Endocrinology Flashcards
Define obesity
Abnormal or excessive fat accumulation which poses a risk to health.
BMI > 30.
What are some potential consequences of obesity ?
- Type II Diabetes
- Hypertension
- Coronary artery disease
- Stroke
- Osteoarthritis
- Gout
- Obstructive sleep apnoea
- Carcinoma (breast, endometrium, colon, prostate)
What are 5 risk factors for obesity
- Hypothyroidism
- Hypercortisolism
- Corticosteroid therapy
- Diet high in sugar and fats
- High alcohol intake
What is leptin and its action?
A hormone released by adipocytes which switches off appetite and stimulates the immune system. Leptin levels in the blood increase after eating and decrease after fasting.
What is ghrelin and its action?
A hormone released by endocrine cells of the stomach which stimulates growth hormone release and appetite. Blood levels are high when fasting and fall after eating.
What is the action of insulin?
- suppresses hepatic glucose output (decreases glycogenolysis and gluconeogenesis)
- increases glucose uptake into muscle and fat
- suppresses lipolysis and muscle breakdown
What is the action of glucagon?
- increases hepatic glucose output (increases glycogenolysis and gluconeogenesis)
- reduce peripheral glucose uptake
- stimulate peripheral release of gluconeogenic precursors (glycerol, AAs) - increases lipolysis and muscle breakdown
What other hormones have counterregulatory effects similar to glucagon?
adrenaline
cortisol
growth hormone
What is diabetes mellitus?
A disorder of carbohydrate metabolism characterised by hyperglycaemia.
How does DM cause morbidity and mortality?
- Acute hyperglycaemia (leads to diabetic ketoacidosis and hyperosmolar hyperglycaemic state if untreated)
- Chronic hyperglycaemia leading to tissue complications
- Side effects of treatment - hypoglycaemia
What random plasma glucose level with symptoms indicates diabetes mellitus?
> 11mmol/l
What fasting plasma glucose value indicates diabetes mellitus?
> 7mmol/l
What is GTT and what are the fasting and 2hr values that indicate diabetes mellitus?
GTT = Glucose tolerance test
GTT (75g glucose) fasting > 7mmol/l
or 2hr value >11mmol/l (repeated on 2 occasions)
What is HbA1c and what value is associated with diabetes mellitus?
HbA1c = glycated haemoglobin, a form of haemoglobin used to measure the average haemoglobin-associated glucose in blood over the last three months, HbA1c >48mmol/mol (6.5%) is seen in patients with diabetes mellitus
What are the types of diabetes mellitus?
- Type I
- Type II
- Maturity onset diabetes of youth (MODY)
- Pancreatic diabetes
- Endocrine diabetes (result of acromegaly/cushings)
- Malnutrition related diabetes
What is Type I diabetes?
An insulin deficiency disease characterised by loss of beta cells due to autoimmune destruction.
What is the cause of Type I diabetes?
Beta cells express HLA (human leukocyte antigen) which activates a chronic cell mediated immune process leading to chronic ‘insulitis’ and consequently insulin insufficiency
What are the risk factors for T1 Diabetes?
- HLA DR3 and DR4 and islet cell antibodies
- Other autoimmune diseases
- Environmental infections (e.g. viruses)
What is the typical presentation/symptoms of Type I DM?
Young lean pt
- polydipsia
- nocturia/polyuria
- glycosuria
- polyphagia (excessive eating) + weight loss
- excessive tiredness
What is the treatment for T1DM?
Basal Bolus Insulin
- basal = longer acting to maintain stable insulin levels throughout day
- bolus = faster acting, 30 mins preprandial to give “insulin spike”
What is diabetic ketoacidosis?
Result of too much gluconeogenesis so that glucose is converted to ketone bodies which are acidic. Caused by poorly managed T1 DM or from infection/illness
What are the signs of diabetic ketoacidosis?
T1DM symptoms +…
- Kussmaul breathing (deep laboured breaths to compensate for increased CO2)
- Pear drop breath (breath smells fruity due to ketones)
- Reduced tissue turgor, hypotension + tachcardia
What are the diagnostic blood concentrations of ketones, glucose and acid in DKA?
Ketones >3mmol/l
Random plasma glucoe >11.1mmol/l
pH<7.3 or <15mmol HCO3-
What is the treatment for DKA?
- in an emergency ABCDE
- 1st line always fluid (dehydration is most likely cause of death)
- then insulin (+ glucose and postassium)
What are the potential complications of DKA?
- cerebral oedema
- adult respiratory distress syndrome
- thromboembolism
- aspiration pneumonia (drowsy/comatose patients)
- death
Why can insulin treatment for DKA cause hypokalaemia and why is this dangerous?
insulin decreases potassium levels in the blood by redistributing K+ into the cells via increased Na/K pump activity causing low serum K+ levels –> hypokalaemia
low levels of K+ can cause arrhythmia, weakness (as the heart and muscles can struggle to contract)
What is Type II Diabetes Mellitus?
Insulin resistance and impaired insulin secretion due to a combination of genetic predisposition and environmental factors (obesity and lack of physical activity)
What are the risk factors for T2DM?
genetic link, smoking, obesity, sedentary lifestyle
What is the pathophysiology of T2DM?
Peripheral insulin resistance (e.g. malfunctional insulin intracellular activation pathway) leads to decrease GLUT4 receptor expression + minor destruction of pancreatic islets.
This results in hyperglycaemia with increased insulin demand from depleted beta cell population.
What is the typical presentation and symptoms of T2DM?
Obese, hypertensive, older patient
- persistant hyperglycaemia
- polydypsia
- nocturia + polyuria
- glycosuria
- blurred vision
- recurrent infections
- tiredness
- acanthosis nigiricans (dark pigmentation of skin folds) suggesting insulin resistance
What are IGT and IFG?
IGT = Impaired Glucose Tolerance
IFG = Impaired Fasting Glycaemia
Conditions of slightly elevated blood glucose but not high enough to be classed as diabetic so are called prediabetic states
What are the FPG and OGTT values in IGT?
FPG >/= 6mmol/l
2hr OGTT 7.8-11mmol/l
What are the FPG and OGTT in IFG?
FPG 6.1-6.9mmol/L
2hr OGTT <7.8mmol/l
What is the treatment for T2DM?
- Lifestyle changes (weight loss, exercise, diet changes)
- medications to control BP, blood glucose + lipids
- Metformin (1st line)
- DPP-IV inhibitors (vildagliptin, sitagliptin)
- GLP analogues (exenatide, liraglutide)
- SGLT-2 inhibitors (empagliflozin, canagliflozin)
- Sulphonylureas (gliclazide, glibenclamide)
- Thiazolidinediones (pioglitazone)
What is the action of metformin?
improves action of insulin in reducing blood glucose
What is the action of GLP-1 analogues?
They extend the duration of GLP-1 which is a gut hormone that stimulates insulin release and reduces appetite. GLP-1 analogues extend the duration of GLP-1 action and so lower blood glucose and help to reduce weight and cardiovascular disease.
What is the action of DPP-IV inhibitors?
DPP-IV is an enzyme which destroys incretin, a hormone which helps the body reduce blood glucose. DPP-IV inhibitors stop the destruction of incretin and so help lower blood glucose however the effect is not highly significant and has no effect on CVD or weight.
What is the action of SGLT2 inhibitors?
They inhibit the sodium glucose transporters in the renal proximal tubules, blocking the reabsorption of glucose and so increasing glucose excretion and lowering blood glucose levels.
What are the actions of sulphonylureas?
- Stimulate insulin release by binding to beta-cell receptors
- improve glycaemic control at the expense of significant weight gain
*risk of hypoglycaemia
What are the actions of thiazolinediones?
- Bind to the nuclear receptor PPARy and activate genes concerned with glucose uptake and utilisation and lipid metabolism
- improve insulin sensitivity
- need insulin for therapeutic effect
What is MODY?
Maturity-onset diabetes of the young
- includes several forms of diabetes with monogenetic defects of beta-cell function (impaired insulin secretion)
- usually manifesting as mild hyperglycaemia at a young age and inherited in an autosomal-dominant manner
What is C-peptide and why is it measured?
A peptide which connects the alpha and beta pro-insulin chains. It is measured to show whether there is insulin being produced by the body or only synthetic insulin in the blood.
What is permanent neonatal diabetes?
Inability to produce insulin caused by mutations in the genes encoding the beta cell ATP sensitive potassium channel (Kir6.2 and SUR1). They prevent closure of the channel so insulin cannot be secreted.
What is maternally inherited diabetes and deafness (MIDD)?
Mutation in mitochondrial DNA which causes loss of beta cells and presents similarly to Type 2 diabetes.
What is lipodystrophy?
Selective loss of adipose tissue associated with insulin resistance, dyslipidaemia, hepatic steatosis (fatty liver disease), hyperandrogenism, PCOS
What is hypoglycaemia?
abnormally low blood glucose
What are the symptoms of hypoglycaemia?
dizziness, feeling faint, loss of consciousness
What is the treatment for hypoglycaemia?
IV glucose
What are the most common causes of hypoglycaemia?
- result of the sulfonylureas (stimulate insulin production + secretion) or insulin used to treat diabetes
- non-diabetic causes = liver failure, Addison’s disease (adrenal insufficiency)
What is HHS?
Hyperosmolar Hyperglycaemic state - often precipitated with infection
What are the symptoms of HHS?
urination,
thirst
nausea
dry skin
disorientation and, in later stages, drowsiness and a gradual loss of consciousness.
How is HHS diagnosed?
- heavy glycosuria
- increased plasma osmolarity (>30mmol/L) w/ hyperglycaemia
- No ketonuria/hyperketonemia
What is the treatment for HHS?
- First insulin with potassium + glucose
- then IV fluid (0.9% saline)
- LMWH (low molecular weight heparin) to anticoagulate patient as they have thicker blood
How is insulin introduced in T2DM?
Basal insulin initially followed by prandial insulin when necessary
What is pre-mixed insulin?
Both basal and prandial components in a single insulin preparation which can cover insulin requirements through most of the day.
What is level 1 hypoglycaemia?
Alert value:
Plasma glucose <3.9 mmol/l and no symptoms
What is level 2 hypoglycaemia?
Serious biochemical:
Plasma glucose <3.0 mmol/l
What is the difference between non-severe and severe symptomatic hypoglycaemia?
With non-severe hypoglycaemia the patient can self-treat and cognitive function is only mildly impaired whereas with severe there is impaired cognitive function to require external help to recover.
What are the symptoms of developing hypoglycaemia?
Autonomic - palpitations, trembling, sweating, anxiety, hunger
Neuroglycopenic - difficulty concentrating, confusion, weakness, drowsiness, vision changes, difficulty speaking, dizziness
Non-specific - nausea, headache
What is impaired awareness of hypoglycaemia?
Following several hypoglycaemic episodes the body’s sensitivity to hypoglycaemia is reduced and the protective mechanisms of inhibiting insulin secretion, releasing glucagon and adrenaline are impaired so there is increased risk of severe hypoglycaemia.
What are the causes of hypoglycaemia?
- long term diabetes
- tight glycaemic control with repeated episodes of non-severe hypoglycaemia
- increasing age
- use of drugs (prescribed, alcohol)
- sleeping (reduced ability to produce protective measures e.g. adrenaline)
- increased physical activity
What are the effects of hypoglycaemia on the body?
Brain - cognitive dysfunction, blackouts, seizures, comas, psychological effects
Musculoskeletal - fails, accidents, driving accidents, fractures, dislocations
Heart - increased risk of myocardial ischaemia, cardiac arrhythmias
Circulation - inflammation, blood coagulation abnormalities, haemodynamic changes, endothelial dysfunction
What are the 5 steps for treatment of hypoglycaemia?
- Recognise symptoms
- Confirm need for treatment if possible (blood glucose <3.9 mmol/l is the alert value)
- Treat with 15g fast-acting carbohydrate to relieve symptoms
- Retest in 15 mins to ensure blood glucose >4.0 mmol/l and re-treat if needed
- Eat a long-acting carbohydrate to prevent recurrence of symptoms
What are the consequences of hypocalcaemia?
- parasthesia
- muscle spasm (hands and feet, larynx, premature labour)
- seizures
- basal ganglia calcification
- cataracts
- ECG abnormalities (long QT interval)
What is the calculation for corrected calcium?
corrected calcium= total serum calcium + 0.02*(40 - serum albumin)
What is Chvostek’s sign?
Tap over the facial nerve, look for spasm of facial muscles which indicates hypocalcaemia
What is Trosseau’s sign?
Inflate the blood pressure cuff to 20 mmHg above systolic for 5 mins.
Positive result for hypocalcaemia is carpopedal contraction of hand and wrist.
What is the difference between primary and secondary hypoparathyroidism?
Primary is decreased PTH secretion due to gland failure whereas secondary is commonly caused by surgical removal of the parathyroid gland (often accidental).
What are 2 syndromes associated with hypoparathyroidism?
- Di George
- HDR/Barakat Syndrome
What are the 4 clinical manifestations of hypoparathyroidism?
- twitching facial muscles
- muscle pains or cramps
- tiredness
- mood changes (feeling irritable, anxious, depressed)
What are the causes of hypoparathyroidism?
- surgical
- genetic
- syndromes
- radiation
- autoimmune
- infiltration
- magnesium deficiency
What is pseudohypoparathyroidism?
resistance to parathyroid hormone resulting in short stature, obesity, round facies, mild learning difficulties, subcutaneous ossification
What are the symptoms of hypercalcaemia?
- thirst
- polyuria
- nausea
- constipation
- confusion => coma
What are the chronic consequences of hypercalcemia?
- renal stones
- ECG abnormalities (short QT)
What are the 2 main causes of hypercalcaemia?
90% of cases:
- malignancy
- primary hyperparathyroidism
What are the less common causes of hypercalcaemia?
Two CHIMPANZEES
Thyroid disorders
Calcium supplements
Hyperparathyroidism
Iatrogenic
Milk-alkali syndrome
Paget’s disease
Adrenal insufficiency (Addisons)/Acromegaly
Neoplasm
Zollinger-ellison
Excessive vitamin D
Excessive vitamin A
Sarcoidosis
What is the difference between primary and secondary hyperparathyroidism?
Primary hyperparathyroidism is caused by direct alterations to the parathyroid gland e.g. cancer
Secondary is caused by physiologically elevated PTH due to reduced calcium levels
What is tertiary hyperparathyroidism?
Occurs after prolonged secondary hyperparathyroidism due to structural changes in the gland (indicated by elevated blood calcium levels)
What are the consequences of primary hyperparathyroidism?
Bones (osteitis fibrosa cystica, osteoporosis), stones (kidney), groans (confusion) + moans (constipation, acute pancreatitis)
What are the actions of parathyroid hormone?
- increased bone resorption (increased calcium levels)
- increased reabsorption of calcium and excretion of phosphate in the kidney
- increased synthesis of vitamin D (increased calcium absorption from gut)
When are changes in PTH appropriate/inappropriate?
Appropriate when maintain calcium balance.
Inappropriate when causing calcium imbalance.
What is hypercalcaemia of malignancy?
High calcium levels in the body caused by tumour secretion of parathyroid gland
Which hormones are secreted by the hypothalamus?
- GHRH & Somatostatin
- GnRH
- CRH
- TRH
- Dopamine
Which hormones are secreted by the pituitary?
- GH
- LH & FSH
- ACTH
- TSH
- Prolactin
What is the difference between Cushing’s syndrome and Cushing’s disease?
Cushing’s syndrome = Clinical manifestation of pathological hypercortisolism from any cause
Cushing’s disease = pathological hypercortisolism caused by tumour of pituitary gland
What is the typical presentation of Cushing’s syndrome?
- central obesity
- supraclavicular fullness
- facial rounding + plethora (swelling)
- violaceous striae (often across stomach)
- proximal muscle weakness
- thinning of the skin
- dorsocervical fat pads (lump at back of neck)
- ## acne
What is the pathophysiology of cushing’s syndrome?
The clinical manifestations of Cushing’s syndrome result from excess exposure of tissues to cortisol.
What are the normal effects of cortisol in the body?
- regulates the body’s stress response (maintains high alert levels produced by adrenaline and triggers glucose release for fast-release energy)
- helps control the body’s use of fats, proteins and carbohydrates
- suppresses inflammation
- regulates blood sugar (counterbalances effect of insulin by releasing stored glucose)
- regulates blood pressure (increased cortisol results in increased BP and vv.)
- helps to regulate circadian rhythm (cortisol is low in the evening and peaks in the morning before you wake up)
What are 5 complications of Cushing’s syndrome?
- diabetes mellitus
- dyslipidaemia (changes in blood lipid concentrations)
- metabolic bone disease
- hypertension
- immune suppression
What are risk factors for Cushing’s syndrome?
- adrenal adenoma
- adrenal carcinoma
- pituitary adenoma
- exogenous corticosteroid use (decreases ACTH)
What are the treatments for cushing’s syndrome?
1st line: transsphenoidal pituitary adenomectomy
- post-surgical corticosteroid or non-corticosteroid replacement therapy
What is used as a marker of an underactive thyroid?
elevated TSH levels
What are 5 disease of the pituitary?
- Benign pituitary adenoma
- Craniopharygioma (epithelial tumour)
- Trauma
- Apoplexy / Sheehans
- Sarcoid / TB
What are the potential ways that pituitary tumours cause disease?
- Pressure on local structures e.g. optic nerves
- bitemporal hemianopia
- headaches - Pressure on normal pituitary
- hypopituitarism - Functioning tumour
- Prolactinoma
- Acromegaly and gigantism
- Cushing’s disease
What are the symptoms of prolactinomas?
- galactorrhoea
- amenorrhoea
- infertility
- loss of libido
- visual field defect
What is used to treat prolactinomas?
Dopamine agonist e.g. cabergoline or bromocriptine
What thelarche?
Breast development, the first visible change of puberty, induced by estrogen
What is adrenarche?
Maturation of the adrenal gland where a specialized subset of cells arises forming the androgen-producing zona reticularis.
Results in mild advancement of bone age, axillary hair, oily skin, mild acne and body odour.
What is the incidence of precocious puberty?
1 in 5,000-10,000
90% patients female
What is precocious puberty?
Thelarche and increased growth velocity before age 8 in girls and genital development in boys before age 9.
What are the two forms of precocious puberty?
- Gonadotrophin-dependent precocious puberty (GDPP; due to premature activation of the hypothalamo-pituitary-gonadal axis)
- Gonadotrophin-independent precocious puberty (GIPP; due to autonomous secretion of sex steroids)
Define hyperthyroidism
Excess of thyroid hormones in the blood
What are the 3 mechanisms for developing hyperthyroidism?
- Overproduction of thyroid hormone
- Leakage of preformed hormone from the thyroid
- Ingestion of excess thyroid hormone
What are 6 causes of hyperthyroidism?
common
- Graves disease (75-80% of cases)
- Toxic multinodular goitre
- Toxic adenoma
less common
- congenital hyperthyroidism
- non-autoimmune hereditary thyroiditis
- subacute thyroiditis (De Quervain’s)re
Which 4 medications can cause drug-induced hyperthyroidism?
- Iodine
- Amiodarone
- Lithium (rare)
- Radiocontrast agents
What are the clinical features of hyperthyroidism?
- weight loss
- tachycardia
- hyperphagia
- anxiety
- tremor
- heat intolerance
- sweating
- diarrhoea
- lid lag + stare
- menstrual disturbance
What is Graves’ disease?
AN autoimmune condition where the immune system attacks the thyroid gland causing to become overactive.
What are the Graves’ specific signs of hyperthyroidism?
- diffuse goitre
- thyroid eye disease (infitrative)
- pretibial myxoedema
- acropathy