Kidney filters out waste products from blood stream. Normally 200 litres of water are filtered through the kidney daily and only about 2 litres are passed as urine.

Usually, there are two kidneys in each one of us. They are bean shaped and weigh about 150gms and are 12 cm x 5 cms in size. They are located in the middle of the back, just below the rib cage. Each kidney is made up of small, complex units called nephrons. The two kidneys contain about two million nephrons. The nephrons work continuously to filter out waste products from the blood stream, all of which come from the food that one eats and the fluid that one drinks. The kidneys also regulates the concentration of most of the constituents of body fluids.

They also retain certain substances that are needed by the body. In addition, the kidneys stimulate the body to produce red blood cells, regulate blood pressure, keep bones healthy by converting inactive Vitamin D to its active form and maintain the water and pH (acidity / alkalinity) balance of the body.

The waste products accumulate in kidney disease and lead to different symptoms

When kidneys become diseased or damaged, waste products and fluids build up in the body. You could have nausea or loss of appetite. You could also feel weak and irritable. There is water retention in the limbs or generally throughout the body called (oedema). The blood pressure can be raised (hypertension) and decreased production of red blood cells can lead to lowering of haemoglobin (anaemia).

On testing blood and urine samples, the following changes may be seen :

Albuminuria or Proteinuria - Albumin, a vital protein
   component is    lost in the urine.

Hypoalbuminaemia - Inadequate amount of protein in 
   the blood.

Hyperlipidaemia - excess of fats in the
   blood.

Anaemia - Decrease in the number of red blood
   corpuscles.

Hypocalcaemia - Inadequate amount of calcium in
   the blood.

Hyperkalaemia - Increase in the level of potassium in
   the blood.

The blood also has elevated levels of urea, creatinine.

Kidney Disease in Brief :

The two most common causes of kidney disease are Diabetes and High blood pressure. Inflammation of kidney called Glomerulonephritis or infection of the kidney called Pyelonephritis can also lead to kidney failure.

The kidney diseases which are likely to interest you are briefly mentioned.

Acute & Chronic Glomerulonephritis :

This is due to inflammation of the " Glomerulus ". Most kidney diseases attack the nephron causing them to loose their filtering capacity. This usually is a slow, gradual process and can sometimes take many years. Sometimes it can also happen in a short span of time. Glomerulus forms the sieve part of the nephrons. Depending on the extent of the inflammation either the glomerulus can recover completely or partially or not at all. This inflammation usually can occur three to four weeks after an attack of sore throat or tonsillitis. If they are destroyed by this inflammation, kidney failure sets in. Usually an acute glomerulonephritis recovers in 2-3 weeks. Acute glomerulonephritis can lead to long term changes. If the glomeruli are damaged, they slowly become completely burnt out over months or years. This irrecoverable damage is called "Chronic Glomerulonephritis ".

Pyelonephritis :

E.Coli is the commonest organism causing Urinary Tract Infection (UTI)

This usually can start as a urinary tract infection (UTI). The infection affects the kidney and the renal tubules are destroyed. Over years, the urine's concentrating capacity can be lost. This Leads to dehydration and salt loss and eventually leading to kidney failure.

Diabetes & Kidney disease :

There are two types of Diabetes Mellitus. One is dependent on Insulin and other is not dependent on Insulin

In almost 25% of all diabetics kidneys can get affected at some stage leading to kidney failure. Usually this is a very gradual process. The incidence of kidney diseases in diabetes is even higher if there is associated hypertension (raised blood pressure).

Nephrotic Syndrome :

A syndrome is a combination of signs and symptoms characteristic of a specific condition

Large number of kidney disease patients develop this syndrome. In this condition large amount of proteins are lost in the urine. Normally less than 200mg of protein is lost in the urine whereas in nephrotic syndrome as much as 30 gms of protein can be lost in the urine every day. As a result, the level of proteins in the blood falls and this produces swelling of the face and body (called oedema) due to retention of water or fluid. Nephrotic syndrome can happen if there is associated inflammation of kidney (Glomerulonephritis). The Glomerulus normally has a 'sieve' like structure and when blood passes through the glomerulus the water and minerals escape through this sieve. The size of holes in the sieve are very small and through this the larger protein molecules do not escape. In some types of glomerulonephritis the size of these holes increase leading to loss of protein or albumin in the urine.

Polycystic Kidney Disease :

This is an inherited condition. In this condition many cysts (small bags filled with watery fluid) replace the normal kidney substance. This condition affects both the kidneys and usually the size of the kidney can be twice or thrice their normal size.

Polycystic kidney disease can present in children or adults. The disease can be silent for many years and first present after the age of forty years with increased blood pressure and anemia.

Other Causes of Kidney Failure :

Some commonly available medicines which are taken to reduce pain can cause kidneys to fail if taken regularly. If you are taking pain killers regularly you should check with your doctor and ask him if they are likely to affect the kidneys.

Kidney Biopsy :

Biopsy means taking a small piece of tissue from the organ and examining it under the microscope to learn about the nature of the disease affecting the organ.

To find out about the exact nature and cause of kidney disease your doctor may want to remove a small piece of kidney tissue and examine it under the microscope. To obtain this tissue samples the doctor will perform a kidney (also called Renal) biopsy. This is done as a hospital procedure in the x-ray department. The needle used for biopsy is small in size and takes out a 2 to 3cm piece of tissue. Before doing a biopsy the doctor will do a few blood test and give local anaesthesia so that you don't feel the pain.

Dialysis using a filtering process of the blood by a machine is called haemodialysis. Dialysis using the natural filtering membrane of the body called "Peritoneum" is called Peritoneal Dialysis.

In serious kidney disease, kidney function is impaired or totally lost. In such a situation, it is by the process of "Dialysis" that waste products and excess fluids are removed from the blood.

There are two types of dialysis:

Haemodialysis

Peritoneal dialysis

Each method has it own advantages and disadvantages but it is the medical condition & attitude that will decide which method will suit you best.

CAPD or Peritoneal dialysis is required to be done daily or only in night via a machine.

Peritoneal dialysis is also a process by which waste products and excess fluids are removed from the blood, but unlike haemodialysis where the blood passes through a machine, peritoneal dialysis is done inside the body. However peritoneal dialysis has to be done daily three to four times, unlike haemodialysis which is done 2-3 times a week.

There are 2 types of peritoneal dialysis:

Continuous ambulatory peritoneal dialysis (CAPD)

Continuous cycling peritoneal dialysis (CCPD)

The peritoneal dialysis exchange procedure consists of 3 steps :

Infusion - A sterile, dialysis solution flows into your peritoneal cavity by gravity via a catheter or tube which has been surgically placed into the abdomen. The filling takes about 10 minutes. Once the filling is complete, the catheter is shut so that it does not leak.

Dwell - The lining of the peritoneal cavity called the peritoneum acts as a natural filter. It lets the waste products and excess fluids in the blood filter through into the dialysis solution, while holding back important substances that the body needs. The length of time varies from 3 - 6 hours. While the solution is in the body you can move about.

Drain - The dialysis solution containing the wastes is drained again by gravity from your body through the catheter into an empty bag. This takes about 10-20 minutes. The bag containing waste products is replaced by a bag containing sterile dialysis solution. The whole process is then repeated. Each of these replacements is called a ' Bag Exchange'.