The kidney acts as a filter. Approximately 1 800 liters of blood is filtered in the kidneys every 24 hours. Healthy kidneys have several important functions, including the production of urine:
- Maintaining the balance of water by removing excess fluid from the body.
- Removing waste products. A living body is dependent upon several chemical reactions to take place. This process is called metabolism, which results in waste products that become toxic if they are accumulated in the body. Healthy kidneys filter the blood to remove waste products such as urea and creatinine.
- Maintaining normal body chemistry. A number of solutes such as potassium, sodium, phosphorus, calcium, bicarbonate, magnesium and chloride are important to blood chemistry. Healthy kidneys maintain correct levels of solutes needed and get rid of the excess.
The kidneys also produce three important hormones:
- Erythropoietin: controls the production of red blood cells, in the bone marrow, to prevent anemia.
- Active vitamin D: absorbs calcium from food. Bones need calcium to stay strong and healthy.
- Renin: regulates blood pressure.