?
Thyroxine
Amiodarone
What are the signs of hyperthyroidism?
• Sweating and heat intolerance • Tachycardia • Weight loss • Pretibial myxoedema • Brisk reflexes Exophthalmos
What are the symptoms of hyperthyroidism?
• Anxiety and irritability
• Fatigue
• Frequent loose stools
Sexual dysfunction
What features are unique to Graves disease?
Exophthalmos
Pretibial myxoedema
Thyroid acropachy
What are the features of thyroid storm?
Pyrexia
Tachycardia
Delirium
What features are unique to toxic multinodular goitre?
• Goitre with firm nodules
• Most patients are aged over 50
Second most common cause of thyrotoxicosis (after Grave’s)
What investigations should be done in thyrotoxicosis?
• ↓TSH, ↑T4/↑T3 • Abs: TSH receptor, TPO • ↑Ca, ↑LFTs • Isotope scan ↑ in Graves’ ↓ in thyroiditis Ophthalmopathy: acuity, fields, movements
What is an isotope scan?
Thyroid scans and uptake tests use small doses of radioactive chemicals to create pictures of the thyroid gland.
What is the management of hyperthyroidism?
Refer to endocrinology
1st line - carbimazole, normal thyroid function after 4-8 weeks then maintenance dose
2nd line - propylthiouracil
3rd line - radioactive iodine (destroys thyroid cells, hypothyroidism)
Why is carbimazole preferred to propylthiouracil?
Propylthiouracil is associated with severe hepatic reactions
What are the two approaches to long-term treatment for hyperthyroidism?
- Titration block (carbimazole titrated to normal levels)
2. Block and replace (carbimazole + levothyroxine)
What are the requirements for radioactive iodine treatment?
Not pregnant (must not be pregnant within 6 months) Avoid contact with anyone for 1 week Avoid children and pregnant women for 3 weeks
What is the management of thyrotoxic storm?
Admission
Fluid resuscitation
Beta-blockers
How are beta-blockers used in hyperthyroidism? What is first-line?
Control heart rate, reduce anxiety
Propranolol
What is the definitive management of hyperthyroidism?
Surgery
What are the complications of thyroid surgery?
Recurrent laryngeal nerve damage = hoarseness
Hypoparathyroidism
Hypothyroidism
How long is treatment needed for Grave’s disease?
12-18 months
50% relapse –> surgery, radioiodine
What is the most common cause of primary hyperaldosteronsim?
Bilateral idiopathic adrenal hyperplasia
What is Cushing’s syndrome?
What is Cushing’s disease?
Syndrome: signs and symptoms that develop after prolonged abnormal elevation of cortisol
Disease: pituitary adenoma (tumour) secretes excessive ACTH
Describe the adrenal axis
Hypothalamus –> CRH
Pituitary –> ACTH
Adrenals –> mineralocorticoids, glucocorticoids, androgens, catecholamines
What are the features of Cushing’s syndrome?
Round “moon” face Central Obesity Abdominal striae Buffalo Hump (fat pad on upper back) Proximal limb muscle wasting
What are the physiological effects of high levels of cortisol?
Hypertension Cardiac hypertrophy Hyperglycaemia (Type 2 Diabetes) Depression Insomnia
How does high-levels of cortisol affect bones and skin?
Osteoporosis
Easy bruising and poor skin healing
What are the causes of Cushing’s syndrome?
Exogenous steroids (in patients on long term high dose steroid medications)
Cushing’s Disease (a pituitary adenoma releasing excessive ACTH)
Adrenal Adenoma (a hormone secreting adrenal tumour)
Paraneoplastic Cushing’s (SCLC)
What is the most common cause of paraneoplastic Cushing’s?
SCLC - ectopic ACTH
What is the first-line investigation for Cushing’s syndrome?
Low dose dexamethasone test
Describe the dexamethasone test
Low dose - 1mg dexamethasone at 10pm, morning cortisol levels measured to screen for Cushing’s syndrome
If normal or high—> high dose dexamethasone test - 8mg dexamethasone to determine cause of Cushing’s syndrome
What is a normal result from a low dose dexamethasone test?
Low cortisol
What is also measured alongside a high dose dexamethasone test?
ACTH
What does a high dose dexamethasone test show in pituitary adenoma?
Cortisol - low
ACTH - low
What does the high dose dexamethasone test show in adrenal adenomas?
Cortisol - high/normal
ACTH - low
What does the high dose dexamethasone test show in paraneoplastic Cushing’s syndrome?
Cortisol - high
ACTH - high
What investigations should be done in Cushing’s syndrome?
- Dexamethasone suppression test (24-hour urinary cortisol can also be done but takes ages)
- FBC & U&E (low K)
- MRI brain (pituitary adenoma)
- Chest CT - SCLC
- Abdominal CT - adrenal tumours
What is the management of Cushing’s syndrome?
The main treatment is to remove the underlying cause (surgically remove the tumour)
- Trans-sphenoidal (through the nose) removal of pituitary adenoma (depends how big)
- Surgical removal of adrenal tumour
- Surgical removal of tumour producing ectopic ACTH
What are the 3 types of MEN?
MEN type I
MEN type IIa
MEN type IIb
What are the features of MEN type I?
3 Ps: (MEN1 gene)
Parathyroid (95%): hyperparathyroidism due to parathyroid hyperplasia
Pituitary (70%)
Pancreas (50%): e.g. insulinoma, gastrinoma (leading to recurrent peptic ulceration)
+adrenal, +thyroid
What are the features of MEN IIa?
Medullary thyroid cancer
2 Ps: (RET oncogene)
Parathyroid (60%)
Phaeochromocytoma
What are the features of MEN IIb?
(RET oncogene)
Medullary thyroid cancer
+ 1 P: Phaechromocytoma
What is included in a pituitary blood profile?
GH Prolactin ACTH FH LSH TFTs
What is the most common type of thyroid cancer?
Papillary - 70% (mostly young females, excellent prognosis)
What are the risk factors for type II diabetes?
Non-Modifiable
- Older age
- Ethnicity (Black, Chinese, South Asian)
- Family history
Modifiable
- Obesity
- Sedentary lifestyles
- High carbohydrate (particularly refined carbohydrate) diet
What are the symptoms of diabetes type II?
Fatigue Polydipsia and polyuria (thirsty and urinating a lot) Unintentional weight loss Opportunistic infections Slow healing Glucose in urine (on dipstick)
When is an oral glucose tolerance test done?
in the morning prior to having breakfast
baseline fasting plasma glucose result
giving a 75g glucose drink
measuring plasma glucose 2 hours later
What is pre-diabetes?
Pre-diabetes is an indication that the patient is heading towards diabetes.
They do not fit the full diabetic diagnostic criteria but should be educated regarding diabetes and implement lifestyle changes to reduce their risk of progressing to diabetes.
They are not currently recommended to start medical treatment at this point.
What is the difference between impaired fasting glucose and impaired glucose tolerance?
Impaired fasting glucose means that their body struggles to get their blood glucose levels in to normal range, even after a prolonged period without eating carbohydrates.
Impaired glucose tolerance means their body struggles to cope with processing a carbohydrate meal.
What is the diagnostic criteria for pre-diabetes?
HbA1c: 42-47 mmol/mol
Impaired fasting glucose: 6.1 – 6.9 mmol/l
Impaired glucose tolerance: glucose at 2 hours 7.8 – 11.1 mmol/l on an OGTT
What is the diagnostic criteria for type II diabetes?
HbA1c > 48 mmol/mol
Random Glucose > 11 mmol/l
Fasting Glucose > 7 mmol/l
OGTT 2 hour result > 11 mmol/l
How can you counsel a patient with type II diabetes?
Diet modification
Risk factors
Monitoring for complications
What dietary advice can be given to someone with type II diabetes?
Vegetables and oily fish
Typical advice is low glycaemic, high fibre diet
A low carbohydrate may in fact be more effective in treating and preventing diabetes but is not yet mainstream advice
How can you optimise risk factors in T2DM?
Exercise and weight loss
Stop smoking
Optimise treatment for other illnesses, for example hypertension, hyperlipidaemia and cardiovascular disease
Which complications should be monitored in T2DM?
Diabetic retinopathy
Kidney disease
Diabetic foot
What are the treatment targets for T2DM?
48 mmol/mol for new type 2 diabetics
53 mmol/mol for diabetics that have moved beyond metformin alone
What is the action of metformin?
ncreases insulin sensitivity and decreases liver production of glucose
“weight neutral”
What are the side effects of metformin?
Diarrhoea and abdominal pain (dose dependent)
Lactic acidosis
Does NOT typically cause hypoglycaemia
What are the side effects of pioglitazone?
Weight gain Fluid retention Anaemia Heart failure Extended use may increase the risk of bladder cancer Does NOT typically cause hypoglycaemia
What is the most common sylfonylurea?
gliclazide
What are the side effects of sulfonylureas?
Weight gain
Hypoglycaemia
Increased risk of cardiovascular disease and myocardial infarction when used as monotherapy
What are the diagnostic criteria for DKA?
Hyperglycaemia (i.e. blood glucose > 11 mmol/l)
Ketosis (i.e. blood ketones > 3 mmol/l)
Acidosis (i.e. pH < 7.3)
What is the management of DKA?
FIGPICK
F – Fluids – IV fluid resuscitation with normal saline (e.g. 1 litre stat, then 4 litres with added potassium over the next 12 hours)
I – Insulin – Add an insulin infusion (e.g. Actrapid at 0.1 Unit/kg/hour)
G – Glucose – Closely monitor blood glucose and add a dextrose infusion if below a certain level (e.g. 14 mmol/l)
P – Potassium – Closely monitor serum potassium (e.g. 4 hourly) and correct as required
I – Infection – Treat underlying triggers such as infection
C – Chart fluid balance
K – Ketones – Monitor blood ketones (or bicarbonate if ketone monitoring is unavailable)
How should you counsel a patient with a new diagnosis of T1DM?
- Life-long
- Glucose monitoring = morning, at each meal, before bed
- Insulin treatment = started by a specialist, long-acting, short-acting, lipodystrophy
- Short-term complications = hypoglycaemia, hyperglycaemia
- Long-term complications = macrovascular, microvascular, infection
- Monitoring = HbA1c
What are the macrovascular complications of T1DM?
Coronary artery disease is a major cause of death in diabetics
Peripheral ischaemia causes poor healing, ulcers and “diabetic foot”
Stroke
Hypertension
What are the microvascular complications of T1DM?
Peripheral neuropathy
Retinopathy
Kidney disease, particularly glomerulosclerosis
Which infections are common in patients with DM?
Urinary Tract Infections
Pneumonia
Skin and soft tissue infections, particularly in the feet
Fungal infections, particularly oral and vaginal candidiasis
How are C-peptide levels used in the diagnosis of diabetes?
When there is a lack of clarity between T1 and T2 e.g. older person presenting with features of T1 and having T2 risk factors e.g. obesity = test C-peptide
C-peptide = low in T1, normal in T2
What is subclinical hypothyroidism?
TSH raised but T3, T4 normal
no obvious symptoms
What is the management of subclinical hypothyroidism?
TSH is between 4 - 10mU/L and the free thyroxine level is within the normal range
- if < 65 years with symptoms suggestive of hypothyroidism, give a trial of levothyroxine. If there is no improvement in symptoms, stop levothyroxine
- ‘in older people (especially those aged over 80 years) follow a ‘watch and wait’ strategy, generally avoiding hormonal treatment’
- if asymptomatic people, observe and repeat thyroid function in 6 months
TSH is > 10mU/L and the free thyroxine level is within the normal range
- start treatment (even if asymptomatic) with levothyroxine if <= 70 years
- ‘in older people (especially those aged over 80 years) follow a ‘watch and wait’ strategy, generally avoiding hormonal treatment’
How should levothyroxine doses be changed in pregnancy?
Increase dose by 50%
Refer to endocrinologist
Which medications can reduce the absorption of levothyroxine?
Iron supplements
What is the screening test for acromegaly?
Serum IGF-1 (does not vary throughout the day)
Which tests can confirm the diagnosis of acromegaly?
oral glucose tolerance test (OGTT) with serial GH measurements
What is MODY?
Maturity-onset diabetes of the young (MODY) is characterised by the development of type 2 diabetes mellitus in patients < 25 years old
What is the optimum treatment for MODY?
Sulphonylureas
How do Phaeochromocytomas present?
triad of sweating, headaches, and palpitations in association with severe hypertension
What investigation is used to diagnose a phaeochromocytoma?
24 hr urinary collection of metanephrines (sensitivity 97%*)
What is the definitive management of a phaeochromocytoma?
Surgery is the definitive management. The patient must first however be stabilized with medical management:
alpha-blocker (e.g. phenoxybenzamine), given before a
beta-blocker (e.g. propranolol)
What does CRH stand for?
Corticotrophin releasing hormone
What does ACTH stand for?
Adrenocorticotropic hormone
What is the function of mineralocorticoids? Give an example of a primary and synthetic mineralocorticoid.
Control salt and water balance by promoting sodium and potassium transport.
Primary = Aldosterone Synthetic = Fludrocortisone
What is the function of glucocorticoids? Give an example of a primary and synthetic glucocorticoid.
Controls the production and use of sugar/fats and regulates the stress response.
Primary = Cortisol
Synthetic = Hydrocortisone, Prednisolone, Dexamethasone, Beclomethasone
What is the function of androgens?
Regulate the development of sex characteristics.
What is the function of catecholamines? Give an example
Fight or flight
Adrenaline (hormone)
Noradrenaline (neurotransmitter)
What is adrenal insufficiency?
Adrenal glands do not produce enough steroid hormones
Which two hormones in particular are lacking in adrenal insufficiency?
Cortisol
Aldosterone
What is Addison’s disease? What is another name?
Adrenal glands have been damaged
Primary adrenal insufficiency
What is the most common cause of primary adrenal insufficiency?
Autoimmune
What is Sheehan’s syndrome?
Blood loss during childbirth leads to pituitary gland necrosis
What is secondary adrenal insufficiency?
Inadequate production of ACTH
What is tertiary adrenal insufficiency?
Inadequate release of CRH from the hypothalamus - usually due to suddenly stopping long-term steroids
What is the presentation of adrenal insufficiency?
• Fatigue • Nausea • Cramps • Abdominal pain Reduced libido
What are the signs of adrenal insufficiency?
Bronze hyperpigmentation (ACTH stimulates melanocytes to produce melanin) Hypotension
What might be found on a U&E blood test in adrenal insufficiency?
Hyponatraemia
Hyperkalaemia
What test is diagnostic of adrenal insufficiency?
Short synacthen test
What other blood tests can be done?
ACTH
Adrenal autoantibodies - adrenal cortex antibodies & 21-hydroxylase antibodies
Describe how the short synacthen test works
Give synacthen (synthetic ACTH) in the morning Measure blood cortisol at baseline, 30mins and 60 mins after Cortisol should double, if not = primary adrenal insufficiency (Addison's)
Describe how the long synacthen test works
Give synacthen over a long period of time
If there is no cortisol response = primary adrenal failure
If there is some cortisol response = adrenal atrophy due to secondary adrenal insufficiency (pituitary problem)
Not really used anymore as can measure ACTH
What is the management of Addison’s?
Replacement steroids:
- Hydrocortisone (cortisol replacement)
- Fludrocortisone (aldosterone replacement)
What is an Addisonian crisis?
Acute presentation of severe Addison’s
The absence of steroids leads to a life threatening presentation
How do patients present with an Addisonian crisis?
• Reduced consciousness
• Hypotension
• Hypoglycaemia, hyponatraemia, hyperkaemia
Patients can be very unwell
What can cause Addisonian crisis?
First presentation
Infection
Trauma
Acute illness
What is the management of an Addisonian crisis?
• Intensive monitoring if unwell
• Parenteral steroids (i.e. IV hydrocortisone 100mg stat then 100mg every 6 hours)
• IV fluid resuscitation
• Correct hypoglycaemia
Careful monitoring of electrolytes and fluid balance
