Endocrinology Flashcards
What is T1DM?
Characterised by hyperglycaemia due to absolute insulin deficiency; most cases result from autoimmune pancreatic beta-cell destruction in genetically susceptible individuals. Usually presents with acute symptoms or ketoacidosis in childhood or adolescence.
What is T2DM?
Characterised by insulin resistance and relative insulin deficiency; most patients are asymptomatic and are diagnosed through screening (abnormal fasting plasma glucose, HbA1c, and/or oral glucose tolerace test)
How does T1DM present?
Hyperglycaemia (random plasma glucose >11mmol/L)
Polydipsia, polyuria
Usually young age
Weight loss
Blurred vision
Diabetic ketoacidosis (nausea, vomiting, abdominal pain, clinical dehydration, tachypnoea)
Lethargy
Coma or altered mental state (uncommon)
What are the risk factors for T1DM?
Genetic predisposition (family history of autoimmune diseases)
How is diabetes mellitus investigated?
Random plasma glucose (≥11.1 mmol/L confirms diagnosis in presence of symptoms of polyuria, polydipsia, and unexplained weight loss)
Fasting plasma glucose (no caloric intake for >8 hours, ≥7.0 mmol/L)
2-hour plasma glucose (2 hours after 75g oral glucose load, ≥11.1 mmol/L)
HbA1c (reflects degree of hyperglycaemia over the preceding 3 months, ≥6.5% or 48 mmol/L)
How is T1DM treated in children and non-pregnant adults?
Basal bolus insulin (1st line)
Metformin (consider if adult with BMI >25 kg/m^2)
Fixed dose insulin is second line
How is T1DM treated in pregnant women?
Basal bolus insulin
Consider metformin (when insulin resistant, as well as insulin deficient, or BMI ≥25 kg/m^2)
Low-dose aspirin (from 12 weeks till birth of baby - reduces risk of pre-eclampsia)
What are some common symptoms of T2DM?
Asymptomatic
Candidal infections (most commonly vaginal, penile, or in skin folds)
Skin infections (cellulitis or abscesses)
Urinary tract infections (cystitis or pyelonephritis)
Fatigue (may be early warning sign of CVR disease - clinicians should have low threshold for cardiac evaluation)
Blurred vision
What are some uncommon symptoms of T2DM?
Polydipsia and polyuria (only occurs with considerable hyperglycaemia, FPG >16.6 mmol/L and/or HbA1c >95 mmol/mol)
Polyphagia (excessive appetite)
Unintentional weight loss (if marked hyperglycaemia)
Paraesthesias (abnormal sensation, prolonged undiagnosed diabetes resulting in neuropathy)
Acanthosis nigricans (most often associated with obesity)
What are some risk factors for T2DM?
- Older age
- Overweight/obesity
- Gestational diabetes
- Non-diabetic hyperglycaemia (pre-diabetes)
- Family history
- Non-white ancestry
- PCOS (elevated risk; should be periodically screened for diabetes)
- Hypertension
- Dyslipidaemia (especially with low HDL and/or high triglycerides)
- Cardiovascular disease
- Stress
What is the management of T2DM?
FIRST LIFESTYLE
1. Metformin (with SGLT-2 if chronic heart failure or risk of CVD)
Switch to modified release metformin if side effects (e.g. GI)
2. Add sulfonylurea or DPP-4 inhibitor or pioglitazone
What are the side effects of metformin?
GI symptoms: pain, nausea, diarrhoea
Lactic acidosis with severe renal disease or renal failure
What are the contraindications for metformin?
CKD
recent myocardial infarction, sepsis, acute kidney injury and severe dehydration (can cause lactic acidosis)
Alcohol abuse
What are the side effects of SGLT-2?
Glycosuria
Increased urine output and frequency
Genital and urinary tract infections (e.g., thrush)
Weight loss
Diabetic ketoacidosis, notably with only moderately raised glucose
Fournier’s gangrene (rare but severe infection of the genitals or perineum)
What are the side effects of pioglitazone?
Weight gain
Heart failure
Increased risk of bone fractures
A small increase in the risk of bladder cancer
What are the side effects of sulfonylureas?
Weight gain
Hypoglycaemia
What is Addison’s disease?
Destruction of the adrenal cortex and subsequent reduction in the output of adrenal hormones, i.e. glucocorticoids (cortisol) and/or mineralocorticoids (aldosterone)
AUTOIMMUNE
How is cortisol release regulated?
The pituitary gland releases ACTH, which triggers adrenal cortex to secrete cortisol
Elevated cortisol levels suppress ACTH in a negative feedback loop
How does Addison’s disease present?
Fatigue (lethargy, weakness, or tiredness)
Anorexia and weight loss
‘Salt craving’ - hyponatraemia and hyperkalaemia
Hyperpigmentation (MSH is also produced with ACTH, same precursor of POMC)
Nausea, vomiting - may have adrenal crisis
Postural hypotesion
Muscle cramps and joint pains
What are the risk factors for Addison’s disease?
Female sex
Adrenal haemorrhage (patients taking anticoagulants are at increased risk)
Autoimmune diseases
Coeliac disease
Adrenocortical autoantibodies
How is Addison’s disease investigated?
Morning serum cortisol (<140 nanomols/L abnormal)
Plasma ACTH (>12 picomols/L)
U&Es (hyponatraemia, hyperkalaemia)
ACTH stimulation test
How is Addison’s disease treated?
Oral glucocorticoid and mineralocorticoid replacement therapy
(hydrocortisone/cortisone/prednisolone and fludrocortisone)
How is an adrenal crisis treated?
Intravenous hydrocortisone
Saline to correct dehydration and hypotension
Glucose, when necessary, to correct hypoglycaemia
What is Cushing’s disease?
Excessive cortisol production as a result of excessive ACTH from the pituitary gland
What are some causes of Cushing’s syndrome?
Cushing’s disease (pituitary tumour secreting ACTH producing adrenal hyperplasia)
Ectopic ACTH production (e.g. small cell lung cancer)
Adrenal adenoma/carcinoma
Excess glucocorticoid administration
What are the key diagnostic factors of Cushing’s syndrome?
Facial plethora (red, puffy face)
Weight gain, with central obesity and supraclavicular fullness
Violaceous striae
Menstrual irregularities
Hypertension
Glucose intolerance or diabetes mellitus
Premature osteoporosis/unexplained fractures
Acne
Depression
Decreased libido
Proximal muscle weakness
What investigations are considered for Cushing’s syndrome?
Urine pregnancy test to exclude pregnancy
Serum glucose (elevated)
Late night salivary cortisol
24-hr urinary free cortisol
Low-dose overnight dexamethasone suppression test
Plasma ACTH to identify cause of Cushing’s
High-dose dexamethasone suppression test to distinguish between ectopic ACTH and Cushing’s disease
Insulin stress test to differentiate between Cushing’s and pseudo-Cushing’s
U&Es: hypokalaemic metabolic alkalosis
What are the results of the high dose dexamethasone suppression test?
Cushing’s disease: cortisol and ACTH both suppressed
Ectopic ACTH production: cortisol and ACTH both not suppressed
Cushing’s syndrome from other causes: cortisol not suppressed, ACTH suppressed
How is Cushing’s disease treated?
Transsphenoidal pituitary adenomectomy
Somatostatin analogue (pasireotide)
Dopamine antagonist (cabergoline)
Consider post-surgical corticosteroid replacement therapy (hydrocortisone)
How is ectopic ACTH or CRH syndrome treated?
Surgical resection/ablation of tumours producing ACTH or CRH
Ketoconazole or metyrapone before surgery to reduce cortisol before surgery
Chemotherapy/radiotherapy for primary tumour
How is ACTH-independent Cushing’s syndrome due to unilateral adrenal disease treated?
Unilateral adrenalectomy or tumour resection
Ketoconazole or metyrapone before surgery
Consider chemotherapy/radiotherapy for adrenal carcinoma
How is ACTH-independent Cushing’s syndrome due to bilateral adrenal disease treated?
Bilateral adrenalectomy
Permanent post-surgical corticosteroid replacement therapy (hydrocortisone and fludrocortisone)
Medical therapy before surgery (metyrapone/ketoconazole)
What are the key diagnostic factors for hypothyroidism?
Often insidious onset with nonspecific symptoms
Lethargy, weight gain, cold intolerance
Constipation
Menorrhagia
Dry or coarse skin or hair
Change in voice
Bradycardia and hypertension
Eyelid oedema
Goitre
Delayed tendon reflex relaxation
What are the risk factors for hypothyroidism?
Iodine deficiency
Female sex
Middle age
Family history
Autoimmune disorders
Amiodarone use
Lithium use
Radiotherapy to head and neck
Treatment for thyroid disease (e.g. Grave’s)
Post-partum thyroiditis
What are some causes of primary hypothyroidism?
Auto-immune (Hashimoto’s and atrophic thyroiditis)
Iatrogenic (radiotherapy to the neck, surgery, radio-iodide treatment)
Drugs (amiodarone, lithium, anti-thyroid medication)
Congenital
Infiltration of thyroid (amyloidosis, sarcoidosis)
What are some causes of secondary hypothyroidism?
Isolated TSH deficiency
Hypopituitarism (neoplasm, infiltrative, infection and radiotherapy)
Hypothalamic disorders (neoplasms and trauma)
How is hypothyroidism investigated?
Serum TSH (elevated in primary, decreased in secondary, slight elevation in sub-clinical)
Free serum T4 (low, normal in sub-clinical)
Thyroid ultrasonography
How is hypothyroidism investigated?
Serum TSH (elevated in primary, decreased in secondary, slight elevation in sub-clinical)
Free serum T4 (low, normal in sub-clinical)
Thyroid ultrasonography
How is hypothyroidism treated?
Low-dose thyroxine
What signs are indicative of a sellar or parasellar mass causing secondary hypothyroidism?
Papilloedema
Diplopia
Bitemporal hemianopia (decreased peripheral vision)
What is myxoedema coma?
A rare severe form of hypothyroidism with multi-organ failure. There is:
Reduced level of consciousness
Seizures
Hypothermia
Features of hypothyroidism
How is myxoedema treated?
IV levothyroxine
IV hydrocortisone
Correction of metabolic disturbances
What are the causes of thyrotoxicosis?
Grave’s disease (most common)
Toxic nodular goitre
Solitary thyroid nodule
De Quarvain’s thyroiditis (post-viral)
Drugs (amiodarone, lithium, exogenous iodine)
What are the key diagnostic factors for Grave’s disease?
Sweating
Heat intolerance and sweating
Palpitations and fine tremor
Pretibial myxoedema
Diffuse goitre
Menstrual irregularities
Onycholysis (detachment of nail from nail bed)
Exophthalmos
Conjunctival oedema
How is Grave’s disease investigated?
TSH (decreased)
TSH receptor antibodies (positive)
Serum free or total T3/T4 (elevated)
Thyroid scintigraphy: diffuse homogenous increased uptake of radioactive iodine
How does thyroid storm present?
fever > 38.5ºC
tachycardia
confusion and agitation
nausea and vomiting
hypertension
heart failure
abnormal liver function test - jaundice may be seen clinically
How is a thyroid storm treated?
Symptomatic treatment, e.g. paracetamol
Treatment of underlying precipitating event
Beta blockers (IV propranolol)
Antithyroid drugs, e.g. propylthiouracil
Dexamethasone
IV digoxin
How is Grave’s disease treated?
Propranolol for symptomatic control
Antithyroid drugs (carbimazole, propylthiouracil) - p used in 1st trimester of pregnancy
Radioactive iodine ablation
What is a side effect of carbimazole?
agranulocytosis
What is Plummer’s disease?
Toxic multinodular goitre; multiple autonomously functioning nodules, resulting in hyperthyroidism
Almost always benign, but may be malignant
What are the key diagnostic factors of toxic multinodular goitre?
Goitre (usually irregular, rather than smooth)
Heat intolerance, increased appetite, weight loss
Palpitations
Oligomenorrhoea
Stare or lid lag
Tachycardia
Fine resting tremor
Muscle weakness
SOB or choking sensation with large goitre
Pemberton’s sign
What is Pemberton’s sign?
Thoracic inlet obstruction leads to jugular venous distension and facial plethora when arms are extended over the head
How is Plummer’s disease investigated?
TSH (suppressed)
Free T3/T4 (elevated)
Nuclear scintigraphy: patchy uptake
Thyroid ultrasound (cold or warm nodules >1cm in diameter should be considered for further evaluation, e.g. fine needle biopsy)
What is the first line treatment for benign toxic multinodular goitre?
Radioactive iodine therapy (I-131)
Pre-treatment anti-thyroid drugs (thiamazole) - should be started 3-5 days before I-131 treatment and restarted I-131 after treatment
Consider propanolol for patients with increased cardiovascular risk