Can occur because:
- diabetes mellitus (both type 1 and type 2 sugar diabetes)
Once kidneys fail body unable to remove excess water, urea and salts.
Unable to regulate levels of water and salts.
This can lead to death.
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- Most common treatment
- Removes wastes, excess fluid and salt from blood by passing over a dialysis membrane
- Dialysis membrane is a partially permeable membrane
- Allows exchange of substances between blood and dialysis fluid
- Fluid contains correct concentrations of salts etc.
- Excess substances can diffuse across membrane into dialysis fluid.
- Too low concentrations causes substances to diffuse from dialysis fluid into blood
- Must be combined with carefully monitored diet.
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- Blood from a vein is passed into a machine containing artificial dialysis membrane
- Heparin is added to avoid clotting
- Any bubbles are removed before blood returns to body
- Usually performed at a clinic 3 times a week for several hours at each session
- Some patients learn to carry it out at home.
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Peritoneal Dialysis (PD)
- The filter is the body's own abdominal membrane (peritoneum)
- A surgeon implants a permanent tube in abdomen
- Dialysis solution is poured through tube and fills space between abdominal wall and organs
- After several hours solution is drained from abdomen.
- PD is usually performed in several consecutive sessions daily
- At home or work
- The patient can walk around while having dialysis
- Ambulatory PD
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- Old kidneys left in place unless likely to cause infection or are cancerous
- Donor kidney can be from a living relative or from someone who has died
- Major Surgery
- While patient is under anaesthesia, surgeon implants nerw organ into lower abdomen
- Then attaches it to blood supply and bladder
- Many patients feel much better immediately after transplant
- Best life extending treatment for kidney failure
- Patient's immune system will regonise new organ as foreign object
- Patients must be given immunosuppressant drugs to prevent rejection
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Advantages of kidney transplant
- Freedom from time consuming dialysis
- Diet is less limited
- Feel better physically
- Better quality of life - able to travel etc.
- No longer see self as chronically ill
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Disadvantages of kidney transplant
- Need immunosuppressants for life of kidney
- Need major surgery under general anaesthetic
- Risks of surgery - infection, bleeding, damage to surrounding organs
- Frequent checks for signs of organ rejection
- Side effects - antirejection medicines cause fluid retention and high blood pressure. Immunosuppressants increase susceptibilty to infections
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Testing urine samples
- Substances with Mr of 69000 or less can enter nephron
- And metabolic product or substance in blood can pass into urine, as long as it is small enough
- If these substances are not reabsorbed they can be detected in urine.
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- Once implanted in uterine lining, embryo secretes hormone human chorionic gonadotrophin (hCG)
- hCG is a small glycoprotein with Mr of 36700
- Can be found in urine as early as 6 days after conception
- Pregnancy tests are manufactured with monoclonal antibodies
- Only binds to hCG, no other hormones
- When woman takes pregnancy test she soaks portion of strip in urine
- Any hCG attaches to an anitbody that is attached with a blue bead
- hCG anitbody complex moves up strip until sticks to band of immobilised antibodies
- As a result all anitbodies carring a blue bead and attached to hCG are held in place forming a blue line
- There is always a control blue line for comparison, second line indicates pregnancy
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Testing for anabolic steroids
- Anabolic steroids increase protein synthesis within cells
- This results in build up of cell tissue, especially in muscles
- Non medical uses are controversial as can give advantage in competitive sports and have dangerous side effects
- Use of anabolic steroids is banned by all major sporting bodies
- Have a half life of about 16 hours and remain in blood for many days
- Relatively small molecules and enter nephron easily
- Testing involves analysing a urine sample in a lab using gas chromatography or mass spectrometry
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- The sample is vaporised in the presense of a gaseous solvent
- Passed down a long tube lined by an absorption agent
- Each substance dissolves differently in the gas and stays there for a unique specific retention time
- Eventually the substance comes out of the gas and is absorbed onto the lining.
- Then analysed to produce a chromotogram
- Standard samples of drugs, as well as urine samples are run so that drugs can be identified and quanitfied in the chromotograms.
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