Kidney Health

The kidneys perform a wide range of vital functions in the healthy body, such as:

• Removing wastes and water from the blood
• Balancing chemicals in your body
• Releasing hormones
• Helping control blood pressure
• Helping to produce red blood cells
• Producing the active form of vitamin D, which keeps the bones strong and healthy .

The kidneys remove wastes and excess water (fluid) collected by, and carried in, the blood as it flows through the body.

About 190 litres (335 pints) of blood enter the kidneys every day via the renal arteries. Millions of tiny filters, called glomeruli, inside the kidneys separate wastes and water from the blood.Most of these unwanted substances come from what we eat and drink. The kidneys automatically remove the right amount of salt and other minerals from the blood to leave just the quantities the body needs.

The cleansed blood returns to the heart and recirculates through the body. Excess wastes and fluid leave the kidneys in the form of urine. Urine is stored in the bladder until it is full and then leaves the body via the urethra. Most people pass about 2 liters (4 pints) of urine every day.

By removing just the right amount of excess fluid, healthy kidneys maintain what is called the body's fluid balance. In women, fluid content stays at about 55% of total weight. In men, it stays at about 60% of total weight. The kidneys maintain these proportions by balancing the amount of fluid that leaves the body against the amount entering the body.

Fluid comes into our bodies from what we drink, and from high-liquid foods such as soup. If we drink a lot, healthy kidneys remove the excess fluid and we pass a lot of urine. If we don't drink much, the kidneys retain fluid and we don't pass much urine. Fluid also leaves the body through sweat, breath, and feces. If the weather is hot and we lose a lot of fluid by sweating, then the kidneys will not pass so much urine. As your kidneys fail, maintaining this balance becomes more difficult. You may suffer symptoms of too much fluid. You may need to watch your diet and what you drink to maintain fluid balance.

One of the important functions of the kidneys is to regulate blood pressure. Healthy kidneys make hormones such as renin and angiotensin. These hormones regulate how much sodium (salt) and fluid the body keeps, and how well the blood vessels can expand and contract. This, in turn, helps control blood pressure. They do this by regulating:

• The amount of water in the body. If there is too much water in the body (fluid overload) blood pressure will go up. If there is too little water in the body (dehydration) the blood pressure will drop.
• The width of the arteries. The arteries constantly change in width as blood flows through them. The narrower the arteries, the higher the blood pressure. Renin helps control narrowing of the arteries. Failing kidneys often make too much renin. This raises blood pressure. If your blood pressure is high, your heart is working harder than normal to pump blood through your body.

High blood pressure (also called hypertension) caused by a breakdown in these functions is common in people with kidney failure. It is also a complication, a secondary condition caused by kidney failure.

Kidneys help make red blood cells.Healthy kidneys produce a hormone known as erythropoeitin (EPO), which is carried in the blood to the bone marrow where it stimulates the production of red blood cells. These cells carry oxygen throughout the body. Without enough healthy red blood cells you develop anemia, a condition which makes you feel weak, cold, tired, and short of breath.

Healthy kidneys keep bones strong by producing the hormone calcitriol. Calcitriol maintains the right levels of calcium and phosphate in the blood and bones. Calcium and phosphate balance are important to keep bones healthy. When the kidneys fail they may not produce enough calcitriol. This leads to abnormal levels of phosphate, calcium, and vitamin D, causing renal bone disease.

It's apparent that kidney health is of utmost importance.