What are Kidney Stones?
Kidney stones (also called renal stones, urolithiasis, nephrolithiasis) are hard deposits made of salts and minerals that form inside the kidney. Kidney stones or renal stones can affect any part of the urinary tract from the kidneys to the bladder. Often, kidney stones form when the urine becomes concentrated, allowing minerals to stick together and crystallise. Passing kidney stones can be painful, however, the stones usually cause no permanent damage if diagnosed on time.
Types of Kidney Stones
Not all kidney stones are made from the same crystals. Also, kidney stones can range in shape and size, with some as small as a grain of sand, others the size of a pebble and some growing as large as a golf ball. The types of kidney stones can be as follows:
1. Calcium stones:
The most common type of kidney stone, calcium stones form due to eating high-oxalate foods or due to lack of fluid intake. A calcium-oxalate stone is the most common type of kidney stone.
2. Uric acid stones:
Another common type of kidney stone, uric acid stones may form due to high levels of uric acid in the urine. Eating animal proteins (fish, eggs, pork, poultry, beef) causes uric acid to build-up in the urine.
3. Struvite stones:
This is the less common type of kidney stone that forms after a urinary tract infection. Caused by bacterial infections and these are slow growing stones and gradually grow to large sizes and damage the kidney at late stages.
4. Cysteine stones:
This type of stone forms in people with cystinuria, a hereditary condition that causes excess of the amino acid cysteine in the kidneys and the bladder.
Causes of Kidney Stones:
About 1 in 10 people will get a kidney stone in their lifetime. A variety of factors are associated with the formation of kidney stones, including fluid intake, life style and dietary habits, low urine volume, weight, family history, certain medications and medical conditions. If an individual’s parents had kidney stones, he/she is more likely to have them as well. Renal stones are more prevalent in men than in women, and once you’ve had a kidney stone, the risk of having another also increases.
In order to lower the chance of developing a kidney stone, it is best to avoid dehydration, which causes low urine volume. In fact, lack of water intake leads to concentrated urine, increasing the chances of renal stones forming. It's therefore important to stay hydrated, particularly in hot weather or during exercise.
In addition to this, a high intake of salt, animal protein or processed meats also elevates the risk of developing kidney stones.
Having too little or too much calcium in the diet also increases the risk of calcium oxalate stones.
Being overweight and bowel conditions like ulcerative colitis or Crohn’s disease may also increase the chances of getting kidney stones.
Kidney Stone Symptoms
Mostly commonly kidney stones are detected incidentally. Sometimes they do not cause symptoms till the time they are non obstructed or of small size.
Some of the most common kidney stone symptoms are pain in the lower back, stomach or flank pain. It can be a mild pain or a sharp and severe pain. Pain or other symptoms may vary depending upon the site of stone in the urinary tract.
Other kidney stone symptoms include:
Nausea and vomiting
Blood in the urine
Inability to urinate or pain while urinating
Frequent urination
Fever or chills (this may happen when kidney stones lead to Urinary Tract Infections)
Foul-smelling or cloudy urine
Sometimes stones may present with symptoms of kidney failure like decreased urine output, swelling over the feet, nausea, vomiting, loss of appetite etc.
Risk Factors for Kidney Stones
You might be at a greater risk for developing kidney stones if you:
Don’t drink enough water
Are obese or overweight
Eat foods high in sugars (sucrose and fructose) and salts
Have diabetes
Take a diet high in proteins
Have a family history of kidney stones
Have polycystic kidney disease
Have a blockage in the urinary tract
Have had an intestine or stomach surgery, such as gastric bypass surgery
Take medications such as diuretics, anti-seizure medications and calcium-based antacids
Medical Conditions That Elevate Kidney Stone Risk
Certain medical conditions put an individual at a higher risk of kidney stones. These include:
Point to remember:
Kidney stones can develop at any stage of life. If a child or a teen has kidney stones, make sure to consult a doctor for diagnosis and kidney stone treatment.
Kidney Stone Diagnosis and Tests
Healthcare providers use imaging, urine and blood tests to diagnose kidney stones. If the doctor detects a kidney stone based on the symptoms and physical examination, one or more of these tests may be recommended.
1. Urine test: This test detects signs of infection and stone-forming crystals in the urine.
2. Blood tests: This test detects infection, high levels of calcium, uric acid, phosphorus, and assess kidney function.
3. Imaging tests: An ultrasound, CT scans and X-rays helps detect the shape, size, location and number of stones.
4. Genetic Tests: Sometimes if stones are recurrent and especially at younger age with positive family history your doctor would like to get gene tests to look for any hereditary cause of stone formation.
5. Metabolic tests: these are done when someone is having recurrent stone formation to know the cause of stone formation, and include blood and 24 hour urine tests.
Kidney Stones Treatment Options
The treatment for kidney stones depends on:
If the kidney stone is small in size and is able to pass on its own, the doctor may recommend drinking lots of water to help move the stone through the urinary tract and out of the body. They may also recommend pain relief medicine to help manage pain and discomfort due to the renal stones. Some medicines which help expelling the stones out may also be prescribed by your doctor.
If the kidney stone is large or is blocking the urinary tract, the doctor may recommend treatment to break the stone into small pieces or remove the stone through surgery.
Kidney stone treatment options include:
1. Lithotripsy (Extracorporeal shock wave lithotripsy) [ESWL]:
Lithotripsy utilises shock waves to break down the kidney stone into smaller pieces. After the treatment, the small pieces of kidney will pass through the urinary tract through urine. Due to availability of miniature endoscopes this modality is not preferred nowadays as this is time consuming and painful.
2. Ureteroscopy (URS):
During a ureteroscopy, a doctor inserts a scope through the urethra and bladder into the ureter. Instruments passed through the scope can remove the stone (if small in size) or break the stone into small pieces using a laser (if it is large in size). Nowadays smaller scopes called flexible scopes which can go up-till kidney are available. This is called Retrograde Intrarenal Surgery (RIRS) If the stone is diagnosed in the bladder, a doctor may use a cystoscope that is inserted into the bladder. Both the procedures are performed under anaesthesia.
3. Percutaneous Nephrolithotomy (PCNL):
In some cases, the location and size of the stone requires a puncture into the kidney via a small skin hole near your back called as percutaneous nephrolithotomy. During this procedure, an ultrasound probe breaks and removes the stones and some times laser is also used to break the stone.
4. Laparoscopic/ Robotic Surgery:
During laparoscopic/ Robotic surgery, the doctor makes a small incision to insert the endoscopes and small instruments through the body and remove stones.
In rare cases, an open surgery may be performed instead of laparoscopy.
Treatment depends upon the clinical presentation.
FAQs
1. What are the best treatment options for kidney stones?
Drinking 1.8 to 3.6 litres of water a day helps keep the urine diluted and prevent kidney stones from forming.
Medical therapy: Your doctor may prescribe medications to help pass the kidney stone. This type of medication is known as an alpha blocker and helps relax muscles and pass the kidney stone with less pain.
If the kidney stones are too large, the treatment options may include percutaneous nephrolithotomy, ureteroscopy or extracorporeal shock wave lithotripsy (ESWL).
2. What are the top 5 foods that cause kidney stones?
It is important to be mindful of foods that can potentially lead to the formation of kidney stones in some people:
3. What helps dissolve kidney stones fast?
Staying hydrated helps pass the kidney stones faster. Fluids like lemon juice and apple cider vinegar also help dissolve kidney stones, making them easier to pass.
4. What does kidney stone pain feel like?
If a kidney stone becomes lodged in the ureters, it blocks the flow of urine. It also causes the ureter to spasm and the kidney to swell, which can be very painful. An individual with kidney stones may experience severe or sharp pain in the sides and back, below the ribs or pain that radiates to the groin and lower abdomen.
5. Which fruits are best for kidney stones?
Citrate in fruits inhibits kidney stone formation by binding to calcium. Lime and lemon have been proven to be the best source of citrate, followed by oranges and grapefruits. Additionally, adding cranberries, a natural diuretic to your diet helps mitigate the risk of kidney stones.
Article By Dr. Varun Mittal
Head - Kidney Transplant & Associate Chief - Uro-Oncology & Robotic Surgery (Unit I)
Artemis Hospitals