Endocrinology Flashcards
Which HLA is usually present in T1 DM?
HLA DR4 +/- HLA DR3
What is the simple pathophysiology in T1 DM?
Insulin-producing ß cells of the islets of Langerhans in the pancreas are destroyed (auto-immune process)
What is the typical demographic for the onset of T1 DM?
Typically in a patient <25, lean body, acute
Why does polyuria and polydipsia occur in DM?
glucose spills into the urine and water follows, making glycosuria and dehydration
What are the three ways to diagnose diabetes?
- Symptoms + raised venous glucose (fasting ≥7, random ≥11.1)
- Raised venous glucose on 2 occasions (fasting ≥7, random ≥11.1)
- HbA1c ≥48 mmol/L (excluding pregnancy, children, haemoglobinopathy)
What are the SEs of S/C insulin?
SE: hypoglycaemia, weight gain, lipodystrophy
What lifestyle modifications can be given to a new T1 diabetic?
DAFNE course, smoking cessation, diet advice, test before driving
Baseline glucose monitoring is 4 times a day (before meals and bedtime). When should you monitor more frequently?
during illness, sport, planning preg
What is an example of a type of rapid-acting insulin, how long does it take to work and how long does its effects last?
NovoRapid
Takes 5 mins, lasts 3-5hrs
May be used as a bolus dose
What is an example of a type of short-acting insulin, how long does it take to work and how long does its effects last?
Actrapid
Takes 30 mins, lasts 6-8hrs
May be used as a bolus dose
What is an example of a type of intermediate-acting insulin, how long does it take to work and how long does its effects last?
Isophane insulin
Takes 2 hrs, lasts 12-18hrs
What is an example of a type of long-acting insulin, how long does it take to work and how long does its effects last?
Insulin determir/glargine – given 1-2 times/day
Takes 1-2hrs, lasts up to 24hrs
What is the simplified pathophysiology of T2 DM?
Relative deficiency of insulin d/t excess adipose tissue – there isn’t enough insulin to go around all the excess fatty tissue meaning blood glucose builds up
What does metformin do? What are its SEs and CIs?
increases insulin sensitivity + helps with weight, decreases hepatic gluconeogenesis
o SE: GI upset, lactic acidosis
o CI: stage 4 renal failure
What do Sulfonylureas (gliclazide) do? What are their SEs?
increases insulin secretions
o SE: weight gain, can cause hypoglycaemia, SIADH
If you have no pancreas function, won’t work
What do Thiazolidinediones (pioglitazone) do? What are their SEs and CIs?
increases insulin sensitivity
o SE: weight gain, fluid retention (worse in patients also on insulin), fractures
o CI: osteoporosis, CCF
What do DPP-4 inhibitors (-gliptins) do? What are their SEs?
increases incretin levels which inhibit glucagon secretion
o SE: increased risk of pancreatitis
o Good for patients who are obese
What do SGLT2 inhibitors (dapagliflozin) do? What are their SEs and CIs?
newer drug, prevents the resorption of glucose from the proximal renal tubules causing more glucose to be secreted in the urine
o SE: urinary/genital infections, weight loss, risk of Fournier’s Gangrene
o CI: recurrent thrush
What is the ‘simple measures’ sick day rules for diabetics?
- Increase frequency of blood glucose monitoring
- Encourage fluid intake (at least 3 litres in 24hrs)
- May need sugary drinks to maintain carb intake
- Patients should have box of ‘sick day supplies’
What should diabetics do about their medication on sick days?
• Continue medication even if not eating much (cortisol stress response increases blood sugar levels even without much oral intake)
o Except metformin which should be stopped if patient is becoming dehydrated – risk of renal damage
o Don’t stop insulin, risk of DKA
Patients should check ketone levels and give corrective insulin doses as required
Causes of lower than expected HbA1c?
- Sickle-cell anaemia
- GP6D deficiency
- Hereditary spherocytosis
Causes of higher than expected HbA1c?
- Vitamin B12/folic acid deficiency
- Iron-deficiency anaemia
- Splenectomy
In T2 DM, what HbA1c should you aim for and above what level would you consider adding in another agent?
Aim = <48mmol/L
Add Tx = >58mmol/L
Causes of raised prolactin?
The p’s
pregnancy
prolactinoma
physiological
polycystic ovarian syndrome
phenothiazines, metocloPramide, domPeridone
primary hypothyroidism (because TRH from hypothalamus stimulates prolactin release. In hypothyroidism there is a reactive increased in TRH, therefore prolactin)
What is secreted in the posterior pituitary?
ADH + oxytocin
What is secreted in the anterior pituitary?
GH, ACTH, FSH/LH, TSH, prolactin
Features of excess prolactin in men + women?
men: impotence, loss of libido, galactorrhoea
women: amenorrhoea, galactorrhoea
What occurs in Addison’s disease?
Autoimmune destruction of the adrenal glands -> primary hypoadrenalism
Responsible for 80% of cases
Other causes of primary hypoadrenalism?
TB
HIV
metastases (e.g. bronchial carcinoma)
meningococcal septicaemia (Waterhouse-Friderichsen syndrome - bleeding occurs into the glands (acute haemorrhagic necrosis)
antiphospholipid syndrome
Symptoms of Addison’s disease?
Bronze skin
Hypoglycaemia, WL, weakness, low mood
Postural hypotension
GI upset - N&V, abdo pain, diarrhoea/constipation
Investigations for Addison’s disease?
HIGH K+, LOW Na- (as a result of decreased aldosterone) Low glucose (as a result of decreased cortisol) Can do morning cortisol first: if \>500 - normal, \<100 - addison's, 100-500, do synacthen test Short ACTH stimulation test (synacthen test) -\> given synacthen (synthetic ACTH), cortisol levels should at least double, if not = addison's
Which antibodies are often positive in Addison’s disease?
21-hydroxylase adrenal auto-Abs
Treatment of Addison’s?
Replace steroids
- fludrocortisone + hydrocortisone
Give steroid card/bracelet
Causes of secondary hypoadrenalism?
Pituitary surgery
Infection
Sheehan’s syndrome
Causes of tertiary hypoadrenalism?
Iatrogenic d/t long-term steroid therapy
What should you do if someone with addison’s becomes sick?
Double to doses of both steroids
What occurs in an addisonian crisis?
Drop in steroid levels, may be due to:
1) First presentation of addison’s
2) Infection/trauma/acute illness
3) Sudden steroid withdrawal
How to treat an addisonian crisis?
IV hydrocortisone
IV fluids
Correct hypoglycaemia
Careful monitoring
Keep fludrocortisone the same - because high cortisone levels (from hydrocortisone) exert weak mineralocorticoid action
Can you take sulfonylureas when pregnant/breastfeeding?
No
What is the MOA of sulfonylureas?
Blockage of ATP-sensitive potassium channels
How common are each type of thyroid cancer?
Papillary (60%)
Follicular (25%)
Medullary (5%)
Anaplastic (1%) - present with compression symptoms e.g. stridor
Lymphoma
Who usually gets papillary thyroid Ca, what do you see on biopsy and how does it spread?
Younger patients (female)
Spreads to LNs
Light microscopy - orphan annie eyes
Who usually gets follicular thyroid Ca and how does it spread?
Women >50
Haematogenous -> bone, lungs
What tumour markers can be used for thyroid cancers?
Thyroglobulin - papillary + follicular
Calcitonin - medullary
Symptoms of thyroid cancer?
Painless, hard, immobile nodule
May be hoarseness/trouble swallowing with invasion of surrounding structures
What is sick euthyroid syndrome?
Occurs in systemic illness
Changes are reversible, no treatment needed
TSH (low or normal), T3/T4 (low)
What is subacute (De Quervain’s) thyroiditis?
Occurs following viral infection
Painful goitre
Typically in patients with hyperthyroidism
Usually self-limiting
Get an initial surge in thyroxine, then a drop
Tx = NSAIDS
What are the 3 defining features of Hashimoto’s thyroiditis?
Hypothyroidism
Goitre
Anti-thyroid peroxidase Ab (+ anti-thyroglobulin (Tg) Abs)
What are the levels of the adrenal gland and what do they produce?
Zona glomerulosa -> mineralocorticoids (aldosterone)
Zona fasciculata -> glucocorticoids (cortisol)
Zona reticularis -> androgens
Medulla -> NAd, Ad
What are the three causes of cushings syndrome?
Cushings disease (70%) - pituitary adenoma, causes bilateral adrenal hyperplasia
Ectopic ACTH secretion (10%) - especially from lung SCLC + carcinoid
Primary adrenal disease - from a Ca/nodular hyperplasia
Symptoms of cushings syndrome?
Buffalo hump
Round face
Thin skin, easy bruising
Abdominal striae
Osteoporosis
Muscle weakness
HTN
DM
What investigation for cushings?
Firstly, collect 24hr urine free cortisol OR do overnight dexamethasone suppression test (low-dose) and measure serum cortisol in the morning
Dexamethasone suppression test
Low-dose test:
Low cortisol -> normal
High/normal cortisol -> confirms cushings syndrome
High-dose test:
Low cortisol -> cushings disease
High/normal - measure ACTH
ACTH raised -> ectopic ACTH production
ACTH low -> adrenal cushings
Treatment of cushings syndrome?
Cushings disease:
- trans-sphenoidal tumour resection
- may choose bilateral adrenelectomy
- metyrapone/ketoconazole may lower serum cortisol pre-op
Adrenal tumour: unilateral adrenalectomy
Ectopic secretion: surgical resection
What is inferior petrosal sinus sampling and when is it used
Invasive procedure in which ACTH levels are sampled from the veins that drain the pituitary gland
Then compared with the ACTH levels in the peripheral blood to determine whether a pituitary tumor is responsible for ACTH-dependent Cushing syndrome (or if there is an ectopic source)
What tests to do if someones fasting glucose is between 6.1-7.0?
Should then be offered an oral glucose tolerance test to rule out a diagnosis of diabetes
A result between 7.8 - 11.1 mmol/l indicates that the person doesn’t have diabetes but does have IGT
What causes acromegaly?
Pituitary tumour (99%) Hyperplasia
Symptoms of acromegaly?
SOL -> headaches, bitemporal hemianopia
Prominent forehead (frontal bossing)
Large nose, hands, feet
Large tongue + protruding jaw
Organ dysfunction -> cardiomegaly, HTN, T2DM, CC
Carpel tunnel syndrome
Investigations in acromegaly?
First-line: Serum IGF-1 levels
If IGF-1 raised, do:
OGTT - measure every half hour for 2.5hrs
- glucose usually suppresses GH, not in acromegaly
Also do serial GH measures
MRI
Old photos
Management of acromegaly?
1) Trans-sphenoidal surgery
2) Somatostatin analogues - octreotide
3) Dopamine agonists - cabergoline, bromocriptine
4) GH receptor antagonists - pegvisomant
What does GH metabolise into in the liver?
Insulin-like growth factor 1 (IGF-1)
What are the two histological types of cervical cancer?
squamous cell cancer (80%)
adenocarcinoma (20%)
RFs for cervical cancer?
HPV 16, 18, 33
Smoking
High parity
Early first intercourse/many sexual partners
cOCP
Symptoms of hyperthyroidism?
Diarrhoea
Weight loss/muscle wasting
Increased appetite
Overactive/tremor
Oedema
Sweating/intolerance to heat
Proptosis
Goitre
Tachycardia/HTN
Three characteristic symptoms in Graves?
1) Eye disease
2) Pretibial myxoedema (orange peel skin)
3) Thyroid acropathy (clubbing/swelling)
Cause + RF for thyroid eye disease and Tx if severe?
Swelling in extra ocular muscles most likely d/t autoantigen in muscles that reactive with thyroid autoantigen
RF = Smoking
IV methylprednisolone/surgical decompression
Treatment of hyperthyroidism?
1) B-blockers
2) Anti-thyroid medications - carbimazole (inhibit production of thyroid hormones by blocks thyroid peroxidase)/propylthiouracil (inhibits T4->T3)
3) Radioiodine (damaged DNA/enzympes)
4) Thyroidectomy
Other than Graves what can cause hyperthyroidism?
Toxic multinodular goitre - nodules in goitre produce thyroxine irrespective of TSH levels
Toxic adenoma (solitary goitre)
Drug-Induced - amiodarone, iodine
Pathophysiology of Graves disease?
Circulating thyroid stimulating IgG antibodies cause activation of G-protein coupled thyrotropin receptors
What can happen to the foetus and mother if a mother has untreated thyrotoxicosis?
fetal loss, maternal heart failure and premature labour
What will happen to the levels of TBG/free T3 + T4 in pregnancy?
Thyroid binding globulin (TBG) levels rise during pregnancy in response to elevated estrogen levels. Because the majority of T4 and T3 circulates bound to TBG the total T4 and total T3 measurements will also rise, but the levels of free T4 and free T3 will not be affected.
Which drugs should be used to treat hyperthyroidism in pregnancy?
Propylthiouracil i-> first trimester of pregnancy
Carbimazole -> beginning of the second trimester
(Carbimazole in 1st trim may be associated with an increased risk of congenital abnormalities)
What should the target thyroxine levels be for pregnant women?
maternal free thyroxine levels should be kept in the upper third of the normal reference range to avoid fetal hypothyroidism
Women may therefore require an extra doses of thyroxine during pregnancy (by up to 50% as early as 4-6 weeks of pregnancy)
When should you measure TSH in pregnancy?
serum TSH measured in each trimester and 6-8 weeks post-partum
What is the male:female ratio in Hashimoto’s?
M:F 1:10
Which cancer is Hashimoto’s associated with?
MALT lymphoma
Biopsy: extranodal marginal B-cells
What is the inheritance pattern for MEN?
AD
What occurs in MEN type 1?
Parathyroid (95%): hyperparathyroidism due to parathyroid hyperplasia Pituitary adenoma (70%) Pancreatic tumours (50%): e.g. insulinoma, gastrinoma (leading to recurrent peptic ulceration)
Common symptoms: peptic ulceration, galactorrhoea, hypercalcaemia
What occurs in MEN type 2a?
Parathyroid hyperplasia (60%) Phaeochromocytoma
Medullary thyroid carcinoma
What occurs in MEN type 2b?
Phaeochromocytoma
Marfanoid body habitus
Mucosal neuromas
Medullary thyroid carcinoma
Which genes are responsible for MEN 1/2a/2b?
1 = MEN1 gene 2a/b = RET oncogene
Most common presentation of MEN1?
Hypercalcaemia
What is von-hippel lindau syndrome?
Von Hippel-Lindau syndrome is an inherited disorder characterized by the formation of tumors and fluid-filled sacs (cysts) in many different parts of the body
Affecting the CNS, kidneys, pancreas, adrenal glands, liver and lung. The most common presenting features are haemangioblastomas are seen in the brain, spinal cord and retina causing headaches, neurological disturbance and visual changes
What is a phaeochromocytoma?
A rare catecholamine secreting tumour that grows from chromaffin cells in the adrenals
Rule of 10%s in phaeochromocytomas?
10% familial
10% bilateral
10% malignant
10% extra-adrenal
Symptoms of phaeochromocytomas?
Episodic features of:
HTN
headaches
palpitations
sweating
anxiety
(symptoms of increased adrenaline)
Investigations for phaeochromocytomas?
24hr urinary collection of metanephrines
Management of phaeochromocytomas?
First stabilise with medical treatment:
- alpha-blockers (phenoxybenzamine)
- then beta-blockers (propranolol)
Then surgical intervention
Why do you give alpha-blockers before beta-blockers in the treatment of phaeochromocytomas?
Because B-blockers prevent the vasodilatory effects of peripheral B-2 adrenoceptors, potentially leading to unopposed alpha-adrenoreceptor stimulation causing vasoconstriction and ultimately a hypertensive crisis
What is a dynamic pituitary function test?
Used to assess for suspected primary pituitary dysfunction
Insulin, TRH and GnRH are given to the patient following which the serum glucose, cortisol, growth hormone, TSH, LH and FSH levels are recorded at regular intervals
In an OD of anti-glycaemic medications, which molecule is produced first?
the first response of the body is to decrease the production of insulin and then to increase glucagon secretion. Glucagon promotes gluconeogenesis in an attempt to raise blood glucose levels.
GH and cortisol are also released but later.
sympathoadrenal response: increased catecholamine-mediated (adrenergic) and acetylcholine-mediated (cholinergic) neurotransmission in the PNS and in the CNS
What is galactosaemia?
Raised galactose in the blood
What are the symptoms of galactosaemia?
Liver, eyes, kidney, brain
Brain damage, cataracts, jaundice, hepatomegaly, kidney damage
What causes galactosaemia?
The absence of galactose-1-phosphate uridyl transferase
In alcoholics with hypoglycaemia, what do you need to remember to give at the same time as glucose?
In alcoholic patients, thiamine supplementation should be given with, or following, the administration of intravenous glucose to minimise the risk of Wernicke’s encephalopathy
Which type of glucose preparation should be given to alcoholics with hypoglycaemia?
IV glucose
They have depleted glycogen stores, therefore, treatment with glucagon does not improve blood glucose
(because IM glucagon works by breaking down glycogen into glucose)
Causes of hypoglycaemia?
insulinoma - increased ratio of proinsulin to insulin
self-administration of insulin/sulphonylureas
liver failure
Addison’s disease
alcohol
nesidioblastosis - beta cell hyperplasia
What are the symptoms of hypogylcaemia?
BM <3.3 mmol/L cause autonomic symptoms d/t the release of glucagon and adrenaline:
Sweating, shaking, hunger, anxiety, nausea
BM <2.8 mmol/L cause neuroglycopenic symptoms due to inadequate glucose supply to the brain:
Weakness, vision changes, confusion, dizziness
Severe and uncommon features of hypoglycaemia include:
Convulsion + coma
Skin conditions associated with hyper- and hypothyroidism?
Skin manifestations of hypothyroidism
dry, cold, yellowish skin
dry, coarse scalp hair, loss of lateral aspect of eyebrows
non-pitting oedema (e.g. hands, face)
eczema
xanthomata
Skin manifestations of hyperthyroidism
pretibial myxoedema
clubbing
scalp hair thinning
increased sweating
Pruritus can occur in both hyper- and hypothyroidism
What is MODY?
Maturity onset diabetes of the young, usually <25yo
What is the inheritance pattern of MODY?
Autosomal dominant
What two things might you find in the stem of a question with a patient presenting with undiagnosed MODY?
FH of early onset T2 DM
No ketosis
What do you use to treat MODY?
Sulfonylureas, usually don’t need insulin
Most common sub-classification of MODY and what are they more at risk of?
MODY 3
At increased risk of HCC
Which patients may develop myxoedema coma and how do you treat?
Hypothyroidism
Hydrocortisone and levothyroxine
What is the most common cause of hyperaldosteronism (2/3 of cases)?
And the other cause (1/3)?
Most common: Bilateral adrenocortical hyperplasia
Conn’s syndrome (solitary aldosterone-producing adrenal adenoma)
May also be familial
What is the mechanism by which hyperaldosteronism causes electrolyte abnormalities?
Aldosterone stimulates Na/K ATPase channels to be inserted into the distal convoluted tubules
This causes hypernatraemia (and secondary retention of water) + hypokalaemia