1. Filtration of blood to remove waste products and excess substances 2. Regulation of blood pressure by controlling the balance of salt and water in the body 3. Production of hormones that regulate red blood cell production and calcium metabolism 4. Regulation of acid-base balance in the body 5. Removal of drugs and toxins from the bloodstream 6. Regulation of electrolyte levels, such as sodium, potassium, and phosphate 7. Maintenance of overall fluid balance in the body 8. Activation of vitamin D to help maintain healthy bones and teeth.