Kidneys Function, Anatomy, Location, Diseases, & Tips For Health
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Dr. Muhammed
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Jul 01, 2025
What are the Kidneys?
The kidneys are two bean-shaped organs located in the back of the abdominal cavity, one on each side of the spine, just below the rib cage. Each kidney is about the size of a fist and weighs approximately 125–170 grams in adults. The kidneys are part of the urinary system and perform several essential functions that keep the body in balance. Their primary job is to filter the blood to remove waste products, excess water, and toxins, which are then excreted from the body in the form of urine.
Function
What do the Kidneys do?
Your kidneys do much more than just make urine. Their main job is to filter your blood and remove waste and extra fluids from your body. These wastes include things like urea (from breaking down protein), creatinine (from your muscles), and excess acids.
Every minute, your kidneys filter about half a cup of blood, working non-stop to keep your body in balance. They also help control blood pressure, keep your bones strong, and tell your body to make red blood cells.
How do the Kidneys work?
1- Blood enters your kidneys through a large blood vessel called the renal artery.
2- Inside each kidney, tiny filters clean the blood by removing waste and extra water.
3- The clean blood goes back to your body through another large blood vessel called the renal vein.
4- The waste and extra fluid become urine (pee).
5- Pee travels from your kidneys through thin tubes called ureters down to your bladder.
6- Your bladder stores the pee until you're ready to go to the bathroom.
What else do the Kidneys do?
Your kidneys do more than just filter waste. They help keep your whole body working properly. Here’s how:
1- They balance the pH of your blood, making sure it’s not too acidic or too basic.
2- If your blood sugar drops too low, your kidneys can make glucose to help bring it back up.
3- They produce a protein called renin, which helps control your blood pressure.
Your kidneys make two important hormones:
- Calcitriol – a form of vitamin D that helps your body absorb calcium.
- Erythropoietin tells your body to make more red blood cells.
4- Sitting on top of each kidney is an adrenal gland, which makes hormones like cortisol that help your body handle stress.
Can you Live with One Kidney?
Yes you can live a healthy, normal life with just one kidney. Many people do! In fact, your one kidney can do the work of two.
Doctors may remove a kidney in a surgery called a radical nephrectomy if needed. Some people are born with only one kidney, and others choose to donate one to help save someone else’s life.
You might have just one kidney if you:
1- Had a kidney removed because of cancer, injury, or disease
2- Donated a kidney to someone who needed a transplant
3- Were born with only one kidney (called renal agenesis)
4- Have two kidneys, but only one works properly (called kidney dysplasia)
Anatomy
Where are my Kidneys Located?
Your kidneys are located in your lower back, just below your rib cage, on both sides of your spine. You have two kidneys, one on the left and one on the right.
1- The right kidney sits a little lower than the left because of the liver above it.
2- You usually can’t feel your kidneys, but if they are hurting, you might feel pain on either side of your lower back.
What Are the Parts of the Kidney?
Your kidneys are powerful, complex organs made up of many working parts. Each part has a specific job to help clean your blood and make urine. Here are the main parts:
1- Kidney Capsule (Renal Capsule): A protective outer layer made of tissue and fat. It shields the kidney from injury and holds it in place.
2- Renal Artery: A large blood vessel that brings oxygen-rich blood into the kidney. It delivers over 5 cups (1.2 liters) of blood per minute when you're at rest.
3- Renal Cortex: The outer layer of the kidney. This is where blood is first filtered. It also produces erythropoietin (EPO) a hormone that helps your body make red blood cells.
4- Renal Medulla: The inner section of the kidney. It contains the deeper parts of the nephrons, the structures that filter blood and make urine.
5- Renal Papilla: Small, pyramid-shaped tips that pass urine into the next part of the system. These can be sensitive to dehydration or some medications like NSAIDs.
6- Renal Pelvis: A funnel-shaped area that collects urine and sends it down the ureters to your bladder.
7- Renal Vein: Once the kidney filters your blood, the clean blood leaves through this large vein and returns to your heart.
Most Common Kidney Diseases: Symptoms, Diagnosis & Treatment
Chronic kidney disease (CKD)
Overview of Chronic Kidney Disease (CKD)
Chronic Kidney Disease (CKD) is a long-term condition where the kidneys gradually lose their ability to filter waste, fluids, and toxins from the blood. In early stages, CKD often causes no noticeable symptoms, making it difficult to detect until significant damage has occurred. As the disease progresses, harmful levels of waste and fluid can build up in the body, leading to serious health complications.
Chronic Kidney Disease (CKD) Common Symptoms
Chronic Kidney Disease symptoms often develop gradually and may go unnoticed in the early stages. As kidney function declines, waste and fluid can build up in the body, leading to a wide range of signs. The severity and combination of symptoms can vary depending on how advanced the disease is. Common symptoms of CKD include:
1- Fatigue and weakness
2- Nausea and vomiting
3- Loss of appetite
4- Difficulty sleeping
5- Urinating more or less than usual
6- Swelling in the feet and ankles
7- Muscle cramps
8- Dry, itchy skin
9- Difficulty concentrating or mental fog
10- High blood pressure that’s hard to control
11- Shortness of breath from fluid buildup in the lungs
12- Chest pain if fluid builds around the heart
Chronic Kidney Disease (CKD) Diagnosis
Doctors use blood tests to measure creatinine and calculate the glomerular filtration rate (GFR), which tells how well your kidneys are filtering. A urine test can also detect protein leakage (albuminuria), a sign of kidney damage. Imaging tests like ultrasound may be used to examine kidney structure.
Chronic Kidney Disease (CKD) Treatment
1- CKD cannot be reversed, but its progression can be slowed. Treatment includes:
2- Managing diabetes or high blood pressure
3- Eating a kidney-friendly diet
4- Taking prescribed medications
5- Preparing for dialysis or transplant in advanced stages
Kidney Stones
Overview of Kidney Stones
Kidney stones are hard mineral and salt deposits that form inside the kidneys when urine becomes too concentrated. Also known as renal calculi or nephrolithiasis, these stones can develop due to factors like diet, obesity, certain medical conditions, medications, or low fluid intake.
They can affect any part of the urinary tract, from the kidneys to the bladder. Passing a kidney stone can be very painful, but in many cases, drinking plenty of water and using pain relievers is enough. In more serious cases, surgical or advanced treatments may be required, depending on the stone’s size, type, and location.
Kidney Stones Common Symptoms
Kidney stones usually don’t cause symptoms until they begin to move within the kidney or pass into the ureters, the narrow tubes that connect the kidneys to the bladder. When a stone gets stuck, it can block urine flow, causing swelling and intense pain
Common symptoms include:
1- Sharp, severe pain in the side and back, just below the ribs
2- Pain that spreads to the lower abdomen and groin
3- Pain that comes in waves and varies in intensity
4- Burning or pain during urination
Other signs may include:
1- Pink, red, or brown urine (blood in urine)
2- Cloudy or bad-smelling urine
3- Frequent urge to urinate, or passing small amounts of urine
4- Nausea and vomiting
5- Fever and chills, especially if there's an infection
Kidney Stones Diagnosis
Doctors often begin with urine and blood tests to detect signs of infection, blood, or excess minerals linked to stone formation. Imaging tests such as a non-contrast CT scan, ultrasound, or X-ray are used to locate the stone, determine its size, and check for blockages. Accurate diagnosis is essential to choose the right treatment.
Kidney Stones Treatment
Kidney stone treatment depends on the size, type, and location of the stone. Small stones often pass on their own with increased fluid intake, pain relievers, and possibly medications to relax the urinary tract. Larger or more stubborn stones may require medical procedures such as shock wave lithotripsy (SWL) to break the stone into smaller pieces, ureteroscopy to remove or fragment it, or, in rare cases, surgery.
Polycystic Kidney Disease (PKD)
Polycystic Kidney Disease (PKD) is a genetic disorder where fluid-filled cysts grow inside the kidneys, causing them to enlarge and lose function over time. These cysts are noncancerous but can multiply and damage the surrounding kidney tissue.
PKD can affect one or both kidneys and may also lead to problems in other organs, such as the liver or blood vessels. It is a progressive disease, meaning it worsens over time, often leading to chronic kidney disease or even kidney failure if not managed properly.
Polycystic Kidney Disease (PKD) Symptoms
Many people with PKD don’t notice symptoms early on. However, as the cysts grow and put pressure on kidney structures, symptoms begin to appear. Common symptoms include:
1- High blood pressure (often the first noticeable sign)
2- Pain in the back, side, or abdomen
3- Blood in the urine (hematuria)
4- Frequent kidney infections
5- Increased abdominal size due to enlarged kidneys
6- Urinary tract infections (UTIs)
7- Fatigue or feeling generally unwell
Polycystic Kidney Disease Diagnosis
PKD is usually diagnosed through imaging tests such as ultrasound, CT scan, or MRI, which detect cysts in the kidneys. In some cases, genetic testing may be recommended, especially if there is a family history of PKD. Blood and urine tests are also used to monitor kidney function and check for complications.
Polycystic Kidney Disease Treatment
There is currently no cure for polycystic kidney disease, but treatment focuses on managing symptoms and slowing disease progression. This includes controlling high blood pressure, treating infections promptly, and following a kidney-friendly diet. In advanced cases, dialysis or a kidney transplant may be needed. Newer medications, such as tolvaptan, may help slow the growth of cysts in certain patients.
How can I keep my kidneys healthy?
Keeping your kidneys healthy is essential for your overall well-being. Here are key habits to protect them and keep them working at their best:
1- Stay well-hydrated: Drinking enough water helps your kidneys flush out toxins and prevent kidney stones. Aim for 6-8 glasses of water a day, unless your doctor advises otherwise.
2- Manage blood pressure and blood sugar: High blood pressure and diabetes are the leading causes of kidney damage. Regular monitoring and medication (if needed) can protect your kidneys.
3- Eat a balanced, kidney-friendly diet: Choose foods low in salt, saturated fats, and added sugars. Eat more fruits, vegetables, whole grains, and lean proteins. If you have kidney disease, follow your doctor’s specific dietary advice.
4- Exercise regularly: Physical activity supports healthy blood pressure and weight, both of which benefit your kidneys.
5- Avoid smoking and limit alcohol: Smoking reduces blood flow to the kidneys and speeds up kidney damage. Excessive alcohol can also strain kidney function.
6- Use medications wisely: Overusing painkillers like ibuprofen or aspirin can harm your kidneys over time. Always follow the dosage and talk to a healthcare provider if you're taking them regularly.
7- Get regular checkups: If you have risk factors like diabetes, high blood pressure, or a family history of kidney disease, ask your doctor for routine kidney function tests.
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