Endocrinology Flashcards
what is meant by catabolic metabolism?
larger molecules are broken down into smaller ones
What is meant by anabolic metabolism?
a larger molecule is made from smaller ones (e.g. storing)
What does autocrine mean?
Acts on the same cell it was released from
What does endocrine mean?
Acts on neighbouring cells
What does exocrine mean?
enters the bloodstream and acts on distant cells
What is meant by ‘neuroendocrine’?
neurons release hormones which enter the blood and travel to their target tissue
What is meant by ‘total plasma hormone’?
Free hormone + protein bound hormone
What connects the hypothalamus and the anterior pituitary?
capillary portal system
Which hormones are secreted by the posterior pituitary?
Vasopressin and oxytocin
Which part of the pituitary is an extension of neural tissue?
Posterior pituitary
Name the amine hormones
Catecholamines (adrenaline, dopamine)
Thyroid hormones
Name the steroid hormones
- Sex steroids
- HCG
- Corticosteroids
What are steroid hormones derived from?
cholesterol
What is a primary endocrine disorder?
disorder arising from a defect in the tissue that secretes that hormones
What is a secondary endocrine disorder?
too much/too little from the pituitary
What is a tertiary endocrine disorder?
Hypothalamic defect
What are the growth drivers in infancy (0-2)?
Nutrition and insulin
What are the growth drivers in childhood (3-11)?
Growth hormone and thyroxine
What are the growth drivers in puberty (12-18)?
Growth hormones and sex steroids
What is the first sign of puberty in girls?
breast budding (Tanner stage B2)
What is the first sign of puberty in boys?
testicular enlargement (Tanner stage G2)
What is the normal age of pubertal onset in boys?
9-14
(below 9 is precocious and above 14 is late)
What is the normal age of pubertal onset in girls?
8-13
(below 8 is precocious and above 13 is late)
Who is offered bariatric surgery?
a BMII ≥ 40
or
BMI ≥ 35 with 1 or more health problems that are likely to improve upon weight loss
which pancreatic cells produce glucagon?
alpha
which pancreatic cells produce insulin?
Beta
Which pancreatic cells produce somastatin?
D cells
What is c-peptide?
a by-product of insulin production
What effect does insulin have on the body?
causes cells to absorb glucose and use it as energy.
causes liver and muscle cells to take up glucose and store it.
What effect does glucagon have on the body?
causes the liver to break down glucose stores (glycogenolysis)
tells the liver to change fats and proteins into glucose (gluconeogenesis
What are the sick day rules for insulin?
Don’t ever stop insulin, check blood glucose levels more often.
When must the DVLA be informed with regards to diabetes?
if you have diabetes managed with medications
If on insulin and likely to be for >3 months
What are the rules regarding driving and long car journeys for those with diabetes?
BM must be checked before driving and every 2 hours whilst driving
Must not drive if BM <5
If BM falls below 5 while driving, you must wait for at least 45 minutes after your BM has surpassed 5mmol/L
What is a healthy, non-diabetic HBA1c?
<42
What is the target HBA1c in diabetics not on medications which carry a hypo risk?
48 or less
What is the target HBA1c in diabetics on medications which carry a hypo risk?
53
what causes T1DM?
Autoimmune destruction of the pancreas
What is MODY?
subset of T1DM occurring in older patients
How often to those with T1DM need to check fngerprick BM?
Finger prick a least 4x daily (before each meal and before bed)
How does c-peptide measure in T1DM?
Low
what causes T2DM?
peripheral tissues become insensitive to insulin (this is insulin resistance) & the pancreas loses its ability to secrete high levels of insulin
Explain the stepwise management of T2DM
Management is stepwise
Diet & exercise
Metformin
Dual therapy (metformin + 1 from table)
Triple therapy (metformin +2 from table)
What are the3 features of DKA
Ketoacidosis, dehydration, potassium imbalance
Which tests cane used to diagnose DKA?
- BM >11
- Ketones > 3
- pH < 7.3
What is the first line treatment of DKA?
Fluid
What must you be careful to avoid causing when treating DKA?
Cerebral oedema
What is the MOA of metformin?
Increases insulin sensitivity
Decreases glucose production by the liver
What are the side effects of metformin?
GI
Lactic acidosis secondary to AKI
What is the suffix of SGLT-2 medications?
-flozin
What is the MOA of SGLT-2 medications?
Increases urinary excretion of glucose
What are the side effects associated with SGLT-2 medications?
Hypoglycaemia & DKA
Weight loss
UTI/thrush/fournier’s
Lower limb amputation
What is the suffix associated with thiazolidinedones?
Increases insulin sensitivity
Decreases glucose production by the liver
What are the side effects associated with thiazolidinedones?
Weight gain
Heart failure
Bone fractures
Bladder cancer
What is the suffix of Sulfonylureas?
-zide
What is the MOA of Sulfonylureas?
Stimulates insulin release from the pancreas
What are the side effects associated with Sulfonylureas?
Weight gain
Hypoglycaemia
What is the suffix associated with DPP-4 inhibitors?
-gliptin
What is the MOA of DPP-4 inhibitors?
Incretin- Increase insulin secretion, inhibit glucagon production, slow absorption from GI tract
What are the side effects associated with DPP-4 inhibitors?
Headache
Pancreatitis
What is the suffix associated with GLP-1
-tide
What is the MOA of GLP-1?
Incretin- Increase insulin secretion, inhibit glucagon production, slow absorption from GI tract
What are the side effects associated with GLP-1?
Reduced appetite
Weight loss
GI
What is the first line antihypertensive in diabetics?
ACE inhibitors
What drug is given in diabetics with CKD if albumin: creatinine > 3mg/mmol
ACE inhibitor
What drug is given in diabetics with CKD if albumin: creatinine > 30mg/mmol
SGLT-2 inhibitor
Name the significant side effects of poorly controlled diabetes?
Vascular
* Retinopathy
* Nephropathy
* Neuropathy
Erectile dysfunction
Depression
What is the difference between cranial and nephrogenic diabetes insipidus?
Cranial DI = lack of antidiuretic hormone
Nephrogenic DI = lack of response to antidiuretic
What causes cranial diabetes insipidus?
Brain pathology
What causes nephrotic diabetes insipidus?
Lithium
High calcium
Low potassium
Polycystic kidney disease
How is diabetes insipidus diagnosed?
Water depravation test
In cranial diabetes inspidus, what result would you expect in
urine osmolality after water depravation
urine osmolality after desmopressin?
In nephrogenic diabetes inspidus, what result would you expect in
urine osmolality after water depravation
urine osmolality after desmopressin?
what is hyperosmolar, hyperglycaemic state?
Hyperosmolality
hyperglycaemia
absence of ketones
How is hyperosmolar, hyperglycaemic state managed?
IV fluids
Describe the hormonal axis for growth hormone
Growth hormone releasing hormone (stimulatory) Somatostatin (inhibitory)
->
Growth hormone (up or down regulated)
->
insulin-like growth factor-1 (IGF-1) from Liver
What are the functions of growth hormone?
Increases blood glucose
Promotes growth
What causes giantism?
Excessive growth hormone prior to closure of long bone epiphysis
What causes acromegally?
Excessive growth hormone after closure of long bone epiphysis
How is acromegaly diagnosed?
IGF-1 test then OGTT
What is the most common cause of excessive growth hormone resulting in acromegaly?
pituitary adenoma
How is a pituitary adenoma managed?
Trans-sphenoidal surgery
What is the first line medical management of acromegallY?
octerotide (somatostatin analogue)
describe the hormonal axis of sex hormones
Gonadotrophin releasing hormone
->
LH/FHS
->
oestrogen
Why do children that have gone through precocious puberty have stunted growth?
long bones fuse early under influence of sex hormones.
describe the hormonal axis of thyroid hormones
Thyrotropin releasing hormone
->
Thyroid stimulating Hormone
->
T3 & T4
Which thyroid cells secrete calcitonin?
clear cell
Which thyroid cells produce and secrete thyroid hormones?
Follicular cells
What are the functions of thyroid hormones?
Metabolism and thermogenesis
Growth
controlling heart, muscle and digestive function
brain development
bone maintenance
How can hyperthyroid be treated?
radioactive iodine
beta blockers (symptomatic)
antithyroid drugs (carbazole)
surgery
Name the two main hyperthyroid presentations
Graves
Toxic multinodular goitre
What antibodies are associated with Graves disease?
Anti-TSH & anti-TPO
How does graves disease present
Classic hyperthyroid signs +
Pre-tibial myxoedema
Exophthalmos
Diffuse goitre
What isotopic multi nodular goitre?
one or more nodules in the thyroid gland that make thyroid hormone without responding to the signal to keep thyroid hormone balanced
How does toxic multi nodular goitre look on nuclerscintigraphy?
Patchy uptake
How does thyroid storm (thyrotoxic crisis) present?
Fever
tachycardia
delirium
hyperthermia
What are the two big side effects of carbamazepine?
agranulocytosis and pancreatitis
What are the three main side effects of propyuracil?
severe liver reactions death
agranulocytosis
What causes hashimotos thyroiditis?
Autoimmune attack of the thyroid gland
What antibody is associated with hashimotos thyroiditis?
Anti-TPO
How is hashimotos managed?
Give titrated levothyroxine (when pregnant, double the dose on 2/7days)
What is the most common cause of hypothyroidism in the developing world?
Iodine deficiency
How much iodine is required per year by the body?
50mg
Name 3 foods high in iodine
milk, fish, seaweed
What is Sheehans syndrome?
Avascular necrosis of pituitary due to massive blood loss
What are the critical findings in myxoedema coma?
Critically low sodium
HYPOthermia
What is Subacute (de Quervain’s) thyroiditis?
Temporary inflammation of thyroid gland triggered by viral infection (e.g. enteroviruses, coxsackie)
Thyrotoxic phase for 3-6 weeks followed by a period of hypothyroidism for 3-6 months
what is the classic finding in subacute (De Quervains) thyroiditis?
PAINFULL goitre
how is subacute (De Quervains) thyroiditis managed?
It itself limiting so treat symptoms
NSAIDs for goitre inflam
B-Blockers for thyrotoxic phase
Levothyroxine for hypothyroid phase
What is the most common type of thyroid cancer?
Papillary
describe the hormonal axis of parthyroid hormones
Serum calcium/phosphate/magnesium levels
->
parathyroid hormone (from PT gland)
->
increased intestinal absorption of calcium
increased kidney reabsorption of calcium
increased calcium reabsorption from bone
What findings you see on skull x-ray in hyperparathyroidism?
Pepper pot skull
How can primary, secondary and tertiary hyperthyroidism be differentiated in blood tests?
How can hyperparathyroidism be managed?
Total parathyroidectomy
Calcimimetics
Describe the hormone axis for prolactin
Thyrotropin releasing hormone ->
prolactin ->
stimulates breast tissue, inhibits ovulation
How is prolactinoma diagnosed?
serum prolactin & MRI
How’s prolacinoma managed?
dopamine agonists (cabergoline or bromocriptine)
Tran sphenoidal surgery
name the area and what it produces
What causes Congenital Adrenal Hyperplasia?
deficiency in the enzyme 21-hydroxylase
How can Congenital Adrenal Hyperplasia present in babies?
Baby GIRLS are born with ambiguous genitalia
can have a salt-losing crisis and become very sick within the first few days of life
Describe the hormonal axis of cortisol
Corticotrophin Releasing Hormone (CRH)
->
Adrenocorticotrophic hormone (ACTH)
->
Cortisol
Describe the difference between Cushing’s disease and Cushing’s syndrome
Cushing’s syndrome = classic Cushing’s caused by everything but a tumour
Cushing’s disease = Cushing’s caused by a tumour
How is Cushing’s diagnosed?
24 hour urinary cortisol or a dexamethasone suppression
What causes Addisons disease?
Autoimmune destruction of the adrenal cortex causes hyposecretion of all adrenal steroid hormones (aldosterone, glucocorticoids and sex steroids)
What is the autoantibody in Addison’s?
autoantibodies against 21-Hydroxylase
What are the presenting features of Addison’s?
Hypotension, hyperkalaemia, hyponatremia
Hyperpigmentation
What diagnostic test is used to identify Addison’s?
Short synacthen test (ACTH stimulation test)
How is an addisonian crisis managed?
100mg IV hydrocortisone
What is the chronic treatment of Addison’s disease?
Hydrocortisone and fludrocortisone
What should people with Addison’s do to their medications when they have a short lived illness or are stressed?
double their glucocorticoid dose
What should people with Addison’s do to their medications when they are seriously ill?
IV Hydrocortisone
What is conn’s syndrome?
Excessive aldosterone from the zona glomerulosa (of the adrenal cortex) usually due to an adrenal tumour
How does conns syndrome present?
hypertension, hyperpigmentation, lethargy
How is conns syndrome tested for?
Aldosterone: Renin ratio
How is conns syndrome managed?
Surgical resection of adrenal adenoma
What is a pheochromocytoma?
neuroendocrine tumour, found in chromaffin cells of adrenal medulla which produces excessive adrenaline
How does phaeochromocytoma present?
Hypertension resistant to anti-hypertensives
headaches
sweating
anxiety
How is pheochromocytoma diagnosed?
Plasma free metanephrines
How is pheochromocytoma managed?
surgical resection of tumour
Alpha blockers
What genetic change is associated with pheochromocytoma?
RET
What is a normal range calcium?
2.2-2.6 mM
What are the two clinical signs of hypocalcaemia?
Trosseau’s sign = The involuntary contraction of the muscles of the hand and wrist that occurs after the compression of the upper arm with a blood pressure cuff
Chovstek’s Sign = The twitching of facial muscles that occurs when gently tapping an individual’s cheek in front of the ear
How is calcium regulated?
Parathyroid hormone (increases calcium)
Calcitrol (increases calcium)
Calcitonin (decreases calcium)
What causes Ricketts (osteomalacia)?
Vitamin D deficiency
Howdoes hypercalcaemia present?
Stones, bones, abdominal moans, psychiatric groans
How is hypercalcaemia managed?
Rehydration
IV Bisphosphonates
What is SIADH?
Increased release of ADH from posterior pituitary
What urine and serum changes does SIADH cause?
high urine osmolality
high urine sodium
low serum sodium
What are the 3 most important causes of SIADH?
Post-operative
SSRI
small-cell lung cancer
Why do you need to replace sodium slowly in patients with chronic hyponatraemia?
more than a 10mmol/L increase in 24 hours can cause osmotic demyelination syndrome
What neoplasms are encompassed by MEN1?
Parathyroid hyperplasia and adenomas
Pancreatic and duodenal endocrine tumours
Pituitary adenoma (prolactinoma)
What neoplasms are encompassed by MEN2A?
MEN1 features + parathyroid hyperplasia
What gene is involved in MEN2A?
RET
What neoplasms are encompassed by MEN2B?
Features of MEN1 & MEN2A + neuromas and skin abnormalities
