What do the kidneys do?

Although the kidneys are small organs by weight (about ½ percent of the total body weight), they receive a huge amount of blood Ð 20-25 percent of the total arterial blood pumped by the heart. The large blood supply to the kidneys enables them to complete the following functions:

• Maintaining the balance of fluid in the body.

• Keeping the concentrations of various ions and other important substances constant.

• Regulation of the composition of blood.

• Removal of wastes from the body (urea, ammonia, drugs, toxic substances).

• Keeping the acid/base concentration of your blood constant.

• Helping regulate blood pressure.

• Stimulating and controlling the making of red blood cells.

• Regulation of the body's calcium levels.

All day every day, our body breaks down active tissues (such as muscles), and breaks down food for energy and self-repair. After the body has taken what it needs from food, the waste material is sent to the blood. If the kidneys would not remove these wastes, they would build up in the blood and damage the body. The main function of the kidneys is to remove this waste material from the blood and return the cleaned blood back to the body. Each minute about one litre of blood Ð one fifth of all the blood pumped by the heart Ð enters the kidneys through the renal arteries. After the blood is cleaned, it flows back into the body through the renal veins. This removal of wastes occurs in tiny units inside the kidneys called Nephrons. Each kidney contains about one million of these nephrons. Each nephron is made up of a very small filter, called a glomerulus (a tiny blood vessel or capillary), that is attached to a tubule. As blood passes through the nephron, this filter keeps normal proteins and cells in the bloodstream, allowing extra fluid and wastes to pass through. Much of the fluid is then returned to the blood, while the waste products are concentrated in any extra fluid as urine. When the bladder is full, the urine passes out of the body through another tube called the urethra. Another important function of the kidneys is the production of three important hormones:

• Erythropoietin (EPO): stimulates the bone marrow to make red blood cells.

• Renin: regulates blood pressure.

• Calcitriol: (a form of Vitamin D) helps the intestine to absorb calcium from the diet.

When the kidney function is healthy, excess minerals and waste products leave the body in urine. Minerals are vital in helping our bodies produce energy, growth, and are vital for the reproduction and health of our cells. Sodium (salt) and potassium are minerals that come from food. The body needs these minerals to maintain good health but they must be kept at the correct level. The kidneys also help regulate the levels of other minerals such as calcium and phosphate, which are important in the formation of bone.

Many waste products are toxic if they are not removed from the body. Urea and other waste products are made when the body breaks down protein. Creatinine is a waste product made by the muscles. Healthy kidneys take creatinine out of the blood and put it into the urine to leave the body. When kidneys are not working well, creatinine builds up in the blood.

The urinary system

The kidneys are part of the urinary system. It consists of two kidneys, two ureters, the bladder and urethra. The kidneys form the urine and account for the other functions attributed to the urinary system. From the kidneys, urine travels down two thin tubes called ureters to the bladder. Muscles in the ureter walls constantly tighten and relax to force urine downward away from the kidneys. If urine is allowed to stand still, or back up, a kidney infection can develop. Small amounts of urine are emptied into the bladder from the ureters about every 10 to 15 seconds. When the bladder is full, it contracts and empties through the urethra. The urinary system is the most vital part of our body’s cleansing systems, which includes the lungs, skin and intestines. All these organs excrete waste and water to maintain the chemical and fluid balance in the body. Kidney failure, urinary infections, kidney or bladder stones, prostate enlargement and bladder control dysfunction are some of the urinary tract problems that can be experienced.
 

Urine consists of water and dissolved waste material from what we have been drinking and eating. It also includes dead blood cells and other material the body wants to eliminate. The kidneys process the blood plasma, allowing water, sugars, vitamins, amino acids and other vital substances back into the bloodstream. They eliminate excess water, salts and minerals, which are excreted in the urine. Urine consists of:

• 95% of water
• 2.5% of urea (formed from protein breakdown)
• the remaining 2.5% is a mixture of:

          > dissolved chemicals such as sodium, potassium and creatinine (formed from muscle breakdown), along with other chemical compounds
          > minerals and ezymes
          > uric acid (produced when the body breaks down a chemical byproduct of proteins called "purine")
          > and urochrome (a yellow pigment that comes from the processing of dead blood cells in the liver.
 

The urochrome gives the urine a pale yellow color, which is its normal color.

Normally a human passes from 750-1500 milliliters of urine in a day. The requirements of water increase after consumption of fried or highly spiced foods. This will result in an increase in the total quantity of urine. On the other hand, in summer a large proportion of body water is lost through perspiration, thus decreasing the amount of urine. More urine is passed during the colder periods of the year than during the hotter parts. Generally urine is clear like pure water, or slightly yellow. When the quantity of urine decreases, because of hot weather for instance, the concentration of substances in the urine increases, which will probably result in a more deeper yellow or orange urine color. The urine of a person suffering from jaundice is generally as yellow as turmeric, and that of a feverish person has a reddish tint. Disorders of the kidneys or the urinary tract may cause urine to become cloudy and red in color. When a doctor takes a urine sample, the results reveal how well the kidneys are working. For example, blood, protein, or white blood cells in the urine may indicate injury, inflammation, or infection of the kidneys. Whereas glucose in the urine may be an indication of diabetes.

The kidney function is referred to in the medical world as "renal function". This term is used to describe the efficiency of the kidneys to filter waste. People with two healthy kidneys have 100 percent of their kidney function. Small or mild declines in kidney function - as much as 30 to 40 percent! - would rarely be noticeable. Most people with reduced kidney function have some sort of kidney disease, which will eventually get worse. Serious health problems occur when people have less than 25 percent of their kidney function. But when that function drops below 10 to 15 percent, some form of renal replacement therapy is required. This is either in the form of blood-cleansing treatments called dialysis or a kidney transplant. A person can lead an active, normal life with only one kidney. Some people are born with only one kidney and lead normal, healthy lives. Studies have shown that one kidney is sufficient to keep the body healthy. In fact you only need about 20 percent funtion to live. Every year, thousands of people donate one of their kidneys to someone in need of a healthy kidney. The recipient is often a blood relative or someone who is close to the donor, such as a spouse or friend. After recovering from surgery, a donor can work, drive, exercise and participate in sports, though contact sports are not recommended. Also, being a donor does not impact a person’s ability to have a child. There are some precautions though, for people who have only one kidney:

• Maintain a healthy lifestyle: eat healthy, exercise, keep your weight in check, drink plenty of water and get regular medical check-ups.
• Avoid smoking. Smoking slows the flow of blood to the kidneys. When less blood reaches the kidneys, it impairs their ability to function properly. Smoking also increases the risk of kidney cancer.
• Monitor your blood pressure. High blood pressure is actually the most common cause of kidney damage and people with one kidney are already at risk for developing high blood pressure. Be careful with medications that affect the blood pressure and consult your doctor how to keep it balanced (adapting lifestyle and diet).
• Have your kidney function checked on a regular basis.
• People with one kidney are at risk for proteinuria. This is a condition where high levels of protein are found in the urine, because too much protein leaks from the blood into the urine. The filtering function of the kidney is decreased. Symptoms are swellings of hands, face, abdomen or feet and foamy urine. To prevent or treat proteinuria consult with your doctor about dietary adjustments.
• Protect your kidney and be careful to engage in sports or activities that might be harmful.
• It is important to be aware of symptoms of kidney failure (see below). If you experience symptoms, difficulties or have concerns, don't hesitate to seek medical assistance.

What causes kidney failure?

Kidney failure can occur from an acute situation or from chronic problems.

− In acute kidney failure, kidney function is lost rapidly and can occur from a variety of insults to the body. For instance, because of an accident, losing a lot of blood, or after complicated surgery. But also because of an obstruction, poisoning or certain medications. Acute kidney failure is a very serious condition. If the damage is too great, this condition will lead to permanent loss of kidney function. Otherwise, the damage may still be reversed.

− More often, however, people develop kidney problems slowly, and over time. This is called chronic kidney failure: a gradual decline in kidney function and urine output over time. Sometimes people are even unaware that they have a kidney disease. This is because the kidneys are very adaptable: even when most of a kidney is not functioning, the remaining portion will increase its activity and compensate for the loss.

There are five stages of kidney disease:

Stage 1: Kidney damage, but kidney function is still normal.

Stage 2: Mild kidney disease, which can lead to increased blood pressure and frequent urination at night.

Stage 3: Moderate kidney disease, which can lead to mild anemia and increased risk of heart attacks, strokes and other diseases.

Stage 4: Severe decline in kidney function, which leads to excessive retention of waste products in the body (a condition called "uremia"), for which heamodialysis or peritoneal dialysis is necessary.

Stage 5: Kidney failure requiring dialysis or transplantation

The causes of chronic kidney failure are not always known, but the most common causes are related to:

• high blood pressure;
• diabetes;
• prostate disease;
• kidney stones.

Appropriate treatment in the early stages may slow or stop the progression of kidney failure. In many patients, chronic kidney failure does progress to what is known as end-stage renal failure (ESRF). Currently there is no cure for ESRF. The damage done to the kidneys is irreversible and dialysis or a kidney transplant is needed to replace the lost functions of the kidneys.
 

Signs and complications of kidney failure

Kidney disease attacks the nephrons (the filters in the kidneys), causing them to lose their filtering capacity. The two most common causes of kidney disease are diabetes and high blood pressure. People with a family history of any kind of kidney problem are also at risk for kidney disease. Kidney disease develops very slow. Gradually wastes are piling up in the blood and the excretory and regulatory functions of the kidneys are starting to fail. People begin to feel ill when their kidney function has dropped to less than 10%. Toxic wastes and extra fluids begin to accumulate in the blood. One of these waste products is called creatinine. Measuring the level of creatinine in the blood gives an indication of how well or how poorly the kidneys are working.

Symptoms of kidney failure may be the following:

• Kidney failure can cause fluid to collect in the body's tissues (oedema), producing swelling and high blood pressure. Fluid in the lungs may cause difficulty in breathing and put an added strain on the heart.
• High blood pressure.
• Decreased or even no urine output. Dark colored urine.
• General ill feeling, overall malaise.
• Loss of apetite or nausea and vomiting.
• Fatigue and weakness.
• Abnormally dark or light skin.
• Muscle cramps.
• Anemia.
• Sudden weight change.
• Itching, dry skin.
• Difficulty concentrating, getting drowsy.
• Headaches or sleeping problems.
• Easy bruising, bleeding or blood in the stool.
• Pain along the side, or mid to lower back.

High blood pressure is almost always present during all stages of chronic kidney disease. Delaying further kidney damage will always involve controlling the blood pressure. Damaged kidneys may not produce enough hormones, which will lead to other complications of kidney failure. If the kidneys are not working properly the blood may not have enough red blood cells to carry the oxygen our bodies need and patients may become anemic. Without the proper amount of hormones and vitamin D, bones begin to lose calcium and become weak (osteoporosis)

Many kidney failure patients also develop cardiovascular disease. In fact, heart disease is the main cause of death for kidney patients. In the early stages of kidney disease, Ayurveda advises following a low-protein diet (see tips below), in combination with exercise (to help control blood pressure and blood sugar), and life-style adaptations (quit smoking etc, see below).

Diabetes and the kidneys

Diabetes is the number 1 cause for chronic kidney disease and end stage renal malfunction. Diabetes is a disease that affects the body’s ability to produce or use insulin. When the body turns the food eaten into energy (also called sugar or glucose), insulin is used to move this sugar into the cells. If someone produces little or no insulin, or if the body cannot use the insulin (insulin resistant), the sugar remains in the bloodstream instead of going into the cells. Over time, high levels of sugar in the blood damage tiny blood vessels throughout the body including the filters of the kidneys (nephrons). This is called diabetic kidney disease. As more damage occurs to the kidneys, more fluid and waste remain in the bloodstream instead of being removed. Keeping blood glucose levels down can delay or prevent diabetic kidney disease.

Kidney damage from diabetes happens very slowly. A person might not feel sick at all for many years. The only way to find out is by running urine and blood checks. An early sign of kidney damage is when the kidneys leak small amounts of a protein called albumin into the urine. A urine test will reveal this. With more damage, the kidneys leak more and more protein. More and more wastes build up in the blood. This damage gets worse until the kidneys fail. However, this doesn't mean that being a diabetic means this person will necessarily develop a kidney disease as well. But it does mean that he will need a treatment program as soon as possible, in order for the kidneys to function effectively. The risk is, though, that when diabetes is not yet diagnosed, the kidney function has already decreased. With an early diagnosis for diabetes all the necessary steps can be taken to prevent kidney damage. And if a slight damage is already revealed, there are still treatment options that may help prevent further damage and preserve remaining kidney function. When people with diabetes experience kidney failure, they must undergo either dialysis or a kidney transplant.

Kidney transplant and dialysis

When an individual's kidneys fail, three treatment options are available: hemodialysis, peritoneal dialysis and kidney transplantation. During a kidney transplant, a healthy kidney from a donor will be put in the place of the failed organ by a surgeon. Patients will spend a recovery time, on average, of five days in the hospital afterward. The most important complication that may occur after transplant is rejection of the kidney. The body's immune system protects against all foreign substances, such as bacteria. This defense system may recognize tissue transplanted from another person as "foreign" and act to combat this "foreign invader". For this reason it is necessary to take medications every day to prevent rejection of the new kidney.

Dialysis is an artificial system for cleansing the blood. When the kidneys fail, dialysis of some form must be performed to take over the work of the failed kidneys. There are two types of kidney dialysis: hemodialysis and peritoneal. Hemodialysis uses a machine and an artificial kidney / filter to remove toxins and excess fluids. Hemodialysis is typically done five to seven times a week, for three to five hours a day. Peritoneal dyalisis uses the peritoneum (the area behind the abdomen), which has a natural filter, a semi-permeable membrane to remove the toxins and excess fluids. The peritoneum is filled with dyalisis fluid through a catheter (a flexible tube) for a prescribed period of time. The peritoneal lining ("filter") seperates excess fluids and waste products from the bloodstream into the dialysis fluid, which is then drained out and discarded. Subsequently, the peritoneum will be filled with fresh dyalisis fluid (exchange). The purpose of both treatments is to filter the blood and remove excess fluid. In order for this to be achieved, an access needs to be made to enable the process. With hemodialysis this will be a fistula/graft which is under the skin. With peritoneal dyalisis, a catheter in the belly is used. The advantages and disadvantages of each kind of treatment affect each person differently. Persons with kidney disease should learn all they can about each method of treatment. Many patients feel that a successful kidney transplant provides a better quality of life because it allows greater freedom and often is associated with increased energy levels and a less restricted diet. There is also a reduced risk of dying from kidney disease. However, there is a shortage of organs available for donation. Many people who are candidates for kidney transplantation are put on a transplant waiting list and require dialysis until an organ is available. Besides this, not everyone is candidate for a kidney transplant. Severe health problems and old age may mean that it's safer to remain on dialysis. Furthermore, the transplantation is a major surgical procedure that has risks both during and after the surgery. And last but not least, there is the risk of rejection of the new kidney. In order to prevent this from happening, medications will have to be taken for the rest of the patient's life. In making a decision about which is is the best treatment for you, you may find it helpful to talk to people who already have had a kidney transplant, or who are on dialysis, and to discuss it of course with your doctor.

Kidney and urinary system disorders

The most serious and debilitating of kidney and urinary tract diseases include the following:

End-stage renal failure (ESRF)

See above under "chronic kidney failure".

Urinary incontinence

Bladder control problems range from urinating too frequently to actual urine leakage (urinary incontinence). These problems affect millions of people of all ages, and both sexes. Unfortunately, many people feel so ashamed that they may even hide their problem from their doctor. If your incontinence interferes with your daily life, we advise you to seek medical help as soon as possible. The symptoms of incontinence (or overactive bladder) have many causes, including:

• Side effects from medications, especially diuretics (water pills) and drugs with caffeine
• Neurological disease such as multiple sclerosis or Parkinson's disease
• Urinary tract infection or other causes of bladder irritation
• Tumors or other abnormalities in the bladder such as bladder cancer
• Inflammation of the prostate or prostate cancer in men
• Nerve damage caused by surgery, injury, or disease (such as diabetes)
• Pregnancy or recent delivery

In many cases, though, the cause is not known.
 

Kidney stones

Small, solid masses called kidney stones may form when salts or minerals, normally found in urine, become solid crystals inside the kidney. Normally, these crystals are too small to be noticed, and pass harmlessly out of the body. However, they can build up inside the kidney and form much larger stones. If a stone becomes large enough, it may begin to move out of the kidney and progress through the ureter - a tube that carries urine from the kidney to the bladder. A kidney stone can become stuck at various parts of the ureter causing pain, infection and occasionally kidney damage. Kidney stones can vary in size from a grain of sand to bigger than a golf ball. They can be smooth or they can have jagged edges. There may be a single stone or many stones.

Types of kidney stones

There are several different types of kidney stones, classified by the substances that form them. The different types include:

Calcium stones: Approximately 80% of all kidney stones are calcium stones. They are composed of calcium in combination with either phosphate or oxalate. These occur when there are excess levels of calcium circulating in the blood.

Uric acid stones: Approximately 10% of all kidney stones are uric acid stones. These occur when excess amounts of uric acid are present in the blood.

Struvite stones: Approximately 5% of all kidney stones are struvite stones. They contain the mineral magnesium and the waste product ammonia and tend to occur in people who have repeated urinary tract infections.

Cystine stones: Approximately 2% of all kidney stones are cystine stones. Cystine is a type of amino acid. People with cystine stones usually have an abnormality with the way their body processes amino acids in the diet.

Symptoms of kidney stones

The following may be signs of a kidney stone:

• extreme pain in the back or side that will not go away
• blood in the urine
• fever and chills
• vomiting
• urine that smells bad or looks cloudy
• a burning sensation when urinating

If these symptoms occur, consult your doctor as soon as possible.

Benign prostatic hyperplasia (prostate enlargement)

Benign prostatic hyperplasia (benign prostatic hypertrophy: BPH) is a benign enlargement of the prostate gland that can make urination difficult. It is common for the prostate gland to become enlarged as a man ages, especially after age 50. As the prostate enlarges, it gradually compresses the urethra and blocks the flow of urine (urinary obstruction). When a person with BPH urinates, the bladder may not empty completely. Consequently, urine stagnates in the bladder, making him susceptible to urinary tract infections and bladder stones. Prolonged obstruction can damage the kidneys. The most common symptoms of BPH stem from obstruction of the urethra and gradual loss of bladder function, and involves changes or problems with urination, such as: