Endocrinology Flashcards
What are the main components of the endocrine system?
the pituitary, thyroid, parathyroid, adrenal, pancreas, and ovaries/testes
What are the classes of hormones?
Peptides, amines, iodothyronines, cholesterol derivatives and steroids.
What are peptide hormoens like?
Linear or ring structures, vary in length, thwo chains can bind to a carbohydrate stored in granules released in pulses or bursts.
How do peptide hormones act?
They bind to receptors on cell membranes to cause an effect within the cell
What are some amine hormones?
Dopamine norepinephrin and epinephrin, melatonin
How is throxin formed?
Incorporation of iodine intotyrosine to make T3 and T4 iodothyrosines in the colloid
Where are receptors for thyroid hormones?
Int the nucleus
Where are receptors for steroid hormones?
In the cytolasm to bind to a receptor that then enters the nucleus to stimulate transcription
How does vitamin D act?
Enters cells directly to nucleus to stimulate mRNA production
What are the main ways hormones are secreted?
Continuously or pulsatile
What rhythms of secretion are there?
Monthly, day-night
What is the purpose of hormone metabolism?
reduces the function of the hormones
What is around the pituitary gland?
The cella tursica, the cavernous sinus around it
What are metanephrines?
Breakdown products of epinephrines
How much thyroid hormone is protein bound?
99%
What is a direct precursor to estradiol?
Testosterone
What are release inhibiting factors?
Dopamine inhibits prolactin. sometimes there are two types of releasing factors
What are the stimuli of hormone release?
Hmoral stimulus, Hormone stimulating release, neural stimulus
What is hormone receptor induction?
A hormone that stimulates the formation of of more receptors for a certain hormone
What is synergism?
Two hormones act together to the same effect
What is hormone receptor down regulation?
Some hormones reduce the receptors on the cells to reduce the effects of another hormone
What nuclei feed the posterior pituitary?
Paraventriclar nuclesu and supraoptic nucleus
Does the posterior pituitary produce hormones?
No the nuclei in the hypothalamus do
What are the actions of oxcytocin?
release of breastmilk and relaxation of the cervix
How are anterior hormonesreleased?
When the correct releasing hormone is released. or when dopamine is stopped in thae case of prolactin
What are the presentation of dysfuncton of the pituitary?
Tumour mass effects, hormone excess and hormone deficiency
When do you do MRI scan of pituitary?
Only after hormonal tests as lesions can occur in many normal people
Where does growth hormone act?
on the liver to produce insulin-like growth factors which act on the skeleton and extraskeletally, also on increasing fat breakdown and release and also increase carbohydrate metabolism increasing blood glucose leveles
What is the hypohtalamo-pituitary- thyroid axis?
The way the thyroid is controlled to release thyroid hormones
What does thyroid hormone do?
Accelerates food metabolism , heart rate and breathing rate, growth rate, increased fat metabolism
What is the half life of T3?
1 day
What is the half life of T4?
5-7 days
Which thyroid hormone is active?
T3
What is released from adrenal zona glomerulosa?
Mineralocorticoids aldosterone
What hormones are released in stress?
Cortisol, mineralocorticouds and glucoccortiocids
What does FSH do?
Releases oestrogen from granulosa cells, initates spermatogenesis in puberty
What does LH do?
It produces androgens in the theca cells of the ovaries and acts on leidig cells
How to treat high prolactin?
dopamine agonist
What contributes to the obesogenic environment?
Long shift working poor diet, culture that its ok, Less time to exercise
What is hunger?
Need to eat
What is appetiti?
Desire to eat food
What is satiety?
Feeling of fullness
What is the danger with obesity?
Type 2 diabetes hypertensif CHD stroke osteroartheritis obstructive s;ep apnoea and obesity
What is visceral obesity?
Fat around the organs rather than subcutaneous
Why can shift work cause obesity?
It can interrupt the circadian rhythms
What regulates weight?
Environment and genetics of homeostasis
What organs affect apetit?
GI tract, Adipose tissue and the brain
Why do we eat?
We are driven to eat by hormonal changes and thoughts of food and psycological drive to eat
What is the satiety cascade?
sensory, psycological, and physical want to eat including ghrelin. the stomach releases hormones to say you are full. after a meal the adipose releases leptin or insulin that tells the body it doesn’t need to eat yet
What plays a strong role in appetite?
Lateral hypothalamuls the hungercentre and ventromedial hypothalamus the satiety centre
What can increase appetite?
NPY MCH AgRP orexin endocannabinoid
What can decrease appetite?
alpha- MSH CART GLP-1 Serotonin
What does leptin do?
Inhibits NPY and AGRP and stimulates POMC/CART to stop ou wanting to eat
How does the GI tract affect the hypothalamus?
The vagus nerve and Cervical spine SNS afferents to the brain also release of CCK
What produces leptin?
White adipose cells
What does Peptide YY?
Binds to NPY inhibits gastric motility reduces apetite and secreed by neuroendocrine cells in ileum.
What does ghrelin do?
From the stomach, it stimulates growth hormone,
Wat is POMC?
proopiomelanocortin and melanocortin receptors, they are a group of hormones gamma MSH alpha MSH and beta MSH, involved in signalling of satiety
What does a POMC defficiency do?
Make you more overweight
What is agouti related peptide?
Can make you eat more
What is malonyl CoA?
if it is decreased in quantity it increases appetite
Why is diabetes a public health issue?
It is preventable (probably) Mortality, disability( renal failure and blindness, neuropathy and peripheral vascular disease), co-morbidity (physical and mental health conditions) and reduced quality of life
What percentage of diabetes cases are type 2?
90%
What needs to be done for changing prevalence of type 2 diabetes?
Primary prevention reduce incidence, secondary prevention prevalence would increase, tertiary prevention would increase prevalance as more would live longer
What affects getting type 2 diabetes?
exponential relation between BMI and relative risk of type 2 diabetes
Who is at risk of diabetes type 2?
High BMI, sedentary job and lifestyle, diet high in calorie dense food low in fruit vegetables and pulses
What are the aspects of the obesogenic environment?
Physical environment (TV remote controls car culture lifts), Economic environment cheap food is more callorific and fruit and veg is expensive, Sociocultural environment safety fears, family eating patterns
What are the mechanisms make it hard to lose weight?
Pysical more weight makes it harder to lose it, psycological low self-esteem and guilt and comfort eating, socioeconomic less time to work on losing it relationshis etc
What are clinical factors that increase risk of diabetes?
AGE more in men in minorities and with history, gestational diabetes, impared glucose tolerance
What are the screening for abnormal glucose metabolism?
HbA1c random capillary, random venous, fasting venous and oral glucose tolerance test
How do we diagnose diabetes earlier?
Raise awareness of diabetes and possible sy,ptoms in the community, raising awareness of diabetes and possible symptoms i health professionals and identify tose at risk
What includes a diabetes check?
NHS health check every 5 years from 40 - 74
What does nice say to pre-diabetes?
Cost-effective weight loss diet and physical interventions
Why is NHS England investing in type 2 diabetes prevention?
Trials show diet changes can reduce progression from impaired glucose tolerance and could help reverse it in identified patients
How can diabetes be self cared for?
Self monitoring diet exercise drugs education and peer support
Where is glucose from when in the fasting state?
the liver muscle and some from kidney
What is an insulin independent tissue?
the brain and RBC because only use glucose
How is insulin secreted?
Glucose enters the beta cells through GLUT2 transporter which leads to ATP production anc closes channels in membrane and voltage gated calcium does that and insulin is then secreted?
What is glucokinase?
Enzyme that turns leads ATP production without it insulin cannot be released
What is the effect of insulin in muscle and fat?
Bind to receptor causes intracelluar signalling to release GLUT4 transporter to allow glucose entry into the cell
What is the function of insulin?
Surpresses hepatic glucose output through glycogenolysis and gluconeogenesis. increases glucose uptake in tissue and supresses muscle breakdown and lipolysis
What does glucagon do?
Increases hepatic glucose output and reduce peripheral glucose uptake and stimulate the release of glucose from peripheraltissues
What counteracts insulin effect?
Glucagon, adrenaline and cortisol and frowth hormoens
What is diabetes mellitus?
disorder of carbohydrate metabolism characterised by hyperglycaemia
What causes morbidity and mortality in diabetes?
Acute hyperglycaemia which can lead to diabetic ketoacidosis o hyperosmolar coma, chronic hyperglycaemia can lead to tissue damage.
What are complications with diabetes?
Diabetic neuropathy peripheral usually, nephropathy, diabetic retinopathy, CHD and stroke
What are the types of diabetes mellitus?
Type1, type 2, maturity onset diabetes of youth monogenic, pancreatic, endocrine, malnutritional diabetes
What is diabetes diagnosis?
Symptoms(thirst, polyurea) plasma glucose>11. fasting plasma>7 no symptoms- GTT HbA1c
What is HBA1c?
measure of blood sugar over the last few weeks
What is the pathogenesis of type 1 diabetes?
insulin deficiency disease characterised by loss of beta cells due to autoimmune destruction. Beta cells express HLA and can be attacked by the body
What happens without insulin in a diabetic?
continual breakdown of liver glycogen, unrestrained lipolysis and muscle breakdown. releases hepatic clucse output, as glucose conc goes high at 10mM/L then it is excreted but gives symtoms
What happens in long term with uncontrolled diabetes?
Increased stress hormones, catabolic state leading to ketoacidosis and loss of weight,
What causes type 2 diabetes?
Genetics and environment lead to impared insulin secretion and insulin resistance. Insulin requirements are increased and it causes resistance and eventually exhaustion of cells
Why does being obese cause problems for type 2 diabetes?
Increased production of insulin
What is main difference in type 2 and 1 onset?
The type 1 diabetes is quick onset type 2 is much slower
What happens in glucose metabolism in type 2?
Insulin is detectable, reduced muscles and fat uptake after eating, failure to surpress lipolysis and high circulating free fatty acids ad abnormally high glucose after a meal and low levels of inulin stop muscle breakdown and no ketone production to excess like in type 1
What is the key point fo type 1 diabetes?
One defect no insulin
What is the key point for type 2 diabetes?
Two defects impaired insulin secretion and hepatic and muscle/ fat insulin resistance
What are the principals of treatment for dibetes?
Control of symptoms, prevention of acute emergencies, ketoacidosis, hyperglycaemic hyperosmolar states, identification and prevention of long term complications, control CHD risk
What is treatement type 2 diabetes/
Lose weight, and exercise but doesn’t work very often in practice as people don’t want to change. Target hypertenion lipid and glucose levels
What are sulphonylureas?
Stimulate insulin release by binding to beta cell receptors, effectiv in reducing sugar levels, but can cause hypoglycaemia, it can increase weight. Use gliclazide normally be careful of real imparement
What are thiazolidinediones (pioglitazone)?
Bind to nuclear receptor to change genes surrounding glucose uptake improve insulin sensitivity. Need insulin for a theramutic rarely used because increase weight increase risk of heart failure and risk fractureseffect,
What does GLP1 do?
Stimulates insulin secretion, reduces glycogen increeases beta cell mass and enhances glucose disposal but it is broken down very fast
How are GLP1 extende in duration?
Inhibit DPP or modify the shape so it isnt broke down as fast
What are GLP analogues?
Exenatide, liraglutide, lixisematide, dulaglutide, semaglatide
What is SGLT2?
Produced in kidney to assist glucose reabsorption.
What do SGLT2 inhibitors do?
They make you wee more sugar out.
What do you chose in type 2 diabets?
Metformin, then DPP-IV, GLP1 analogues and SGLT2 inhibitors as second line
What are the types of insulin used?
long acting and short actin
How is T1DM managed with insulin?
Basal bolus of insulin to mimic physiology
What is the challenge?
pre-meal rapid acting boluses adjusted according to pre-meal glucose and carbohydrate content of food to cover meals. Basal insulin should control blood glucose in between meals and during the night basal insulin can be giben twice daily or sometimes once a day adjusted to maintain fasting blood glucose between 4-7 mmol/L
How many type 2 diabets need insulin?
about 50% will eventually need it
How are T2 diabetes treated with insulin?
Basal insulin to keep the levels lower and less hypoglycaemia at night,
What is the problem with premixed insulin?
Have both long acting and short acting. Doesn’t cover meals can’t change for over night
What is the low plasma glucose level 1?
less than 3.9
What is low plasma glucose level 2?
less than 3.0 mmol/L
What is non-sever hypoglycaemia?
patient has symptoms but can self-treat and cognotive function is mildly impared.
What is sever hypoglycaemia?
Patient has impared cognitive function to require external help to recover this is level 3
How common is hypoglycaemia?
in type 1 its very high 1 episode per patient per year. in type 2 diabetes 0.3 per person per year
What are the side effects of hypoglycaemia?
Brain cognitive dysfunction siesure, coma psychological effects, heart increased risk of ischaemia and arrhythmias also fall driving accidents inflammation blood coagulation abnormalities endothelial dysfunction
What is problem with insulin treatment?
Can gain lots from good control but can cause hospitalisation and damage when it goes wrong
What are the symptoms of hypoglycaemia?
Autonomic, tremblin plapations, sweating anxiety hunger from adrenaline release, neuroglyopenic hard to concentrate confused vision changes dificulty speaking, nausea and headach
why can diabetics get hypoglycaemia but non-diabetics can’t?
insulin stops being secreted after insulin lowers, and in diabetes lose glucagon response and adrenaline level activation is much lower
What is the defence against high insulin levels?
Glucagon, adrenaline,
What are the risk factors for hypoglycaemia in a diabetic?
Long duration of diabetes, age, alcohol, sleeping increased physical activity
How can patientsbe screened for hypoglycaemia?
Low HbA1c previous history, long duration of diabetes, impared awareness of hypoglycaemia big insulin dose, impared renal function and physical activity
What are prevention strategies of hypoglycaemia?
discuss hypoglycaemia risk factors educate families and report hypoevents
How to treat hypoglycaemia?
Recognise the symptoms, confirm it with blood glucose, treat with 15g fast acting carbohydrates, retest in 15 minutes to ensure blood glucose is back to normal then eat again
What is the action of parathyroid hormone?
Increased calcium reabsorption in the kidney, descreases phosphate reabsorption and increased hydroxylantion of Vit D, Bone remodelling increased, no direct effect on GI but vit D does
What is serum calcium?
1.1mmol/L
Why should calcium be controlled?
It is involved with contraction of muscle including the heart
What are the options when you see a change in PTH levels?
Could be part of the normal response to low calcium or it could cause a calcium imbalance
what can affect calcium levels in the blood?
The quantity of calcium or having varying levels of albumin in the blood
How is the total calcium calculated?
total serum calcium +0.02*(40-serum albumin)
What can hypocalcaemia cause?
tingling Paresthesia, muscle spasm, seizures basal ganglia calcification cateracts and ECG abnormalities long QT intervals
What is Trousseau’s sign ?
inflate the blood pressure cuff above systolic and leave for 5 minutes and muscles tense up
What is Chvostek’s sign?
Tapping on facial nerve causes spazm
What can cause hypocalcaemia?
Osteomalacia, surgical, radiation often for cancer treatments, Genetic syndromes, genetic problems, autoimmune disorders, infiltration of metal (haemochromatosis and wilsosns too much iron and copper) also Mg deficiency
What are stages of vitamin D production?
Formation in skin to 7-dehydroxycholesterol and then in the liver it is 25 hydroxylates then 1,25 hydroxylated in the kidney
What are Di George?
Devevelopmental abnormality of third and 4th branchial pouches hypoparathyroidsism thympic aplasis, immunodeficiency cardiac defects cleft palate and abnormal facies
What is pseudohypoparathyroidism?
resistance to parathyroid hormone type 1 albright hereditary osteodystrophy. 4th finger sign
What can can cause artificially high Calcium levels?
Leaving touniquet on for too long or old haemolysed blood sample, also albumin levels
What are the sumptoms of hypercalcaemia?
Thirst, polyuria, nausea, constipation, confusion coma and kidney stones, Short QT interval
What are the causes of hypercalcaemia?
Malignancy bone metasticies, primary hyperparathyroidism very common. Thiazides, thyrotoxoxosis, sarcoidosis, familial hypocalciuric/benign hypercalcaemia, immobilisation, Milk-Alkali, adrenal insufficiency, Phaechromocytoma
What are are consequences of primary hyperparathyroidism?
Bones osteitis fibrosa cystica osteoporosis, kidney stones, psychic groans confusion and abdominal moans constipation acute pancreatitis
What causes most primary hyperparathyroidism?
80% from single benign adenoma15-20 four gland hyperplasia. MEN I or II rarely malignant
How can surgical damage cause hypocalcaemia?
Removal of parathyroid by accidnet
Why can autoimmune disorders cause hypoparathyroidism?
Polyglandular type 1 attacks the cells of parathyroid
How can infiltration cause hypoparathyroidism?
Build up of copper and iron in the parathyroid
What is the need for magnesium in the parathyroid?
Helps with vesicular transport of PTH hormone out of Parathyroid cells
What is pseudohypoparathyroidism?
End organ ressistance to PTH
How do malignancies cause hypercalcaemia?
cancer damages bone that releases calcium, secreted parathyroid related protein, lymphoma from macrophages overprodicuing vitamin D
How do thyrotoxicosis cause hypercalcaemis?
Bone is turned over too fast
What is problem with hypocalciuric/benign hypercalcaemia?
It can’t be fixed by removing parathyroids