Kidney is one of the main parts of our excretory system. Failure of the kidneys to function properly will obstruct the entire excretory system. And this may lead to the occurring of water retention. Let’s take a look at the kidney and its function as it will help you to better understand how and what causes water retention in patients with kidney problems.

Kidneys inside our body

  • Our kidneys are two bean-shaped organs which are located near the middle of the back; one on each side.
  • Each kidney contains about 1 million nephrons. The nephron is a tiny excretory unit of the kidney. Each nephron is made up of a:
    • Bowman’s capsule: the cup-shaped end of a nephron.
    • Tubule: tiny urine-collecting tube.
    • Glomerulus: a tangled mass of blood capillaries enclosed by the bowman’s capsule of a tubule.

How the kidneys work?

Blood enters the glomerulus of the kidneys through arteries. Water, small molecules and ions of the blood are filtered from the glomerulus into the Bowman’s capsule. This fluid is called glomerular filtrate (nephric filtrate). The glomerular filtrate passes along the length of the nephron (tubule). Here, most of its water, salts, glucose, and amino acids, are reabsorbed into the surrounding blood capillaries. The resulting concentrated solution of waste materials and chemicals passes through the tubule and is released as urine into the ureter.

Functions of the kidneys

  • Filter and remove excess fluid, waste and toxic substances from the blood as urine.
  • Regulate the chemical composition of blood such as salt, potassium and acid.
  • Secrete three important hormones:
    • Erythropoietin: hormone which is needed to stimulate the production of red blood cells.
    • Renin: hormone that helps to control the blood pressure.
    • Active vitamin D: hormone that helps to regulate absorption of calcium and form b bones.

What causes water retention in kidney patients?

Many factors can cause the kidneys lose ability to carry out their vital functions. When the kidneys fail to function normally, many symptoms will be present. One of the symptoms is fluid retention especially in legs, feet or ankles and potentially in the hand, face or body cavity. So, what causes water retention in kidney patients? Well, water retention occurs in patients with kidney problems because of two main reasons:

  • The glomerulus gets leaky and causes an excessive loss of protein through the kidneys. The protein helps to hold salt and water in the bloodstream. If the protein level is too low, fluid is accumulated and leak out into the body tissues.
  • The kidneys lose its ability to excrete salts into the urine thus lead to fluid accumulation in the body.

For more information about kidney problems and diseases with swelling symptom you can continue to Kidney Failure, Diseases and Water Retention.