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.
What are the Different 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.
What Causes Kidney Stones?
Kidney stones are hard deposits made of minerals and salts that form inside your kidneys when your urine becomes overly concentrated. This concentration allows minerals to crystallize and stick together, creating "stones" that can range from the size of a grain of sand to a golf ball.
- Dehydration: Not drinking enough water is the most common cause. When fluid intake is low, minerals like calcium and oxalate are more likely to settle and clump together in the urinary tract.
- Dietary Choices: Diets high in protein, sodium (salt), and sugar can increase the risk. High sodium, in particular, increases the amount of calcium your kidneys must filter, significantly raising stone risk.
- Oxalate-Rich Foods: Consuming large amounts of foods high in oxalates—such as spinach, beets, nuts, and chocolate—can lead to the formation of calcium-oxalate stones, the most common type.
- Obesity and Weight: A high Body Mass Index (BMI), large waist size, and weight gain have been linked to an increased risk of stone formation.
- Medical Conditions & Genetics: Conditions like hyperparathyroidism, urinary tract infections (UTIs), and inflammatory bowel diseases (like Crohn's) can change how your body processes minerals. Additionally, a family history of stones makes you more susceptible.
- Certain Supplements and Medications: Overusing Vitamin C supplements, certain laxatives, and calcium-based antacids can contribute to mineral buildup in the kidneys.
Common Symptoms of Kidney Stones
Kidney stones are often "silent" until they begin to move within the kidney or pass into the ureter (the tube connecting the kidney and bladder). Once displaced, they can cause significant discomfort, typically characterized by:
- Severe, Sharp Pain: Often felt in the side and back, below the ribs (renal colic). This pain may radiate to the lower abdomen and groin.
- Fluctuating Intensity: The pain often comes in waves and can shift in intensity as the stone moves through the urinary tract.
- Changes in Urination: You may experience a persistent urge to urinate, urinating more often than usual, or a burning sensation during the process.
- Discolored Urine: Urine may appear pink, red, or brown (indicating blood) or look cloudy and have an unpleasant odor
- Nausea and Vomiting: Severe pain often triggers upset stomach or physical sickness.
- Fever and Chills: If these symptoms are present, it may indicate an underlying infection, which requires immediate medical attention.
When is the Risk of Kidney Stones Higher?
While anyone can develop a kidney stone, certain factors and life stages significantly elevate the risk:
- Low Fluid Intake: People who live in warm, dry climates or sweat excessively without replacing fluids are at a much higher risk due to concentrated urine.
- Family or Personal History: If a close relative has had stones, or if you have already had one, your probability of developing another is statistically higher.
- High-Sodium & Protein Diets: Consuming excessive salt forces the kidneys to excrete more calcium, while high animal protein levels can increase uric acid and decrease citrate (which helps prevent stones).
- Digestive Diseases and Surgery: Gastric bypass surgery, inflammatory bowel disease (IBD), or chronic diarrhea can alter the digestive process, affecting your absorption of calcium and water.
- Metabolic Syndromes: Conditions like Type 2 diabetes, high blood pressure, and obesity change the chemical composition of urine, making stone formation more likely.
- Structural Abnormalities: Being born with irregularly shaped kidneys or narrowed ureters can lead to urine stagnation, providing a "breeding ground" for crystal growth.
Which Tests Diagnose Kidney Stones?
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.
- Urine test: This test detects signs of infection and stone-forming crystals in the urine.
- Blood tests:This test detects infection, high levels of calcium, uric acid, phosphorus, and assess kidney function.
- Imaging tests: An ultrasound, CT scans and X-rays helps detect the shape, size, location and number of stones.
- 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.
- 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.
What Are the Treatment Options for Kidney Stones?
The treatment for kidney stones depends on:
- The size of the kidney stone
- Type of stone
- Location of the stone
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 percutaneous nephrolithotomy. During this procedure, an ultrasound probe breaks and removes the stones and sometimes a 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.
Article by Dr. Dinesh Bansal
Chief Nephrology (Unit III)
Artemis Hospitals
