Urea and Electrolytes Flashcards
Explain how we end up with urea within the body.
Eat protein, broken down by proteases, to create amino acids. Ammonia is a by product of amino acid metabolism (amino groups/nitrogen removed to create nucleic acids) and is toxic to the body. Ammonia is converted to urea by the liver and this is then transported in the bloodstream to the kidneys for excretion.
This is why urea is a good indication of how well our kidneys are wokring.
Other than kidneys, when else can urea be elevated ?
GI bleed
If there is an upper GI bleed you will get a raised urea without a raise in creatinine as you are digesting a large protein load and therefore urea is raised due to creation of urea rather than reduced excretion.
What is the components of sodium?
Regulates extracellular volume including plasma volume
Large proportion extracellular
Regulates fluid balance
Excreted in urine, faeces and sweat
What is the components of potassium
PotassiumRegulates intracellular fluid volume
Large proportion intracellular
Excreted in urine, faeces and sweat
What hormone from the adrenal gland may influence how much potassium we absorb ?
Aldosterone
What is calcium important for ?
Vasoconstriction/dilation
Muscle function
Nerve transmission
Intracellular signalling
Stored in bone/teeth- supports function
What diuretic wont effect our potassium
Spiralactone
What is Rhabdomyelalysis
Rhabdomyolysis (often called rhabdo) is a serious medical condition that can be fatal or result in permanent disability. Rhabdo occurs when damaged muscle tissue releases its proteins and electrolytes into the blood. These substances can damage the heart and kidneys and cause permanent disability or even death.
Hyperkalemia is further aggravated by metabolic acidosis induced by the release of various organic acids (e.g., lactic acid, uric acid) from the disrupted muscle cells
What other test would you want to do with hyperkalemia?
ECG
Significant hyperkalemia changes will be.
Widening of the QRS Complex and a peaked T wave.
What is more dangerous, hypokalemia or hyperkalemia ?
Hypokalaemia leads to muscle weakness & paralysis – can give rise to heart block
However immediate life threat is with hyperkalaemia
Non renal causes of hyperkalemia ?
Artefact
Improper collection of sample
Tissue damage
Redistribution cells & ECF:
Acidosis
Hypoxia
Why does acidosis cause hyerkalemia ?
Acidosis causes potassium to move from cells to extracellular fluid (plasma) in exchange for hydrogen ions
What renal causes cause hyperkalaemia ?
AKI
CKD
Drugs:
ACE inhibitors
Diuretics
Amiloride
Spironolactone
Why can low sodium cause hyperkalemia ?
eg from giving diuretics
The decrease in the distal delivery of sodium will result in less reabsorption of sodium and consequent decreased potassium secretion in the cortical collecting tubule, thereby resulting in hyperkalemia.
What do you have to be careful with when giving IV potassium
DONT GIVE IT TOO QUICK
DOSE OF HYPERKALEMIA TREATMENT
Protect the HEART!
Calcium gluconate-10 10 10
10ml
10%
10 mins
Push K+ into cells
Insulin Dextrose
50ml 50% dextrose
10 unit actrapid
Salbutamol
Remove the K+ from the body!
Dialysis/resonium
++ CORECT UNDERYLYING CAUSE
PA in a GP clinic
28 year old male
Referred following a well-man clinic at work
“Hypertensive”
BP 140/90 mmHg
No oedema
What investigations?
What expecting?
What will you do with the results?
U+E
ECG
They have a metabolic alkalosis + an increased sodium
Water and sodium follow each other so increased circulating blood volume which has increased the blood pressure.
DIAGNOSIS - CONNS SYNDROME
what does alkalosis do to potassium
The patient is alkalosis eg bicarbonate of 35, so more potassium going into the intracellular space and therefore low potassium.
What can cause hypokalemia
Reduced intake
Increase loss
Drugs:
Diuretics
Steroids
CONNS
Cushing’s syndrome
Hypercalcaemia
Hypomagnesaemia
How does aldosterone effect the neprhons ?
Aldosterone causes sodium to be absorbed and potassium to be excreted into the lumen by principal cells.
What is conns syndrome ?
Conn’s syndrome is a hormonal condition in which one or both adrenal glands produce more of the hormone aldosterone than normal.
Therefore more potassium is excreted.
Why are you likely to have hypomagnesemia with hypokalemia?
Magnesium tends to follow potassium.
Explain conns syndrome
Conn’s- high aldosterone- more K excreted in urine (hypokalaemia), Na (Hypernatraemia) and H20 retention (hypertension).
CASE STUDY
Interpretation:
What is abnormal?
What is the most abnormal?
Any patterns?
On diuretics
Diuretic induced hypokalmeia
Sodium is gonna follow the water
What should urine not be less than?
0.5ml/ kg/ hour
PA in Gen Surgery
67 year old male
Hemicolectomy CA colon
6th post-op day - urine output 300ml
Interpretation:
What is abnormal?
What is the most abnormal?
Any patterns?
A pre-renal issue because he has had surgery, there is likely to be a bleed, trauma to the cell, and cell death, leading to more breakdown of protein.
What are some causes of uraemia ?
What are pre-renal causes of ureaemia ?
Due to Increase protein break down
Major trauma
Infection
Large GI bleed
Fluid depletion
Shock
What are some renal causes of uraemia ?
Glomerular dysfunction
Prolonged pre-renal cause
Infection
Auto immune
Toxins
Genetic
What are post renal causes of uraemia ?
Due to obstruction
Renal tract obstruction
Ureteric stricture
CA bladder
BPH
How would you treat pre-renal failure?
STOP nephrotoxics
Rehydrate
Strict fluid balance
Catheter
? KUB USS – consult local protocol
CASE STUDY
PA in a GP surgery
53 year old female
3/12 lower back pain
PMH: L Mastectomy & RT 10 yr. ago for breast carcinoma
No neurological abnormalities
Healed scar
Minimal L upper limb oedema
CVS & Respiratory exam NAD
What tests would you like?
? linked to breast cancer
order a u+e, ALP, calcium
Causes of hypercalcemia
- Bony mets
Stones
renal
Bones
Bone pain
Groans
Abdominal pain (constipation)
Moans (psychiatric disturbance)
Fatigue, depression, confusion
Which specific part of the adrenal glands is aldosterone secreted from ?
zona glomerulosa cells of the adrenal cortex
