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Understanding Kidney Basics

Before delving into kidney disease, it’s essential to grasp the location and function of these vital organs. In this section, we’ll explore the kidneys’ role and potential issues that can lead to kidney disease. While some individuals develop kidney problems without a clear cause, conditions like diabetes and high blood pressure raise the risk.

What and where are the kidneys?

The kidneys, two bean-shaped organs about the size of a fist, reside just below the rib cage on either side of the spine. Their crucial functions include filtering waste products from the blood, maintaining balanced electrolyte levels, and regulating blood pressure. These vital organs help remove excess water and waste to produce urine. Chronic kidney disease (CKD) is a long-term condition where the kidneys don’t function optimally, often associated with aging and more common in certain ethnic groups. While early-stage CKD may not exhibit noticeable symptoms, advanced stages can lead to fatigue, swollen ankles, shortness of breath, and blood in the urine. Common causes of CKD include high blood pressure, diabetes, and kidney infections123. If you suspect kidney-related symptoms, consult a GP for evaluation and appropriate management. Remember, maintaining a healthy lifestyle and managing underlying conditions can help prevent CKD.

What do the kidneys do?

The kidneys are vital organs responsible for maintaining homeostasis in the body. Here’s a concise explanation:

  • Filtration: Kidneys filter blood, removing waste products (like urea and creatinine) and excess substances (such as water, electrolytes, and toxins). This process occurs in tiny structures called nephrons.
  • Fluid  Balance: Kidneys regulate fluid levels by adjusting urine production. When dehydrated, they conserve water; when overhydrated, they excrete excess fluid.
  • Electrolyte Regulation: Kidneys control electrolytes (sodium, potassium, calcium, etc.) to maintain proper balance. Imbalances can affect nerve function, muscle contraction, and heart rhythm.
  • Blood Pressure: Kidneys help regulate blood pressure by adjusting blood volume and releasing hormones (like renin) that impact blood vessel constriction.
  • Red Blood Cell Production: They produce erythropoietin, stimulating bone marrow to create red blood cells.
    In summary, kidneys filter, balance fluids, regulate electrolytes, influence blood pressure, and support red blood cell production

How Do Kidneys Work?

The kidneys function as filters, removing waste and excess fluid from the blood. Blood flows through the kidneys, where it undergoes cleansing before returning to the heart.

  • Blood Entry: The kidneys receive blood through the renal arteries.
  • Nephron Filtration: Inside the kidneys, millions of nephrons act as mini-filtering systems, sieving the blood.
  • Selective Reabsorption: Essential substances are reabsorbed, while waste products and excess fluid become urine.
  • Blood Return: Clean blood exits the kidneys via the renal veins.
  • Urine Transport: Ureters carry urine from the kidneys to the bladder.
  • Bladder Storage and Elimination: The bladder stores urine until it’s full, then releases it through the urethra.

Every day, the kidneys filter approximately 190 liters (335 pints) of blood, passing it through 145 miles (225 km) of intricate “tubes” and countless tiny filtering units known as “nephrons.

Besides filtering blood and maintaining fluid balance, the kidneys also synthesize various hormones and chemicals critical for essential bodily functions.

Erythropoietin, a hormone produced by the kidneys, travels through the bloodstream to the bone marrow. There, it stimulates the production of red blood cells. These cells play a crucial role in carrying oxygen for proper bodily function. When red blood cells are unhealthy, anaemia can occur, leading to weakness, fatigue, and shortness of breath.

Blood Pressure Regulation: Kidneys play a crucial role in controlling blood pressure. When kidneys are diseased, blood pressure tends to rise. Elevated blood pressure is significant because it increases the risk of stroke, heart disease, and further kidney damage.

Mineral Balance and Bone Health: Additionally, kidneys maintain the proper balance of calcium and phosphate in the blood and bones. They also produce vitamin D. Consequently, when kidneys fail, bone-related issues may arise.

What if you only have one kidney?

Having one kidney is more common than you might think. Some people are born with a single kidney (a condition called renal agenesis), while others may lose a kidney due to surgery, donation, or disease.

Remarkably, the remaining kidney can adapt and compensate for the loss. It increases in size and capacity to handle the workload.

With one healthy kidney, you can lead a normal life. The single kidney performs all necessary functions—filtering blood, regulating fluid balance, and maintaining electrolyte levels.

Kidney Donation: If you’ve donated a kidney, or considering donating one your remaining kidney adapts remarkably well, and most donors experience no significant health issues.

How to improve your kidneys health

Keep an eye on your blood pressure—high blood pressure speeds up kidney damage. To safeguard against kidney disease, adopt a diet low in salt and saturated fats

Keep fit and active -Stay physically active and maintain fitness. Regular exercise helps lower blood pressure, thus decreasing the risk of kidney disease

Don’t smoke - Smoking slows blood flow to the kidneys, decreasing their ability to function properly

Eat healthy and keep your weight in check -  Maintain a healthy diet and manage your weight. Doing so can help prevent conditions like diabetes, heart disease, and other kidney-related issues.

Get your kidney function checked - Consider kidney function checks if you have a family history of kidney disease, diabetes, high blood pressure, or belong to South Asian or African-Caribbean ethnic backgrounds.

Eat Keep well hydrated-  Staying well-hydrated assists the kidneys in eliminating sodium, urea, and toxins from the body, thereby reducing the risk of developing chronic kidney disease.

*Dialysis patients may need to restrict their fluid intake*

While kidney disease can affect anyone, certain factors increase the risk:

Medical Conditions: Diabetes ,High blood pressure ,Cardiovascular disease

Other Risk Factors: Family history of kidney disease, South Asian or African-Caribbean ethnic background.

Reviewed June 2024

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The National Kidney Federation cannot accept responsibility for information provided.  The above is for guidance only.  Patients are advised to seek further information from their own doctor.