top of page
Kidney basics

  KIDNEY BASICS  

UNDERSTANDING THE IMPORTANCE OF YOUR KIDNEYS AND HOW THEY WORK

BASICS

What are kidneys

What are Kidneys

The kidneys are two bean-shaped organs located on either side of the spine, just below the rib cage. They are part of the urinary system and perform several essential functions in the body.

HOW

HOW DO KIDNEYS WORK

The kidneys are vital organs responsible for maintaining the body's fluid balance, filtering waste products from the blood, regulating electrolyte levels, and producing urine.

Here is a simplified explanation of how the kidneys work:
ggg.png
FILTRATION

The blood enters the kidneys through the renal arteries. Inside each kidney, there are millions of tiny filtering units called nephrons. Each nephron consists of a glomerulus and a tubule. The glomerulus is a network of tiny blood vessels called capillaries. As blood passes through the glomerulus, waste products, excess water, and other substances are filtered out of the bloodstream into the tubule.

ggg.png
REABSORPTION

The filtrate that enters the tubule contains both waste products and essential substances that the body needs, such as glucose, salts, and water. As the filtrate moves through the tubule, the kidneys selectively reabsorb these necessary substances back into the bloodstream. This process helps maintain the body's proper balance of electrolytes and fluid.

ggg.png
SECRETION

In addition to reabsorption, the tubules also play a role in secreting certain substances into the urine. This includes waste products and excess substances that need to be eliminated from the body, such as drugs or toxins.

ggg.png
CONCENTRATION

As the filtered fluid (now called urine) moves through the tubules, the kidneys have the ability to adjust its concentration based on the body's needs. This is achieved by reabsorbing or excreting water and electrolytes, particularly under the influence of hormones like antidiuretic hormone (ADH).

ggg.png
URINE FORMATION AND EXCRETION

After passing through the tubules, the urine collects in the renal pelvis, which is a central cavity in the kidney. From there, it travels through the ureters to the bladder, where it is stored until it is eliminated from the body through the urethra during urination.

Kidneys have many roles in the body, the main ones being:
ggg.png
FILTRATION AND WASTE REMOVAL

The primary function of the kidneys is to filter waste products, excess water, and toxins from the blood. They remove substances such as urea, creatinine, and uric acid, which are by-products of metabolism and harmful if accumulated in the body.

ggg.png
FLUID CONTROL

The kidneys regulate the body's fluid balance by adjusting the amount of water excreted through urine.

ggg.png
URINE PRODUCTION AND EXCRETION

The kidneys filter the blood, remove waste products, and produce urine. Urine is then transported through the urinary tract and excreted from the body during urination.

ggg.png
ELECTROLYTE BALANCE

They also help maintain the proper balance of electrolytes, such as sodium, potassium, calcium, and phosphate, which are essential for nerve function, muscle contraction, and other vital processes.

In addition to their role in filtration and urine production, the kidneys are involved in several other important functions, including:
ggg.png
REGULATION OF BLOOD PRESSURE

The kidneys help regulate blood pressure by controlling the balance of salt, water, and hormones involved in blood vessel constriction and fluid volume.

ggg.png
ACID-BASE BALANCE

The kidneys regulate the body's acid-base balance by reabsorbing bicarbonate ions and excreting hydrogen ions, helping to maintain the blood's acidity level or pH within a narrow range.

ggg.png
HORMONE PRODUCTION

The kidneys produce and release important hormones, such as erythropoietin (EPO), which stimulates the production of red blood cells, and renin, which plays a role in regulating blood pressure.

ggg.png
VITAMIN D ACTIVATION

The kidneys play a role in activating vitamin D, a hormone necessary for the absorption of calcium and phosphorus in the intestines. Adequate levels of vitamin D are essential for bone health and other physiological processes.

ggg.png
DETOXIFICATION

Along with the liver, the kidneys help eliminate various drugs, toxins, and foreign substances from the body.

Overall, the kidneys play a vital role in maintaining the body's internal environment and ensuring its proper functioning.

WHAT

WHAT HAPPENS WHEN KIDNEYS DO NOT WORK PROPERLY?

When the kidneys do not work properly, it can lead to a condition known as kidney failure or renal failure. Kidney failure can occur suddenly (acute kidney failure) or develop over a long period (chronic kidney failure).

Here are some of the consequences and symptoms that can occur when the kidneys do not function properly:
ggg.png
DECREASED FILTRATION AND WASTE BUILD-UP

When the kidneys are unable to effectively filter waste products and toxins from the blood, these substances can accumulate in the body. This can lead to symptoms such as fatigue, nausea, vomiting, loss of appetite, and a metallic taste in the mouth.

ggg.png
FLUID AND ELECTROLYTE IMBALANCE

Impaired kidney function can disrupt the balance of fluids and electrolytes in the body. This may result in fluid retention, swelling (edema), electrolyte abnormalities (such as high potassium or low calcium levels), and disturbances in blood pressure regulation.

ggg.png
URINE PRODUCTION AND EXCRETION PROBLEMS

Kidney dysfunction can lead to decreased urine production or the production of urine that is abnormal in quantity or composition. This can result in changes in urinary frequency, colour, or consistency.

ggg.png
ACID-BASE IMBALANCE

The kidneys play a crucial role in maintaining the body's acid-base balance. When they are not functioning properly, it can lead to an accumulation of acid in the blood (acidosis) or alkaline imbalances, which can affect various body systems and lead to symptoms such as confusion, lethargy, and abnormal heart rhythms.

ggg.png
ELEVATED BLOOD PRESSURE

The kidneys play a role in regulating blood pressure. When they are impaired, it can lead to high blood pressure (hypertension), which can further damage the kidneys and other organs.

ggg.png
ANEMIA AND FATIGUE

The kidneys produce the hormone erythropoietin (EPO), which stimulates the production of red blood cells. In kidney failure, the production of EPO is reduced, leading to a decrease in red blood cell production and anemia. This can cause fatigue, weakness, and shortness of breath.

ggg.png
BONE AND MINERAL DISORDERS

The kidneys help regulate the levels of calcium and phosphorus in the body. When they are not functioning properly, it can lead to imbalances in these minerals, resulting in bone problems such as bone pain, bone loss (osteoporosis), and an increased risk of fractures.

ggg.png
ACCUMULATION OF TOXINS

Without proper filtration and excretion, toxins and waste products can accumulate in the body, affecting various organs and systems. This can lead to symptoms such as neurological changes, itching, skin discoloration, and gastrointestinal disturbances.

It's important to note that the symptoms and consequences of kidney dysfunction can vary depending on the severity and underlying cause of the condition. If you suspect any issues with kidney function, it is crucial to consult a healthcare professional for proper diagnosis and management.

WHAT

WHAT IS CHRONIC KIDNEY DISEASE (CKD)?

Chronic kidney disease (CKD) is a long-term condition in which the kidneys gradually lose their ability to function properly. It is a progressive and irreversible condition that can lead to kidney failure if not managed appropriately. CKD is categorised into different stages based on the level of kidney function, with stage 1 being the mildest and stage 5 representing kidney failure.

Common causes of chronic kidney disease include:
ggg.png
DIABETES

Diabetes is the leading cause of CKD. High levels of blood sugar over time can damage the small blood vessels in the kidneys, impairing their ability to filter waste and toxins effectively.

ggg.png
HYPERTENSION (HIGH BLOOD PRESSURE)

Uncontrolled or poorly managed high blood pressure can damage the blood vessels in the kidneys, reducing their ability to function properly.

ggg.png
GLOMERULONEPHRITIS

This refers to inflammation of the kidney's filtering units, called glomeruli. Glomerulonephritis can be caused by infections, immune system disorders, or other conditions.

ggg.png
POLYCYSTIC KIDNEY DISEASE (PKD)

PKD is an inherited condition characterised by the growth of fluid-filled cysts in the kidneys. These cysts can gradually replace healthy kidney tissue, leading to CKD.

ggg.png
OTHER FACTORS

Other factors that can contribute to CKD include recurrent kidney infections, urinary tract obstruction, kidney stones, certain medications, autoimmune diseases, and systemic conditions that affect multiple organs.

Symptoms of chronic kidney disease may not appear until the disease has progressed to an advanced stage. Some common signs and symptoms include:

Fatigue and weakness

Swelling in the legs, ankles, or feet (edema)

Increased or decreased urine output

Blood in the urine

Foamy or bubbly urine

Frequent urination, especially at night

Persistent itching

Muscle cramps

Loss of appetite and unintentional weight loss

Difficulty concentrating and mental fog

Sleep disturbances

High blood pressure

If you experience any of these symptoms or have risk factors for CKD, it is important to see a healthcare professional for evaluation and appropriate management. Early detection and intervention can help slow the progression of CKD and reduce the risk of complications. Treatment for CKD typically involves managing underlying conditions, lifestyle modifications, medication management, and, in advanced stages, renal replacement therapies like dialysis or kidney transplantation.

WHAT

WHAT IS END STAGE RENAL DISEASE?

End Stage Renal Disease (ESRD), also known as End Stage Kidney Disease (ESKD), is the final and most severe stage of chronic kidney disease (CKD) where the kidneys have lost almost all of their function. In ESRD, the kidneys are no longer able to perform their vital functions of filtering waste products and excess fluid from the blood effectively.

ESRD is characterised by a significant and permanent reduction in kidney function, usually below 10-15% of normal capacity. At this stage, the kidneys are unable to maintain the body's internal balance of fluids, electrolytes, and waste products, requiring medical intervention to replace their function.

Common signs and symptoms of ESRD may include:

Severe fatigue and weakness

Persistent itching

Loss of appetite and unintentional weight loss

Nausea and vomiting

Difficulty concentrating and mental fog

Swelling in the legs, ankles, or feet (edema)

Shortness of breath

Changes in urine output (either increased or decreased)

Muscle cramps

Elevated blood pressure

ESRD is typically diagnosed based on clinical symptoms, blood tests to assess kidney function (such as measuring creatinine and blood urea nitrogen levels), and imaging studies. It is important to note that not all individuals with CKD will progress to ESRD, and the rate of progression varies depending on various factors such as the underlying cause, management of risk factors, and timely medical interventions.

Treatment options for ESRD include:
ggg.png
DIALYSIS

Dialysis is a procedure that artificially removes waste products, excess fluid, and toxins from the blood when the kidneys are no longer able to do so. There are two main types of dialysis: Hemodialysis (HD), which uses a machine to filter the blood, and Peritoneal Dialysis (PD), which uses the lining of the abdomen to filter the blood.  Please see our sections on HD and PD to get more detailed information regarding these treatment options.

ggg.png
KIDNEY TRANSPLANTATION

Kidney transplantation involves surgically replacing the failed kidneys with a healthy kidney from a living or deceased donor. A successful kidney transplant can restore kidney function and eliminate the need for dialysis. However, transplantation requires careful matching and lifelong immunosuppressive medications to prevent organ rejection.  Please see our sections on Kidney Transplantation to get more detailed information.

In both dialysis and transplantation, ongoing medical care, lifestyle modifications, and close monitoring are necessary to manage the complications associated with ESRD and to ensure the best possible outcomes for individuals with the condition.

It's important for individuals with CKD to work closely with their healthcare team to monitor kidney function, manage underlying conditions, and make lifestyle modifications that can slow the progression of CKD and potentially delay the onset of ESRD. Early detection and intervention are key in managing CKD and preventing its progression to end-stage renal disease.

We have provided more detailed information about the different treatments and supports for Kidney Disease patients, which can be found by clicking on the various services RHS offers and supports for patients, communities and beneficiaries.

Kidney health support

GET INVOLVED

United to help win the fight against kidney disease in Singapore.

bottom of page