Kidney Stones – Causes, Symptoms and Treatment

What Are Kidney Stones?

Kidney stones (medically known as nephrolithiasis or urolithiasis) are solid mineral deposits that form when certain substances in the urine become highly concentrated and crystallize inside the kidneys. They can range in size from a tiny grain of sand to several centimeters in diameter. Kidney stones are among the most common disorders of the urinary tract and affect millions of people worldwide.

Causes and Risk Factors

Kidney stones typically develop due to an imbalance of substances dissolved in the urine. The following factors can increase the risk of stone formation:

• Insufficient fluid intake: Concentrated urine promotes crystallization of minerals.
• Diet: High intake of salt, animal protein, and oxalate-rich foods (e.g., spinach, nuts).
• Metabolic disorders: Conditions such as hyperparathyroidism, gout, or certain kidney diseases.
• Genetic predisposition: A family history of kidney stones increases risk.
• Certain medications: Some drugs can promote stone formation as a side effect.
• Urinary tract infections: Bacterial infections can lead to the formation of struvite stones.

Types of Kidney Stones

Kidney stones are classified by their chemical composition:

• Calcium oxalate stones: The most common type, accounting for approximately 70-80% of all cases.
• Calcium phosphate stones: Often associated with metabolic disorders.
• Uric acid stones: Form when uric acid levels in the blood or urine are elevated, as in gout.
• Struvite stones: Caused by urinary tract infections with specific bacteria.
• Cystine stones: Rare; caused by a hereditary metabolic disorder affecting amino acid transport.

Symptoms

Small kidney stones may pass unnoticed, while larger stones or those that enter the ureter can cause significant symptoms:

• Renal colic: Sudden, intense, wave-like pain in the flank or back, often radiating to the groin or lower abdomen.
• Blood in the urine (hematuria): Urine may appear pink, red, or brown.
• Nausea and vomiting
• Frequent urge to urinate and a burning sensation during urination.
• Fever and chills: These may indicate a concurrent infection, which is a medical emergency.

Diagnosis

Several diagnostic methods are used to detect and assess kidney stones:

• Ultrasound: A first-line, radiation-free imaging method for detecting stones in the kidneys.
• CT scan (computed tomography): The gold standard for precisely locating stones and determining their size.
• Urine analysis: Detects blood, crystals, or signs of infection in the urine.
• Blood tests: Assess kidney function and levels of calcium, uric acid, and other relevant markers.
• X-ray: Useful for detecting calcium-containing stones.

Treatment

Conservative Management

Small stones (generally under 5 mm) often pass spontaneously with adequate hydration (2-3 liters of water per day). Pain relievers and antispasmodic medications help manage discomfort. Alpha-blockers may be prescribed to facilitate the passage of ureteral stones.

Extracorporeal Shock Wave Lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy is a non-invasive procedure that uses focused sound waves from outside the body to break kidney stones into smaller fragments that can then be passed naturally through the urine. It is commonly used for medium-sized stones.

Endoscopic Procedures

For larger stones or when other treatments are not effective, endoscopic procedures such as ureteroscopy (URS) may be performed. A thin flexible instrument is passed through the urethra to reach the stone, which is then fragmented using a laser.

Surgical Treatment

Very large or complex stones may require percutaneous nephrolithotomy (PCNL), in which the stone is removed through a small incision in the back. Open surgery is rarely necessary today.

Prevention

The following measures can help prevent kidney stones or reduce the risk of recurrence:

• Drink sufficient fluids daily (at least 2-2.5 liters, preferably water or unsweetened herbal teas).
• Follow a balanced, low-salt diet with moderate consumption of animal protein.
• Reduce intake of oxalate-rich foods if calcium oxalate stones have been diagnosed.
• Attend regular urological check-ups if you are at increased risk.
• Treat any underlying metabolic conditions appropriately.

References

1. Türk C. et al.: EAU Guidelines on Urolithiasis. European Association of Urology (2023). Available at: https://uroweb.org/guidelines/urolithiasis
2. Scales C. D. et al.: Prevalence of Kidney Stones in the United States. European Urology, 2012;62(1):160-165.
3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): Kidney Stones. U.S. Department of Health and Human Services (2023). Available at: https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones