Kidney failure happens when kidneys cannot properly function. Kidney failure has adverse effects on waste removal and blood filtering which lead to health problems. There are different treatment options for kidney failure. Medical diagnoses can be made by testing the products found in urine.

Kidney failure

Kidney failure/renal failure happens when the kidneys cannot function properly and normal processes are prevented. The glomerular filtration rate (GFR) is a good indicator of kidney failure.

The GFR measures how quickly blood is filtered from the glomerulus to the Bowman's capsule. If the GFR drops below the normal level it shows that the kidneys are not functioning properly.

Kidney infections

Kidney infections cause inflammation of the kidneys which leads to cellular damage preventing proper filtration. The Bowman's capsule and reabsorption are heavily affected by kidney infections. Kidney infections can induce kidney failure.

High blood pressure

High blood pressure damages the glomeruli. Pressure in the glomerulus is naturally very high so when blood pressure rises then capillaries in the glomerulus can rupture. Larger molecules like proteins are now found in the filtrate and normal kidney function is affected. High blood pressure can trigger kidney failure.

Consequences

Adverse events are induced following kidney failure. Waste products like urea that are normally removed by the kidneys accumulate in the blood. High concentrations of urea in the blood induce weight loss and vomiting.

Excess water in the blood is not properly removed causing water to accumulate in the legs, face and abdomen. This causes large amounts of swelling. Electrolyte levels are also controlled by the kidneys. This makes the blood more acidic and bones become brittle.

Treatment

Renal dialysis

Renal dialysis involves mechanical removal of waste products from the blood when kidneys cannot achieve this themselves. There are two forms of dialysis called haemodialysis and peritoneal dialysis.

Haemodialysis

Blood is removed from a patient into the machine, the blood is passed along a partially permeable membrane with dialysis fluid on the other side of the membrane. Waste products and excess water and ions are removed from the blood as they diffuse through the membrane into the fluid. Blood cells and larger molecules like proteins cannot pass through the membrane. This treatment is carried out around two times a week.

Peritoneal dialysis

Dialysis fluid is put in a tube which goes into the patients abdominal cavity. Waste products in the patients blood diffuse across the peritoneum and into the dialysis fluid. The peritoneum is the chest cavity membrane. This method has a risk of infection and must be repeated daily.

Transplantation

A kidney from a donor can be transplanted into a patient suffering from severe kidney failure. Transplants are preferable to dialysis because they are a long term treatment option and patients do not have to visit hospital multiple times a week.

Kidneys must be transplanted from someone with exactly the same blood type as the patient. This does not prevent an immune response being generated because the immune system will reject the transplanted kidney and therefore patients must take immunosuppressant drugs.

Diagnosis through urine

Pregnancy

Urine is essentially filtered blood. Therefore, you can discover what is in a persons blood by testing their urine. Human chorionic gonadotropin (hCG) is a hormone only found in the urine of pregnant women.

On a test strip monoclonal antibodies for hCG are bound to a blue coloured bead. When urine is applied to the test strip any hCG in the urine will bind to the antibodies and move up the strip with the urine. The test strip also has a line of antibodies for hCG stuck in place.

If there is hCG present in urine then it will interact with the stuck antibodies whilst still interacting with the coloured bead. Therefore, a strip of coloured beads will be formed and the test will present a solid blue line which indicates a person is pregnant.

Biology; Excretion; KS5 Year 12; Kidney failure and detecting chemicals — A. a pregnancy test, B. a positive pregnancy test, C. a negative pregnancy test

1.	The part of the stick you urinate on.
2	Antibodies specific to hCG with blue beads attached.
3.	The test strip (the part that turns blue if you're pregnant) .
4.	Antibodies are stuck down. The test strip has more antibodies specific to hCG stuck onto it.
5.	Hormone (hCG) bound to antibody that is attached to a bead.
6.	The beads are carried in a flow of liquid towards the test strip.
7.	If you're pregnant, the hormone binds to the antibodies with the blue beads attached and the urine moves up the stick carrying the hormone and the beads. The beads and hormones bind to the antibodies on the test strip. The blue beads get stuck on the strip turning it blue.
8.	If you're not pregnant, the urine still moves the blue beads to the test strip, but as there is no hormone, nothing sticks to the test strip so it doesn't go blue.

Steroids

Anabolic steroids are used by people to build muscle. It is deemed an unfair advantage when athletes use anabolic steroids. Therefore, they are regularly tested for steroid use.

A urine sample is vaporised and moved through a column containing a polymer. Varying substances have different sizes, therefore, they move through the column at different speeds. A mass spectrometer is utilised to convert the separated substances into ions and subsequently differentiates them using charge and mass.

The results are analysed by a computer. Different steroids have unique mass spectrometer patterns and the results are cross-analysed against steroid profiles to determine if a person is using steroids.

Recreational drugs

Recreational drugs are removed from the body through urine. Drug tests follow the same principal as pregnancy tests utilising antibodies for specific compounds like cannabis, ecstasy and cocaine.

Learn with Basics

Length:

Unit 1

Homeostasis and blood glucose

Unit 2

The urinary system

Jump Ahead

Optional

Unit 3