Urolithiasis- Management

Urolithiasis refers to the formation of calculi (stones) within any part of the urinary tract, including the kidneys, ureters, bladder, and urethra. Kidney stones develop when urine becomes supersaturated with stone-forming salts, resulting in crystal formation, aggregation, and eventual stone growth.

Urinary stones are composed of different substances, most commonly calcium oxalate, calcium phosphate, uric acid, struvite, and cystine. The clinical presentation depends on the size, location, degree of obstruction, and presence of infection.

Urolithiasis is an important urological condition because it may cause urinary obstruction, infection, renal impairment, and recurrent stone formation. Patients with kidney stones have an increased risk of chronic kidney disease, end-stage kidney failure, and cardiovascular disease.

Epidemiology

Urolithiasis affects individuals worldwide and is more common among adults, particularly males. The incidence varies according to geographical location, climate, dietary habits, and genetic predisposition.

Stone disease commonly affects individuals between 30 and 60 years of age and has a tendency to recur, especially in patients with underlying metabolic abnormalities or inadequate preventive measures.

Risk factors

Dietary and lifestyle factors

• Low fluid intake

• High intake of animal protein

• High salt intake

• Excessive intake of oxalate-rich foods

• Excessive vitamin C supplementation

• Low intake of fruits and vegetables

• Obesity

• Sedentary lifestyle

Medical conditions

• Hyperparathyroidism

• Gout

• Hyperuricaemia

• Chronic diarrhoeal diseases

• Malabsorption syndromes

• Renal tubular disorders

• Recurrent urinary tract infections

• Metabolic abnormalities causing hypercalciuria or hyperoxaluria

Urinary tract-related factors

• Urinary obstruction

• Congenital urinary tract abnormalities

• Neurogenic bladder

• Previous urinary stones

Pathophysiology

Urolithiasis occurs when urine becomes supersaturated with stone-forming substances, allowing crystal formation and aggregation.

The process involves:

1. Increased concentration of stone-forming salts in urine.

2. Formation of crystals within the urinary tract.

3. Growth and aggregation of crystals into stones.

4. Migration of stones through the urinary tract.

Stone formation is influenced by:

• Urinary concentration of calcium, oxalate, uric acid, phosphate, and cystine.

• Reduced urinary inhibitors of stone formation such as citrate.

• Urinary pH.

• Presence of infection-producing organisms.

As stones pass through the ureter, they may cause obstruction and increased pressure within the urinary tract, resulting in renal colic and possible hydronephrosis.

Clinical presentation

Clinical features depend on the size and location of the stone. Small stones may remain asymptomatic, whereas stones causing obstruction typically present with acute pain.

Symptoms

• Sudden onset severe colicky flank pain

• Pain radiating to the groin

• Pain radiating to the scrotum in males or labium in females

• Nausea and vomiting

• Haematuria

• Restlessness due to severe pain

• Urinary frequency or urgency when the stone reaches the lower ureter

• Dysuria if associated with infection

Clinical signs

• Patient unable to remain still due to severe colicky pain

• Sweating

• Pallor

• Flank tenderness

• Costovertebral angle tenderness

• Signs of urinary obstruction

• Fever and systemic signs if infection is present

Diagnostic criteria

Diagnosis of urolithiasis is based on:

• Clinical features suggestive of renal colic.

• Evidence of urinary tract stones on imaging.

• Laboratory evidence of haematuria or infection.

Features supporting diagnosis include:

• Acute colicky flank pain

• Microscopic or visible haematuria

• Imaging evidence of urinary calculi

• Evidence of urinary obstruction such as hydronephrosis or hydroureter

Investigations

Urinalysis

Includes:

• Dipstick examination

• Urine biochemistry

• Urine microscopy

Findings may include:

• Microscopic haematuria

• Crystals

• Features of urinary tract infection

Imaging investigations

Non-contrast CT scan of kidney, ureter, and bladder (CT KUB)

• Gold standard investigation for diagnosis of urinary stones.

• Determines stone size, location, and degree of obstruction.

Ultrasonography of kidney, ureter, and bladder (KUB)

Used to assess:

• Hydronephrosis

• Hydroureter

• Obstruction

• Presence of stones

Plain abdominal X-ray

• Detects up to 90% of calculi because many urinary stones are radio-opaque.

Intravenous urography or CT urography

• Confirms upper urinary tract lithiasis where indicated.

Stone analysis

Chemical composition of the stone is the most valuable investigation for guiding prevention strategies.

Metabolic evaluation

First stone episode

Investigations include:

• Serum calcium

• Serum magnesium

• Serum phosphate

• Serum uric acid

• Serum urea

• Serum potassium

• Serum sodium

• Serum chloride

• Serum bicarbonate

Recurrent stones

Additional investigations include:

• Parathyroid hormone level

• Urine dipstick and biochemical analysis

• 24-hour urine collection for:

  • Urea

  • Creatinine clearance

  • Sodium

  • Calcium

  • Oxalate

  • Uric acid

Management

Management depends on:

• Stone size

• Stone location

• Degree of obstruction

• Presence of infection

• Kidney function

• Symptoms severity

The objectives of treatment are:

• Relief of pain.

• Removal or spontaneous passage of stones.

• Treatment of obstruction or infection.

• Prevention of recurrence.

Non-pharmacological treatment

General prevention for all stones

• Increase fluid intake to achieve urine output of at least 2 litres per day.

Hyperoxaluria

• Reduce oxalate-rich foods.

• Increase dietary calcium intake.

• Limit vitamin C supplementation.

Calcium stones

• Reduce dietary salt intake.

• Restrict excessive animal protein intake including meat, fish, and poultry.

• Increase fruit and vegetable intake.

Calcium oxalate, cystine, and uric acid stones

• Diet rich in fruits and vegetables.

• Use citrate supplementation where indicated.

Uric acid stones

• Control gout and hyperuricaemia.

Calcium phosphate and struvite stones

• Acidify urine where appropriate.

Surgical and procedural treatment

Intervention is indicated in patients with:

• Obstructive uropathy

• Infection associated with obstruction

• Persistent pain despite medical treatment

• Failure of spontaneous stone passage

• Solitary kidney requiring urgent intervention

Emergency decompression may be required using:

• Percutaneous nephrostomy

• Ureteric double-J (DJ) stenting

Stone removal or fragmentation procedures include:

• Ureteroscopy with stone fragmentation

• Percutaneous nephrolithotomy

• Extracorporeal shock wave lithotripsy (ESWL)

Pharmacological treatment

Analgesia for renal colic

Non-steroidal anti-inflammatory drugs

• Ibuprofen 400 mg orally every 8 hours for 3 days.

OR

• Diclofenac 75 mg intramuscularly as a stat dose, followed by 50 mg orally every 8 hours.

Opioid analgesics

For severe pain:

• Tramadol 100 mg intravenously as a stat dose, followed by 50 mg orally every 8 hours.

OR

• Pethidine 100 mg intramuscularly as a stat dose.

Supportive treatment

Additional treatment may include:

• Antiemetics for nausea and vomiting.

• Intravenous fluids where clinically indicated.

Medical expulsive therapy

For distal ureteric calculi less than 7 mm:

• Tamsulosin 0.4 mg orally once daily for one month.

OR

• Nifedipine 10 mg orally once daily for 30 days.

Blood pressure should be monitored when nifedipine is used.

Prevention of recurrent stones

Calcium stones

Thiazide diuretics may be used:

• Bendrofluazide 5 mg orally once daily.

OR

• Hydrochlorothiazide 12.5–50 mg orally once daily.

Low uric acid levels

• Allopurinol 50–100 mg orally once daily.

Management according to underlying cause

Hypercalciuria

• Reduce dietary salt intake.

• Consider thiazide diuretic therapy.

• Monitor calcium levels.

Hyperoxaluria

• Dietary oxalate restriction.

• Adequate calcium intake.

• Limit vitamin C supplementation.

Gout-associated uric acid stones

• Control serum uric acid levels.

• Use allopurinol where indicated.

Infection-related stones (struvite)

• Treat urinary infection.

• Remove infected stones.

• Correct urinary obstruction.

Referral

Refer patients for specialist urological care if:

• Obstructive uropathy is present.

• Infection is associated with obstruction.

• Solitary kidney with obstruction.

• Persistent renal colic despite analgesia.

• Large stones unlikely to pass spontaneously.

• Recurrent stones requiring metabolic evaluation.

• Reduced kidney function.

• Need for surgical intervention.

Complications

• Hydronephrosis

• Hydroureter

• Urinary tract infection

• Pyelonephritis

• Urosepsis

• Acute kidney injury

• Chronic kidney disease

• Urinary obstruction

• Recurrent stone formation

• Loss of renal function

Prognosis

The prognosis depends on stone size, location, presence of obstruction, infection, and underlying metabolic abnormalities.

Most small ureteric stones pass spontaneously with conservative treatment. However, untreated obstructing stones, especially when associated with infection, may result in serious complications including renal damage and sepsis.

Recurrence is common; therefore, preventive strategies and metabolic evaluation are important, particularly in recurrent stone disease.

Prevention

• Maintain adequate fluid intake to produce at least 2 litres of urine daily.

• Maintain a balanced diet rich in fruits and vegetables.

• Reduce excessive salt intake.

• Avoid excessive animal protein consumption.

• Limit unnecessary vitamin C supplementation.

• Maintain healthy body weight.

• Control gout and metabolic disorders.

• Treat urinary tract infections promptly.

• Follow preventive therapy according to stone composition.