Kidney Stones

Kidney stones are hard deposits of minerals and salts that form inside your kidneys. These stones can affect any part of your urinary tract from your kidneys to your bladder. Often described as one of the most painful medical conditions, kidney stones affect about 1 in 11 people at some point in their lives, with increasing prevalence due to dietary and lifestyle factors.

⚠️ Medical Emergency

Seek immediate medical care if experiencing: severe pain with fever and chills, blood in urine with nausea and vomiting, difficulty urinating or complete blockage, or signs of infection. These may indicate serious complications requiring emergency treatment.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of any medical condition.

Types of Kidney Stones

Calcium Stones (80%)

  • Calcium oxalate: Most common type
    • Forms when calcium combines with oxalate
    • Associated with high oxalate foods
    • Dehydration increases risk
  • Calcium phosphate: Less common
    • Associated with metabolic conditions
    • More common in alkaline urine
    • Linked to renal tubular acidosis

Struvite Stones (10%)

  • Form in response to urinary tract infections
  • Can grow quickly and become large
  • More common in women
  • Also called "infection stones"
  • May form staghorn calculi

Uric Acid Stones (5-10%)

  • Form when urine is too acidic
  • More common in men
  • Associated with:
    • High-protein diets
    • Gout
    • Chronic diarrhea
    • Diabetes

Cystine Stones (<1%)

  • Caused by hereditary disorder (cystinuria)
  • Form in people who excrete too much cystine
  • Often recurrent
  • Start forming in childhood

Symptoms

Small stones may pass without symptoms, but larger stones typically cause:

Classic Renal Colic

  • Severe pain:
    • Comes in waves and fluctuates in intensity
    • Located in side and back, below ribs
    • Radiates to lower abdomen and groin
    • Changes location as stone moves
    • Described as excruciating
  • Pain characteristics:
    • Sudden onset
    • Colicky (comes and goes)
    • May last minutes to hours
    • Not relieved by position changes

Associated Symptoms

  • Urinary symptoms:
    • Pink, red, or brown urine (hematuria)
    • Cloudy or foul-smelling urine
    • Persistent urge to urinate
    • Urinating in small amounts
    • Burning sensation during urination
  • Systemic symptoms:
    • Nausea and vomiting
    • Fever and chills (if infection present)
    • Restlessness and inability to find comfortable position

Location-Specific Symptoms

  • Kidney (renal pelvis): Flank pain
  • Upper ureter: Flank pain radiating to abdomen
  • Mid ureter: Pain radiating to lower abdomen
  • Lower ureter: Pain radiating to groin/genitals
  • Bladder: Suprapubic pain, urgency

Causes and Risk Factors

Formation Process

Kidney stones form when urine contains more crystal-forming substances than the fluid can dilute. Factors include:

  • Supersaturation of minerals
  • Lack of stone inhibitors
  • Urine stasis
  • Crystal nucleation and growth

Major Risk Factors

  • Dehydration:
    • Insufficient fluid intake
    • Hot climate or excessive sweating
    • Concentrated urine
  • Diet:
    • High sodium intake
    • High animal protein
    • High oxalate foods (spinach, nuts, chocolate)
    • Low calcium intake (paradoxically)
    • High sugar consumption
  • Medical conditions:
    • Hyperparathyroidism
    • Renal tubular acidosis
    • Urinary tract infections
    • Cystinuria
    • Inflammatory bowel disease
    • Chronic diarrhea
    • Gout
  • Medications:
    • Calcium supplements (excessive)
    • Vitamin C (high doses)
    • Diuretics
    • Antacids
    • Certain antibiotics

Demographics

  • Gender: Men 2-3x more likely until age 50
  • Age: Peak incidence 30-50 years
  • Geography: Higher in hot climates
  • Family history: 2.5x increased risk
  • Previous stones: 50% recurrence within 5 years

Diagnosis

Imaging Studies

  • CT scan (non-contrast):
    • Gold standard for diagnosis
    • Detects all stone types
    • Shows size, location, and obstruction
    • Quick and accurate
  • Ultrasound:
    • First choice in pregnancy
    • No radiation exposure
    • Good for hydronephrosis
    • May miss small stones
  • KUB X-ray:
    • Shows calcium-containing stones
    • Misses uric acid stones
    • Used for follow-up
  • IVP (rarely used):
    • Shows urinary system function
    • Requires contrast dye

Laboratory Tests

  • Urinalysis:
    • Blood (hematuria)
    • Crystals
    • pH level
    • Signs of infection
  • Blood tests:
    • Creatinine (kidney function)
    • Calcium levels
    • Uric acid
    • Electrolytes
    • Parathyroid hormone
  • 24-hour urine collection:
    • For recurrent stones
    • Measures stone-forming substances
    • Guides prevention
  • Stone analysis:
    • Determines composition
    • Guides treatment and prevention

Treatment Options

Conservative Management (Stones <5mm)

  • Medical expulsive therapy:
    • Alpha blockers (tamsulosin)
    • Calcium channel blockers
    • Increases passage rate
  • Pain management:
    • NSAIDs (first line)
    • Opioids for severe pain
    • Antispasmodics
  • Supportive care:
    • Increased fluid intake
    • Strain urine to catch stone
    • Activity as tolerated

Active Stone Removal

Extracorporeal Shock Wave Lithotripsy (ESWL)

  • Uses sound waves to break stones
  • Non-invasive outpatient procedure
  • Best for stones <2cm in kidney
  • Success rate: 70-90%
  • May require multiple sessions

Ureteroscopy (URS)

  • Scope inserted through urethra
  • Direct stone removal or laser fragmentation
  • High success rate (>90%)
  • Good for ureteral stones
  • Usually requires stent placement

Percutaneous Nephrolithotomy (PCNL)

  • For large stones (>2cm)
  • Direct kidney access through back
  • Requires hospitalization
  • Highest success rate for large stones

Medical Dissolution

  • Uric acid stones:
    • Alkalinization with potassium citrate
    • Allopurinol for high uric acid
    • Can dissolve existing stones
  • Cystine stones:
    • Alkalinization
    • Tiopronin or penicillamine
    • High fluid intake essential

Prevention Strategies

Hydration

  • Drink 2.5-3 liters of water daily
  • Urine should be pale yellow
  • Increase in hot weather or exercise
  • Distribute throughout the day
  • Include citrus beverages (lemonade)

Dietary Modifications

General Guidelines

  • Reduce sodium: <2,300mg/day
  • Moderate protein: 0.8-1g/kg body weight
  • Adequate calcium: 1,000-1,200mg/day from food
  • Limit oxalate: If calcium oxalate stones

Stone-Specific Diet

  • Calcium oxalate:
    • Pair high-oxalate foods with calcium
    • Limit spinach, nuts, chocolate, beets
    • Avoid vitamin C supplements
  • Uric acid:
    • Limit animal protein
    • Reduce purines (organ meats, anchovies)
    • Increase fruits and vegetables
  • Struvite:
    • Prevent UTIs
    • Complete antibiotic courses

Medications for Prevention

  • Thiazide diuretics: Reduce calcium excretion
  • Potassium citrate: Alkalinizes urine
  • Allopurinol: For uric acid stones
  • Acetohydroxamic acid: For struvite stones

Lifestyle Factors

  • Maintain healthy weight
  • Regular physical activity
  • Avoid crash diets
  • Manage underlying conditions
  • Regular follow-up for stone formers

Potential Complications

  • Obstruction: Blocked urine flow
  • Hydronephrosis: Kidney swelling
  • Infection: UTI or pyelonephritis
  • Urosepsis: Life-threatening infection
  • Chronic kidney disease: From recurrent stones
  • Kidney damage: Scarring and loss of function
  • Stricture formation: Ureteral narrowing

Prognosis and Recurrence

Most kidney stones pass spontaneously or can be successfully treated:

  • Stones <5mm: 90% pass spontaneously
  • Stones 5-10mm: 50% pass spontaneously
  • Stones >10mm: Usually require intervention

Recurrence Rates

  • 50% within 5 years without prevention
  • 10-15% with proper prevention
  • Higher in metabolic disorders
  • Varies by stone type

With proper treatment and prevention strategies, most people can effectively manage kidney stones and significantly reduce recurrence risk. Early intervention and lifestyle modifications are key to preventing complications and maintaining kidney health.