Treating kidney failure
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Objectives of lesson
• Describe the symptoms and causes of kidney failure
• Explain methods of diagnosing kidney failure
• Describe treatments for kidney failure and the pros and
cons for each treatment
• Discuss how organ donations could be increased
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Kidney failure
• When kidneys start to fail, toxins such as urea start to
accumulate in the body and fluid will accumulate in
tissues.
• What symptoms would you expect a patient to notice?
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Kidney failure
• Oedema – swelling due to accumulation of fluid in
tissues
• Urine may contain blood, protein and be cloudy
• Anaemia and tiredness– as kidneys stop producing
erythropoetin
• Rashes, nausea – due to build up of toxins
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Kidney failure
• http://www.lifeoptions.org/kidneyinfo/ckdinfo.php?page=4
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Causes of acute renal failure
• A serious illness or operation especially if severe
infection occurs.
• Loss of large amount of blood or tissue fluid
• A blockage preventing drainage of urine from the kidney
eg a kidney stone
• Also – can be caused by side effect of some medications
and by a bacterial infection of the kidney
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Causes of chronic renal failure
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Complication of diabetes mellitus
Uncontrolled high blood pressure
Inflammation of kidney tissue
As a result of inherited diseases of the kidney such as
polycystic kidney disease.
Diagnosing kidney disease
• Look for symptoms such as oedema and cloudy or
bloody urine
• Ultrasound and CT scans to look for blockages
• Analyse urine samples for blood cells and protein.
– Q: Why should these not be present in urine?
© OCR 2016
Diagnosing kidney disease
• Look for symptoms such as oedema and cloudy or
bloody urine
• Ultrasound and CT scans to look for blockages
• Analyse urine samples for blood cells and protein.
– Q: Why should these not be present in urine?
– A: They are too big to pass from the blood, through
the walls of the capillaries in the glomerulus and into
the Bowman’s capsule
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Analysing blood samples
• Blood can be analysed for a waste substance called
creatinine which increases as kidney disease progresses
– failing kidneys do not remove wastes from the blood.
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Glomerular filtration rate (GFR)
• This is the volume of fluid that is filtered out of the blood per
minute and can also be used to measure kidney function. A
substance such as inulin* can be injected into the blood
stream and its removal rate measured, or the removal rate of
wastes such as creatinine can be measured.
• The lower the GFR, the less effective kidney function.
*yes, inulin, NOT insulin! Inulin is a polysaccharide that passes
easily into the urine during filtration in the healthy glomeruli and is
not reabsorbed later, so the amount in urine is a very good indicator
of how well that part of the kidney is working
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Glomerular filtration rate (GFR)
• Q: Why must the salt intake of someone with kidney
failure be carefully controlled?
• A: Sodium chloride would build up in the blood altering
the water potential of blood plasma leading to retention
of water (oedema), excessive thirst and eventually
cardiac arrest.
© OCR 2016
Diagnosing kidney failure
• In pairs, imagine one of you is the doctor and one is the
patient with kidneys that are beginning to fail.
• As the doctor, what questions could you ask and what
simple tests could you carry out to determine whether
the patient has kidney problems?
• As the patient, what symptoms should you describe?
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Diagnosing kidney failure
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Test urine for protein
Look for oedema
Measure blood pressure
Ask about feeling ill or tired
Excessive thirst?
Treating Kidney Failure
• Three possible treatments:– Haemodialysis
– Peritoneal dialysis
– Kidney transplant
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Haemodialysis
• This removes waste products from the blood by passing
it out of the body, through a filtering system (dialyser)
and returning it, cleaned, to the body.
• The blood flows through tubes made of a selectively
permeable membrane that allows the waste products
(which are much smaller than blood cells) to pass out
through it.
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Haemodialysis
• In dialysis, how are substances transported from the
patient’s blood to the dialysis fluid?
• Diffusion and osmosis
• How could you avoid useful substances being removed
from the blood?
• Same concentration of substance in dialysis fluid as in
blood
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Haemodialysis
• Why should the temperature and the water potential of
the dialysis fluid be the same as that of the blood?
• To prevent cooling or warming in patient and to prevent
dehydration or over-hydration of the patient
• Why is heparin added to the blood?
• To prevent clotting of blood in dialysis machine
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Haemodialysis
• In the animation
http://www.kidneypatientguide.org.uk/HDanim.php
the blood is shown being pumped in at the top and out at the
bottom of the dialyser diagram. The dialysate is pumped
through the machine in the opposite direction (in at bottom in
the diagram, out at the top).
Why do you think it is designed like this?
Can you see a link to one of the gas exchange topics earlier
in the course?
© OCR 2016
Haemodialysis
• In the animation
http://www.kidneypatientguide.org.uk/HDanim.php
the blood is shown being pumped in at the top and out at the
bottom of the dialyser diagram. The dialysate is pumped
through the machine in the opposite direction (in at bottom in
the diagram, out at the top).
Why do you think it is designed like this?
Can you see a link to one of the gas exchange topics earlier
in the course?
• Hint: It’s an example of a ‘countercurrent’
© OCR 2016
Peritoneal dialysis
• Dialysis fluid is placed around the membrane lining the
intestine (peritoneal membrane) and toxins and excess
water diffuse out of the blood and into the dialysis fluid,
which is regularly changed.
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Peritoneal dialysis
• http://www.kidneypatientguide.org.uk/site/pdanim.php
© OCR 2016
Kidney transplant
• http://www.visibleproductions.com/index.php?page=asse
t_detail&asset_id=vpl_0485_001
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Kidney transplantation
• Can you think of any advantages and disadvantages of
transplantation compared with dialysis?
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Discussion
• How would you try to increase the availability of kidneys
for donation?
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Objectives of lesson
• Describe the symptoms and causes of kidney failure
• Explain methods of diagnosing kidney failure
• Describe treatments for kidney failure and the pros and
cons for each treatment
• Discuss how organ donations could be increased
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