Endocrinology Flashcards
explain the pathophysiology of type 1 diabetes
insulin deficiency, due to autoimmune destruction of insulin-secreting pancreatic beta cells
explain the pathophysiology of type 2 diabetes
insulin resistance develops - body can no longer produce enough insulin to cope with the high levels of glucose entering the body so the cells become resistant to insulin’s effects.
there is hypersecretion of insulin, by a depleted number of beta cells, so the insulin levels are increased by not enough to control glucose homeostasis.
hyperglycaemia and lipid excess are toxic to beta cells so insulin secretion then drops.
what is the classical triad of symptoms for a presenting type 1 diabetic? what causes each of these
polyuria - due to osmotic diuresis from blood glucose exceeding the tubular reabsorption capacity.
thirst - due to fluid and electrolyte loss.
weight loss - fluid depletion and accelerated breakdown of fat and muscle.
give 3 complications a type 1 diabetic may present with
staphylococcus skin infections, retinopathy, polyneuropathy, erectile dysfunction, arterial disease e.g. MI.
if you take a random blood glucose as part of general monitoring/while testing for something else, and it comes back at 23mmol/L, what do you need to confirm a diagnosis of diabetes?
repeat the blood glucose test at another time.
one result is enough if the patient is symptomatic.
what investigation is used to measures long term glucose control? what are the normal and diagnostic values?
HbA1c - glycosylated haemoglobin - glucose is taken up by haemoglobin and remains in blood for 8-12wks - high blood glucose over that period shows up as a raised HbA1c.
diagnostic value is >48mmol/mol.
what is the WHO diagnostic criteria for diabetes mellitus ?
hyperglycaemic symptoms - polyuria, polydipsia, unexplained weight loss, visual blurring, genital thrush, lethargy AND:
fasting plasma glucose >7.0mmol/L OR.
random plasma glucose >11.1 mmol/L.
describe the management of type 1 diabetes, apart from insulin therapy.
risk factor management (esp. BP control!).
education, diet and exercise e.g. educate on self-adjusting doses.
frequent self-monitoring of blood glucose and long-term monitoring of HbA1c.
what are the steps of tablet treatment for a type 2 diabetic?
1) lifestyle changes and metformin
2) add DPP-1 inhibitor (gliptin)/sulfonyurea/glitazone.
3) add any of the above not used
4) start insulin therapy alongside other medications.
how does metformin work?
reduces rate of gluconeogenesis, reducing hepatic glucose output.
increases insulin sensitivity.
decreases absorption of glucose in GI tract.
NO weight gain or hypos, but can cause lactic acidosis.
how does sulfonylurea work?
binds to channels on beta cells to increase fusion of insulin granulae with cell membrane.
INCREASES INSULIN SECRETION.
can cause hypoglycaemia and weight gain.
how do glitazones work?
interact with PPAR-gamma, which regulates lipid metabolism and insulin action - fatty tissue is redistributed and lower free fatty acid levels - promotes glucose consumption by muscles.
what are the differences in onset between type 1 and type 2 diabetes?
type 1 - adolescent onset usual.
type 2 - onset usually >40yrs.
type 1 is linked to HLA D3 and D4, type 2 has no HLA association.
what are the differences in how type 1 and type 2 diabetes present?
type 1 will present with polydipsia, polyuria, weight loss, ketonuria etc.
type 2 presents asymptomatically (picked up on blood test), or with complications e.g. MI.
what lifestyle factors is type 2 diabetes associated with?
obesity, lack of exercise, calorie and alcohol excess.
list some possible causes of DM
drugs - steroids, anti-HIV drugs, antipsychotics, thiazides.
pancreatic - pancreatitis, surgery, trauma, pancreatic destruction (haemachromatosis, CF), pancreatic cancer.
Cushing’s disease.
Acromegaly.
Phaeochromocytoma.
Hyperthyroidism.
Pregnancy (gestational diabetes).
give 3 risk factors for type 2 DM
overweight/obese. central adiposity. Asian background. Age >40yrs. FHx. gestational diabetes.
give 3 general measures that should be undertaken in diabetes mellitus
inform DVLA.
foot care.
exercise.
diet - low in sat fats and sugar, high in starchy carbs.
avoid binge-drinking - delayed hypo.
educate on managing hypo - sugary drinks, dextrose tablets.
describe the common insulin options used to treat diabetes mellitus
1) ultra-fast acting (Novorapid) injection at start of meal.
2) isophane insulin - peak at 4-12h.
3) pre-mixed insulins with ultra-fast components.
4) long-acting recombinant human insulin analogues (insulin glargine/detemir) - used at bedtime, no peak so avoids nocturnal hypos.
give examples of possible injection sites for insulin. why is it important they are rotated regularly?
outer thigh, abdomen, arm.
rotating reduces risk of infection and lipohypertrophy (lipohypertrophy).
give 3 possible complications of diabetes mellitus
infection/lipohypertrophy at injection sites. MI, stroke. nephropathy - microalbuminuria. retinopathy. cataracts. diabetic foot. neuropathy. hypoglycaemia - due to insulin spikes, skipped meals, incorrect dose adjustment for exercise etc.
describe the symptoms of hypoglycaemia
autonomic - sweating, anxiety, hunger, tremor, palpitations, dizziness.
neuroglycopenic - confusion, drowsiness, visual trouble, seizures, coma
how would you treat hypoglycaemia?
oral sugar and long-acting starch (e.g. toast).
IV glucose if can’t swallow.
what is a hypoglycaemic coma? how would you treat it?
rapid onset of hypoglycaemia preceded by aggression, sweating, high pulse, seizures - leading to loss of consciousness.
treat with IV glucose - should recover promptly.
sugary drinks and a meal once conscious.
give 3 symptoms of diabetic ketoacidosis
lethargy, nausea, vomiting, anorexia, abdo pain, polyuria, polydipsia, weight loss, breathlessnesss
give 3 signs of diabetic ketoacidosis
dehydration, reduced consciousness, ketotic breath (pear drops), Kussmaul breathing (deep and laboured).
what causes diabetic ketoacidosis?
there’s an excess glucose, but due to lack of insulin this can’t be taken up by cells to be metabolised - body pushed into starvation-like state.
ketoacidosis is the only alternative metabolic pathway.
results in severe acidosis.
does diabetic ketoacidosis generally occur in type 1 or type 2 diabetics?
type 1 - rare in type 2.
give 3 possible triggers of DKA
infection e.g. UTI.
surgery, MI, pancreatitis, chemo, antipsychotics, wrong insulin dose/non-compliance
what would you find on investigation of a patient presenting with DKA?
acidaemia - blood pH less than 7.3
give 3 possible complications of DKA
cerebral oedema, aspiration pneumonia, hypokalaemia, hypomagnesaemia, hypophosphataemia, thromboembolism
how would you treat DKA?
rehydration - fluids.
IV insulin infusion ± potassium replacement.
is hyperglycaemic hyperosmolar non-ketotic (HONK) state/coma more likely to affect a type 1 or type 2 diabetic?
type 2
how would a hyperosmolar hyperglycaemic state present?
longer history (1wk) with marked dehydration and raised glucose.
stupor/coma.
impairment of consciousness is directly related to degree of hyperosmolality.
how would you manage a HONK patient?
rehydrate slowly with IV saline.
replace potassium when urine flowing.
if blood glucose not falling with rehydration, use insulin.
what are patients with HONK at particular risk of?
occlusive events - focal CNS signs, chorea, DIC, leg ischaemia, DVT.
how might diabetic neuropathy present? how would you manage it?
stocking and glove distribution of loss of sensation, absent ankle jerks, deformities. may develop ulcers and ischaemia if there’s accompanying peripheral vascular disease.
special foot care and diabetic shoes needed.
control pain with:
paracetamol => amitriptyline => gabapentin => baclofen
explain the disease process underlying Graves’ disease
autoimmune - serum IgG antibodies bind to TSH receptors causing thyroid growth and overstimulation of thyroid hormone
name 3 triggers for the development of Graves’ disease
stress, infections, childbirth, other autoimmune diseases
if you measures TSH and T3/T4 in Graves’ disease, what would you expect to see?
suppressed TSH, high T3/T4.
also TSH receptor antibodies.
give 2 symptoms and 2 signs of thyroid eye disease
symptoms - eye discomfort, grittiness, increased tear production, photophobia, diplopia, decreased acuity.
signs - exophthalmos, proptosis (bulging), conjunctival oedema, lid lag, lid retraction, papilloedema, ophthalmoplegia, loss of colour vision
give 4 clinical features of hyperthyroidism
weight loss diarrhoea heat intolerance increased appetite palpitations tachycardia irritability tremor hyper-reflexia lid lag oedema sweating
eye disease in Graves’
list 3 causes of hyperthyroidism, not including Graves disease
toxic multinodular goitre, toxic adenoma, amiodarone, post partum thyroiditis, iodine excess (e.g. contaminated food, contrast media).
describe the production and general action of thyroid hormones
stimulated by TSH produced by pituitary gland.
thyroid gland secretes mostly thyroxine (T4) + some of the active triiodothyronin (T3).
most T3 is produced by peripheral conversion of T4.
gland requires iodine to produce the hormones.
act on nearly every cell, controlling metabolism - increase BMR.
what would you see on blood tests in hyperthyroidism?
TSH low - suppressed.
raised T4 and T3.
thyroid autoantibodies seen in Graves’.
how would you treat hyperthyroidism?
beta blockers (propranolol) for rapid symptom control. anti-thyroid drugs - carbimazole.
radioiodine ablation, thyroidectomy.
what does a thyroidectomy risk?
hoarseness due to damage to recurrent laryngeal nerve.
hypoparathyroidism.
name 2 possible complications of hyperthyroidism
heart failure, angina, AF, osteoporosis, ophthalmopathy, gynaecomastia
what is thyroid acropachy? give 2 features
a dermopathy associated with Graves’ disease.
CLUBBING, painful digit swelling
give 4 symptoms of hypothyroidism
weight gain decreased appetite lethargy low mood cold intolerance constipation hoarse voice decreased memory/cognition cramps and weakness
give 4 signs of hypothyroidism
BRADYCARDIC: Bradycardia. Reflexes relax slowly. Ataxia Dry thin hair/skin Yawning/drowsy/coma Cold hands ± low temp. Ascites ± non-pitting oedema ± pericardial effusion. Round puffy face/double chin/obese. Defeated demeanour Immobile CCF (congestive cardiac failure)
give 3 causes of hypothyroidism
Hashimoto’s thyroiditis, iodine deficiency, post-thyroidectomy/radioiodine treatment,
primary atrophic hypothyroidism, antithyroid drugs.
what would you find on investigation of a patient with hypothyroidism?
high TSH, low T3/free T4.
how would you treat hypothyroidism?
levothyroxine (T4) - given for life, monitor TSH levels, increase dose when pregnant
what is Hashimoto’s thyroiditis?
a primary, autoimmune thyroiditis. cause hypothyroidism (or euthyroidism), with goitre that is due to lymphocytic and plasma cell infiltration. more common in women aged 60-70yrs.
give 3 diseases associated with hypothyroidism
autoimmune hypothyroidisms are associated with other autoimmune disease - type 1 DM, Addison’s, pernicious anaemia.
Turner’s and Down’s syndromes.
CF, primary biliary cirrhosis, ovarian hyperstimulation, pregnancy problems (eclampsia, anaemia, prematurity, low birthweight etc).
what tumour marker would you look for to confirm a diagnosis of thyroid carcinoma?
thyroglobulin
where are the common metastases sites for papillary and follicular carcinomas?
lungs and bones
how would you manage a thyroid carcinoma?
total thyroidectomy and lymph node clearance ± radioiodine ablation
what are the different types of thyroid cancer?
papillary, follicular, medullary.
give one physiological and one pathological cause of goitre
physiological - puberty, pregnancy.
pathological - iodine deficiency, high dose of carbimazole/propylthiouracil
if goitre became painful, what could be the cause?
bleeding, thyroiditis, malignancy
give 2 indications for surgery in goitre
malignancy, pressure symptoms, toxic nodule, cosmetic reasons
what does the adrenal cortex produce, and what do they do?
steroids.
Salt - Sugar - Sex (it gets sweeter as you go deeper)
mineralocorticoids (e.g. aldosterone) - control sodium and potassium balance.
glucocorticoids (e.g. cortisol) - affect carbohydrate, lipid and protein metabolism.
androgens - sex hormones.
how is the adrenal cortex stimulated to produce cortisol/androgens?
corticotrophin-releasing factor (CRF) from hypothalamus stimulates ACTH secretion from pituitary - stimulates cortisol and androgen production.
what is Cushing’s syndrome?
clinical state produced by chronic glucocorticoid excess + loss of normal feedback mechanisms of the hypothalamo-pituitary-adrenal axis and loss of circadian rhythm of cortisol secretion
what is the main cause of Cushing’s syndrome?
oral steroids
what are the two classes of causes of Cushing’s syndrome?
increased circulating ACTH from a pituitary/ectopic tumour with glucocorticoid excess - ACTH dependent.
primary excess of cortisol secretion by an adrenal tumour or nodular hyperplasia with ACTH suppression - ACTH independent.