The kidneys are organs located retroperitoneal on both sides of the lumbar spine on the posterior wall of the abdominal cavity. Efficient kidneys are a prerequisite for health. Their impairment can be life-threatening, requiring dialysis or transplantation.

Location and kidney components

Schematic overview of the urinary system

What do kidneys do?

Fluid and Electrolyte Balance (water removal)

The kidneys regulate the balance of fluids and electrolytes (such as sodium, potassium, calcium, and phosphate) in the body. This balance is crucial for maintaining proper cell function and overall health.

Regulation of blood pressure

The kidneys help control blood pressure by regulating the volume of blood in the body and producing hormones like renin that influence blood vessel constriction and fluid retention.

Acid-Base Balance

The kidneys help regulate the body's acid-base balance by controlling the excretion of hydrogen ions and the reabsorption of bicarbonate ions, which help maintain the blood's pH within a narrow range.

Waste Excretion and Filtration

The kidneys eliminate waste products, excess medications, and substances that the body doesn't need, helping to prevent the accumulation of harmful substances in the bloodstream.

Vitamin D Activation/Metabolism

The kidneys play a role in activating vitamin D, which is essential for maintaining healthy bones and aiding in the absorption of calcium from the digestive tract.

Red Blood Cell Production

The kidneys produce a hormone called erythropoietin, which stimulates the bone marrow to produce red blood cells. Red blood cells are essential for carrying oxygen to tissues and removing carbon dioxide.