What does the kidney excrete?

Nitrogenous Waste Products

- Urea: formed in the liver from protein catabolism.

- Creatinine: produced by muscle catabolism.

- Uric acid: formed from nucleic acids and some food sources.

- Ammonia: highly toxic produced from protein catabolism, normally converted into urea.

Electrolytes

- Sodium

- Potassium

- Chloride

- Bicarbonate

Other Substances

- Water: makes up the bulk of urine output, regulated by the body to maintain fluid balance.

- Hydrogen ions: secreted or reabsorbed to regulate blood pH.

- Glucose: usually completely reabsorbed, but if blood glucose levels are high, some may appear in urine.

- Vitamins: may appear in urine if taken in excess.

- Drugs: some drugs and their metabolites are excreted in urine.

- Hormones: some hormones, such as aldosterone and antidiuretic hormone (ADH), are excreted in urine after they have served their purpose.