Understanding Kidney Stones (Renal Stones)

Kidney stones, also known as renal stones or nephrolithiasis, are hard deposits made of minerals and salts that form inside your kidneys. They can vary in size, from as small as a grain of sand to as large as a golf ball. While they often go unnoticed if they’re small, larger stones can cause immense pain and complications as they move through the urinary tract.

How Do Kidney Stones Form?

Kidney stones form when your urine contains more crystal-forming substances—such as calcium, oxalate, and uric acid—than the fluid in your urine can dilute. At the same time, your urine may lack substances that prevent crystals from sticking together, creating an ideal environment for stone formation.

Types of Kidney Stones

There are four main types of kidney stones:

1. Calcium Stones: These are the most common type, usually in the form of calcium oxalate. Oxalate is a substance found naturally in many foods, and a high intake of certain fruits, vegetables, nuts, and chocolate can contribute to their formation.
2. Struvite Stones: These stones often form in response to a urinary tract infection (UTI). They can grow quickly and become quite large, sometimes with few symptoms, which can make them difficult to detect early.
3. Uric Acid Stones: These stones can form in people who don’t drink enough fluids or have a diet high in protein. They are also common in people with gout.
4. Cystine Stones: This is a rare type of stone that forms in individuals with a hereditary disorder called cystinuria, which causes the kidneys to excrete large amounts of a specific amino acid.

Symptoms of Kidney Stones

The signs and symptoms of kidney stones can vary depending on the size and location of the stone. You might not have any symptoms until the stone begins to move down your ureter (the tube connecting the kidney and bladder).

Common symptoms include:

• Severe pain in the side and back, below the ribs.
• Pain that spreads to the lower abdomen and groin.
• Pain that comes in waves and fluctuates in intensity.
• Pain during urination.
• Pink, red, or brown blood in the urine (hematuria).
• Cloudy or foul-smelling urine.
• A persistent need to urinate, or urinating more often than usual.
• Nausea and vomiting.
• Fever and chills if an infection is present.

Risk Factors for Kidney Stones

Several factors can increase your risk of developing kidney stones:

• Dehydration: Not drinking enough water is a major risk factor.
• Diet: A diet high in protein, salt, and sugar can increase your risk.
• Obesity: A high body mass index (BMI), large waist size, and weight gain are linked to a higher risk.
• Digestive diseases and surgery: Gastric bypass surgery, inflammatory bowel disease, or chronic diarrhea can alter the absorption of calcium and water.
• Family history: Having a family member with kidney stones increases your likelihood of getting them.
• Certain medical conditions: Gout, urinary tract infections, and hyperparathyroidism can increase the risk.

Diagnosis

Diagnosing kidney stones is a multi-step process that combines physical examination with imaging and laboratory tests to confirm the presence of stones and identify their type. A doctor will typically start by taking a detailed medical history and conducting a physical exam to understand the patient’s symptoms, which often include severe, sharp pain in the side or back, blood in the urine, and nausea. The most common and accurate diagnostic tool is a CT scan of the abdomen and pelvis, which can precisely locate the stone, determine its size, and assess if it is causing a blockage. Ultrasound is another valuable imaging technique, especially for children and pregnant women, as it is non-invasive and does not use radiation. A 24-hour urine collection is often used to measure the levels of stone-forming substances and help the doctor formulate a plan to prevent future stones, while a blood test can reveal elevated levels of minerals like calcium and uric acid. Finally, if the patient passes a stone, it is often collected and sent to a lab for stone analysis to determine its chemical composition, which is critical for guiding future preventive measures.