Endocrine Flashcards
What is the definitive management of tertiary hyperparathyroidism?
Surgery to remove the parathyroid glands
How will tertiary hyperparathyroidism manifest in blood tests?
Inappropriately high PTH levels
Increased serum calcium
Increased serum phosphate
Why does CKD cause secondary hyperparathyroidism?
In response to hypocalcemia
How does secondary hyperparathyroidsim lead to tertiary hyperparathyroidism?
Overtime gland hypertrophy causes PTH secretion to become autonomous and independent of negative feedback, leading to raised PTH and raised calcium
What is the order of hormone loss in pituitary hormone deficiency?
Growth hormone Gonadotrophins TSH ACTH Prolactin
What is the first line treatment of SIADH?
Fluid restriction
What features indicated a diagnosis of SIADH?
Euvolaemic hyponatremia
Low serum osmolality
High urine osmolality
High urine sodium
What is MEN 1 syndrome?
Mutations in the MEN1 gene cause neoplastic mutations of pituitary, parathyroid and the pancreas?
What are the symptoms of hypernatremia?
Thirst Apathy Irritability Weakness Confusion Reduced conciousness Seizures Hyperreflexia Spasticity Coma
Causes of HYPOvolemic hypernatremia?
Renal free water losis (osmotic diuresis (NG feed), loop diuretics, intrinsic renal losses)
Non-renal free water loses (excess sweating, burns, diarrhoea, fistulas)
EUvolemic hypernatremia causes?
Renal losses (Diabetes insipidus, hypodispia) Extra-renal losses (insensible, resp losses)
HYPERvolemic causes of hypernatremia?
Primary hyperalodsteronism Cushing's syndrome Hypertonic dialysis Hypertonic sodium bicarbonate Sodium chloride tablets
Main differential for diabetes insipidus?
Psychogenic polydipsia
What is the urine osmolality in DI?
Urine osmolality <300 (dilute urine)
What is the sodium status of a patient with DI?
Hypernatermic
Or Normal
Causes of cranial DI?
Impaired release of ADH
Tumours
Trauma/post-op
Cerebral vasculitits (SLE, Wegener’s_
Causes of Npehrogenic DI?
Resistance to ADH: Congenital Drugs (lithium, amphoterecin, demeclocycline) Hypokalaemia Hypercalcemia Tubulointersitial disease
How is hypernatremia treated?
Treat underlying cause
Free water
Symptoms of hyponatremia?
Decreased perception Gait disturbance Yawning Nausea Reversable ataxia Headache Apathy COnfusion seizures Coma
What is the plasma osmolality in hyponatremia?
Low
If normal or raised it is psudohyponatremia
Why does pseudohyponatremia occur?
High Lipids
Myeloma
Hyperglycemia
Uraemia
Causes of HYPOvoaemia hyponatraemia?
Renal loss
-Diuretics (thiazides)
-Osmotic diuresis (glucose, urea in recovering ATN)
Addison’s disease - mineralcortocoid deficiency
Non-renal loss
-Diarrhoea
-Vomiting
-Sweating
-Third space losses (burns, bowel obstruction pancretatitis)
At which rate should you correct hypovolaemic hyponatremia?
0.9% NaCl at 1-3ml/kg/hour
What will the urine sodium be in a patient with hypovoaemic hyponatraemia due to renal losses?
> 20mmol/L
What will the urine sodium be in a patient with hypovoaemic hyponatraemia due to non-renal losses?
<20mmol/L
Causes of Euvolaemic Hyponatremia?
Primary polydipsia (urine osmolality <100) Glucocorticoid deficiency - adrenal insufficiency, SIADH Hypothyroidism
What is SIADH
Euvolaemic hyponatraemia
Low serum osmolality
Inappropriately concentrated urine - urine osmolality >100, Na>20
Not on diuretics
DIagnosis of elimintation - normal renal, thyroid, adrenal function
How is SIADH managed?
Fluid restrict <800ml/day
PO sodium chloride
May give furosemide
Demeclocycline/tolvaptan
Causes of hypervolaemic hyponatremia?
CCF
Nephrotic syndrome
Liver cirrhosis
How is hypervolaemic hyponatremia treated?
Fluid restriction
COnsider furosemide
What is the risk of correcting hyponatraemia too quickly, and how much should be aimed to correct each day?
Central pontine/osmotic myelinosis
Aim to correct <12 mmol/L/day
How is acute hyponatremia treated (within 48 hours) if symptomatic?
Given 3% hypertonic saline IV boluses +/- furosemide
How is symptomatic chronic (48 hours or more) hyponatermia treated?
Hypertonic saline boluses only if fitting
Otherwise isotonic saline and furosemide - aim for 8mmol/L in 24 hours
How is chronic, asymptomatic hyponatermia treated
Stop offending drug
Water restriction
If dehydrated, restore volume, if overloaded - Na and water restriction and diuretics
Causes of hyperkaelmia?
CKD
K rich diet (dried fruit, potatoes, oranges, tomatoes, avacados, nuts)
Drugs
Hyperalodsteronism, Addison’s disease, Acidosis, DKA, rhabdomyolysis, tumour lysis, massive haemolysis, succinylocholine use
Rarer - hyperkalaemic periodic paralysis, Gordons syndrome
Artifcat hyperkalaemia, haemolysis, leucocoytosis, thrombocytosis
What drugs can cause hyperkalaemia?
ACEi ARBs Sprinolactone Amiloride NSAIDs Heparin LMWH CYclosporin Calcineurin inhibitors High dose trimethoprim Digoxin toxicity B-blockers
How can hyperkalemia be treated?
Low K diet
Lopp diuretic if fluid overloaded
IV calcium gluconate
IV insulin with glucose, B2 agonist nebs
Less common causes of hyperkalemia?
Hyporeninaemic Hypoaldosteronism (Type IV RTA)
Hypochloraemic acidosis in about 50%, hyperkalaemia,
typically with increased age and reduced eGFR classically
in diabetes nephropathy, acute GN (nephritis), TIN/sickle
cell, NSAIDs, CNIs, lupus nephritis
What are the symptoms of hypokalaemia?
Fatigue Constipation Proximal muscle weakness Paralysis Cardiac arrythmias Worsened glucose control in diabetics HTN
Causes of hypokalaemia?
Pseudohypokalaemia - acute leukaemia
Extra-renal losses - indadequete PO intake, gut losses (NG, vommiting, secretory diarrhoea, laxatives, VIPoma, zollinger-ellison, ileostomy , enteric fistula)
Redisribution - delerium tremens, beta agonists, insulin caffine, theophylline, alpha-blockers (doxazosin), hypokalaemic periodic paralysis
Refeeding syndrome, alkalosis, vigourous exercise,
glue sniffing
Primary hyperaldosteronism (conn’s syndrome), cushings synfrome, secondary hyperaldosteronism
Renal losses (diuretics, RTA, tubulopathies, bartters/liddles/gittlmans), liqiorice, flucocorticoids, hypomagesaemia)
What proportion of the basal bolus insulin regime should be short acting (so the peak corresponds to the glycemic load of each of the three daily meals)?
60%, across 3 doses
What proportion of the basal bolus insulin regime should be long acting?
40%
What is Felty’s syndrome?
Triad of rheumatoid arthritis, splenomegaly and neutropenia
Notable side effects of corticosteroids?
Oedema Fluid retention Hypokalemia Supine HTN Glucose intolerance
How does Conn’s syndrome present?
Metabolic alklaosis Hypokalaemia HTN Hypernatremia Patients do not present with vomiting
How is diabetes insipidus investigated (first line test)?
Water deprivation test
Patients are deprived of fluids for 8 hours or until 3% loss of their body weight is reached.
Serum osmolaity, urine volume and urine osmolality are all measured hourly.
Positive if suboptimal response in urinary concentration to dehydration (urine osmolality<700mOsm/kg)
The level of concentration in urine osmolality gives and indication of renal concentrating capacity, and thus the severity of diabetic insipidus
Why do patients with Addisons disease not always have hyponatremia?
Although aldosterone normally enhances sodium reabsorption, other sodium retaining mechanisms such as the renin-angiotensin-aldosterone system are able to compensate to an extent
COmplication of severe hyponatremia?
brain herniation
What type of hyponatermia does SIADH cause?
Euvolemic hyponatremia
Urine sodium is above 40mmol/L and serum osmolality is above 100mosmol/L
How is acute severe hypercalcemia (>3.5) treated initially?
IV 0.9% saline 4L/24 hours
Agressive fluid rehydration will improve kidney function and help excess calcium be excreted
What is the combination of raised PTH, raided calcium and decreased phosphate charcteristic?
Primary hyperparathyroidism (overproduction of PTH by the parathyroid glands)
Most common causes of pseudohyponatremia?
Secondary to hyperlipidemia
Paraproteinaemia as seen in multiple myeloma
High blood glucose levels and use of mannitol or glycine
How to confirm a diagnosis of pseudohyponatraemia?
Measure serum osmolality level
Level of 275 mOsm/kg + supports the diagnosis
What blood test abnormalities can haemolysis of a sample before laboratory processing cause?
Pseudohyperkalemia due to potassium from inside red cells released into the serum
Potassium levels are significantly higher in red cells than in the serum hence significant alteration of true potassium level
What can cause pseudohyperkalemia?
Prolonged torniquet time during venepuncture (lactic acid production from temp ischema)
Haemolysis of blood sample before the lab
What is the first-line investigation for Addison’s disease
Morning serum cortisol - between 8 and 9 am when cortisol levels peak
Do not wait for result in an addisonian crisis, give IV hydrocortisone straight away
What paroneoplastic syndrome can cause SIADH?
Small cell lung cancer
What is the gold standard diagnostic test for a phaeochromocytoma?
Urine metanephrines
Plasma metanephrines
How is carcinoid syndrome diagnosed?
Urinary 5-HIAA excertion in a 24 urinary collection
What is Cushing’s Syndrome?
Signs and symptoms developing after prolonged abnormal elevation of cortisol
What is Cushing’s disease?
Subtype of cushing’s syndrome which occurs when a pituitary tumour secretes excessive ACTH.
Features of Cushing’s syndrome features?
ROUND IN THE MIDDLE WITH THIN LIMBS Round 'moon' face Central obesity Abdnominal striate Buffalo Hump (fat pad on upper back) Proximal limb muscle wasting HTN Cardiac hypertrophy Hyperglycaemia (Type 2 Diabetes) Depression Insomina Osteoporosis Easy bruising and poor skin
Causes of Cushing’s Syndrome?
Exogenous steroids - long term high dose steroid medication
Cushing’s DIsease (a pituitary adenoma releasing excessive ACTH)
Adrenal Adenoma
Paraneoplastic Cushing’s
What is Paraneoplastic Cushing’s?
Ectopic ACTH
Excess ACTH relased from a cancer (not of the pituitary) and stimulates cortisol release.
What is the most common cause of Paraneoplastic Cushing’s?
Small cell lung cancer
What is the gold standard investigation for Cushing’s disease?
Dexamethasone suppression test
How does the dexamethasone supression test work?
Initial low dose test - if normal, excludes Cushing’s syndrome
Abnormal test - perform high dose test performed
Dose of dexamethasone given at night time.
Cortisol and ACTH is measured in the morning (9AM)
Goal is to find out if dexamethasone supresses their normal morning cortisol spike.
Low dose dexamethasone suppression test dosage?
1mg
What is the dose for high dose dexamethasone suppression test?
8mg
What is a normal response to the low dose dexamethasone supression test (1mg)?
Dexamethasone supresses the release of cortisol be effecting negative feedback on the hypothalamus and pituitary.
What response will be shown in cushing’s disease in the high dose dexamethasone supression test?
Pituitary still show some response to the negative feeback and 8mg is enough to suppress the cortisol (but 1mg in the low dose test is not hence abnormal response there)
What is the response to the high dose dexamethasone supression test in an adrenal adenoma and why?
Cortisol not supressed as cortisol production is happening independent of the pituitary.
ACTH is supressed due to negative feedback on hypothalamus and pituitary gland
What is the response to the high dose dexamethasone suppression test where ectopic ACTH is being produced?
Neither cortisol of ACTH are suppressed because the ACTH production is independent of the hypothalamus or pituitary gland.
Why is 24 hour urinary free cortisol not the first line investigation for Cushing’s syndrome?
Can diagnose cushings, but
Cumbersome to carry out
And no indication of underlying cause
What investigations unrelated directly to cortisol and ACTH may be carried out when investigating Cushing’s
FBC: raised WCC Electrolytes: in an adrenal carcinoma, if alodsterone is also secreted there may be hypokalemia MRI brain for pituitary adenoma Chest CT - SCLC Abdonminal CT - adrenal tumor
How is Cushing’s syndrome treated?
Transpehenoidal removal of pituitary adeoma
Surgical removal of adrenal tumour
Surgical removal of tumour producting ectopic ACTH
If the above are not possible: removal of adrenal glands and give the patient replacement steroid hormones for life
What is Addison’s disease?
Primary adrenal insufficiency, usually caused by an autoimmune process damaging the adrenal glands which leads them to not produce sufficient cortisol or aldosterone.
What is secondary adrenal insufficiency?
Result of inadequate ACTH stimulating the adrenal glands resulting in low cortisol release.
This is a result of loss or damage tk the pituitary gland:
Surgery
Pituitary tumour
Lack of blood to pituitary gland
Radiotherapy
Sheenans syndrome
What causes Sheenans syndrome?
Loss of blood during child birth causes necrosis of the pituitary gland
What is tertiary adrenal gland sufficiency?
Result of inadequate CRH release by the hypothalamus
Usually the result of >3 week course of steroids causing hypothalamic suppression, when the exogenous steroids are withdrawn the hypothalamus does not respond adequately and endogenous steroids are not produced
Why must high dose long term steroids be tapered down slowly?
Allow adrenal axis to regain normal function
Describe how the adrenal axis leads to steroid production?
CRH from the hypothalamus acts on anterior pituitary gland
ACTH from the AP acts on the adrenal glands
Adrenal glands release cortisol which has a negative feedback on the hypothalamus and AP
Signs and symptoms of adrenal insufficiency?
Fatigue Nausea Cramps Abdominal pain Reduced libido Hyperpigmentation Hypotension
Why is early morning cortisol not the investigation of choice for Adrenal Insufficiency?
Often falsely normal
What viruses may trigger T1DM?
Coxsakie B virus
Enterovirus
Pathophysiology of T!DM?
Pancreatic B cell loss in the Islets of Langerhans in the pancrea due to T cell mediated destruction
No production of insulin (anabolic hormone)
Cells of the body can not take up glucose, muclse and liver cells don’t take up glucose and store it as glycogen
Cells cannot take up glucose
Blood glucose rises - hyperglycemia
What blood sugar does the body aim to maintain?
4.4-6.1 mmol/L
What is glucagon?
Catabolic homrone that increases blood sugar levels
Produced by alpha cells in the Islets of Langerhans in the pancrea
Causes liver to break down glycogen stores into glucose - glycoenolysis
Causes liver to convert proteins and fats in to glucose - gluconeogensis
What is ketogenesis and when does it occur?
Production of ketones - water soluble acids that can be used as fuel and are able to cross the blood brain barrier
Insufficient supply of glucose and glycogens stores are exchausted (prolonged fasting state)
Liver converts fatty acids to ketones
Normal in fasting conditions or on a very low carbohydrate, high fat diet
Presentation of DM?
Hyperglycemia triad - polyuria, polydipsiya, weight loss
Secondary enuresis
Reccurent infections
TYPE 1 - DKA
Investigating suspected diabtetes?
Baseline bloods including FBC, renal profile (U&E) and a formal laboratory glucose
Blood cultures should be performed in patients with suspected infection (i.e. with fever)
HbA1c can be used to get a picture of the blood sugar over the previous 3 months. This gives an idea of how long they have been diabetic prior to presenting.
Thyroid function tests and thyroid peroxidase antibodies (TPO) to test for associated autoimmune thyroid disease
Tissue transglutaminase (anti-TTG) antibodies for associated coeliac disease
Insulin antibodies, anti-GAD antibodies and islet cell antibodies to test for antibodies associated with destruction of the pancreas and the development of type 1 diabetes
What HbA1c indicates diabetes?
48 mmol/mol or higher
Situations where HbA1c must not be used as the sole test to diagnose diabetes?
Symptomatic children and young people <19 years
Symptoms suggesting T1DM
Short duration (<2 months)
Patients at high risk of diabetes who are acutely ill
Taking medication that may cause rapid glucose increase (steroids, antipsychotics)
Acute pancreatic damage/pancreatic surgery
In pregnancy
Presence of genetic, haematologic and illness related factors that influence HbA1c and its measurement
NOTE repeat readings same lab within 2 weeks if asymtomatic
Patients with what HbA1c should be monitored annually?
42-47 mmol/mol
Long term management of T1DM?
Subcutaneous insulin regimes
Monitoring dietary carbohydrates
Monitoring blood sugar levels on waking, before each meal and before bed
Monitoring for and managing complications
Describe a basal bolus insulin regime
Basal - long acting insulin such as Lantus - gives a constant background of insulin throughout that day. Typically given OD at night
Bolus - short acting insulin such as Actrapid - given three times a day before meals - also injected as per the number of carbohydrates consumed every time the patient has a snack.
What are the two types of insulin pump?
Tethered pump - devices with replaceable infusion sets and insulin
Patch pump - sits directly on the skin, controlled by a seperate remote. Disposable
Both constantly insfuse insuling via a cannula, site changed every 2-3 days to prevent lipodystrophy
Advantages of insulin pump?
Better blood sugar control
More flexability with eating
Less injections
Disadvantages of an insulin pump?
Difficulties learning to use it
Having it attatched at all times
Blockages in the infusion set
Small risk of infection
Short term complications of T1DM?
Hypogylcemia
Hyperglycemia and DKA
What causes hypoglycemia?
Too much insulin Not enough carbohydrates Not processing carbohydrates correctly - malabsorbtion, diarrhoea, vomitting, sepsis Hypothyroidism Glycogen stoarge disorders Growth hormone deficicency Liver cirrhosis Alcohol Fatty acid oxidation defects such as MCADD
Symptoms of hypoglycemia?
Hunger Tremor Sweating irritablility Dizziness Pallor Reduced conciousness Coma Death
How should hypoglycemia be treated?
No impairment of consciousness - rapid acting glucose such as lucozade and slower acting carbohydrates such as biscuits or toast to maintain the blood sugar level when the rapid acting glucose is used up
Impairment of conciousness - IV dextrose (10% - 2mg/kg bolus followed by 5mg/kg/hour infusion) and intramuscular gulcagon
What is nocturnal hypoglycemia and how can it be treated?
Hypoglycemia overnight
Child may be sweaty overnight
Morning blood glucose levels may be raised
Diagnosis made by continuous glucose monitoring
Alter bolus insulin regime and give snacks at bedtime
Why do patients with DM experience complications?
Chronic exposure to hyperglycemia causes
1. Damage to the endothelial cells of blood vessels
This leads to leaky, malfunctioning vessels that are unable to regenerate
2. Supression of the immune system and creates an optimal environement for microorganisms to thrive
Macrovascular complications of diabetes?
Coronary artery disease
Peripheral ischemia (poor healing, diabetic foot)
Stroke
HTN
Microvascular complications of diabetes?
Urinary tract infections
Pneumonia
Skin and soft tissue infections -particularly in the feet
Fungal infections - particularly oral and vaginal candidiasis
What is HbA1c considered to reflect?
Count of glycated Hb with is how much glucose is attatched to the haemoglobin molecules inside the RBC
Average blood glucose level over the last 3 months (RBC lifespan around 3-4 monthhs)
How can blood sugar be monitored?
HbA1c - 3 to 6 months
CBG with glucose meter - daily
Flash Glucose monitoring (FreeStyle Libre) - daily
How does the FreeStyle Libre machine work?
This uses a sensor on the skin that measures the glucose level of the interstitial fluid in the subcutaneous tissue
There is a 5 min lag behind blood glucose
Sensor records the glucose readings at short intervals
Swipe over reader with a sensor - this needs replacing every 2 weeks
Pathophysiology of DKA?
Patient not producing adequete insulin and not injecting adequete insulin to compensate for this. Not enough insulin to use and process glucose. Cells of the body interperit this as a state of starvation and initiates the process of ketogenesis
Glucose increases, ketones increase
Initially the kidneys produce bicarbonate to counteract the ketone acids in the blood and maintain a normal pH
Over time the ketone acids use up the bicarbonate and the blood becomes acidic - ketoacidosis
Why does DKA cause polydipsia and polyuria?
Hyperglycemia overwhelms the kidenys and glucose starts being filtered into the urine
The glucose in the urine draws water out with it (osmotic diuresis). This leads to polyuria, which leads to severe dehydration which stimulates the thirst centre in the hypothalamus, hence polydipsia.
Why can DKA cause arrhythmia?
Insulin normally drive potassium into the cells
Serum potassium and be high or normal as the kidneys continue to balance blood potassium excreted in the urine - however total body potassium is low
Without treatment patients can develop severe hypokalaemia very quickly
This can lead to fatal arrythmias
How does DKA presents?
Hyperglycaemia Dehydration Ketosis Metabolic acidosis (with a low bicarbonate) Potassium imbalance Polyuria and polydipsia N&V Acetone smell to their breath Dehdration and subsequent hypotension Altered conciousness Symptoms of an underlying trigger (sepsis)
Most dangerous aspects of DKA?
Dehydration
Potassium imbalance
Acidosis
Diagnostic criteria for DKA?
Hyperglycemia (CBG > 11 mmol/L)
Ketosis (blood ketones > 3 mmol/l)
Acidosis (ie. pH < 7.3)
How is DKA treated?
Fluids
Insulin (infusion, e.g. actrapid at 0.1 unit/kg/hour)
Glucose - closely monitor, add a dextrose infusion if below a certain level (e.g. 14 mmol/l)
Potassium - closely monitor serum potassium (e.g. 4 hourly) and correct as required - no more than 10 mmol per hour
Infection - treat underlying triggers such as infection
Chart - fluid balance
Ketones - monitor blood ketones (or bicarbonate if ketone monitoring)
Establish the patient on their normal subcut insulin regime prior to stopping the insulin fluid infusion
Non-modifiable risk factors?
Older age
Ethnicity (black, chinese, south asian)
Family history
Modifiable risk factors for type 2 DM?
Obesity
Sedentary lifestyles
High carbohydrate (particularly refined carbohydrate) diet
How might T2DM present?
Fatigue Polydipsia and polyuria (thirsty and urinating a lot) Unintentional weight loss Opportunistic infections Slow healing Glucose in urine (on dipstick)
Usually in patients with risk factors
How is the OGTT performed?
Take baseline fasting plasma glucose result
Give 75g glucose drink
Measure plasma glucose 2 hours later
How can pre-diabetes be diagnosed?
HbA1c 42-47 mmol/mol
Impaired fasting glucose 6.1-6.9 mmol/mol
Impaired glucose tolerance - plasma glucose at 2 hours - 7.8 - 11.1 mmol/l on an OGTT
How can diabetes be diagnosed?
HbA1c > 48 mmol/mol
Random Glucose > 11 mmol/l
Fasting Glucose > 7 mmol/l
OGTT 2 hour result > 11 mmol/l
Management of T2DM?
Dietary Modification
Vegetables and oily fish
Typical advice is low glycaemic, high fibre diet
A low carbohydrate may in fact be more effective in treating and preventing diabetes but is not yet mainstream advice
Optimise Other Risk Factors
Exercise and weight loss
Stop smoking
Optimise treatment for other illnesses, for example hypertension, hyperlipidaemia and cardiovascular disease
Monitoring for Complications
Diabetic retinopathy
Kidney disease
Diabetic foot
What is the first line medical management of T2DM?
Metformin titrated from initially 500mg once daily as tolerated
What s the second line medical management of T2DM?
Metformin +
sulfonylurea/pioglitazone/DPP-4 inhibitor/SGLT-2 inhibitor
What is the third line medical management of T2DM?
Metformin + 2 of:
sulfonylurea/pioglitazone/DPP-4 inhibitor/SGLT-2 inhibitor
OR
Metformin+insulin