Renal stones (Nephrolithiasis)

Background

• Nephrolithiasis describes the formation of all types of urinary stones (calculi) in the kidney
• Renal stones are formed secondary to substance precipitation affecting the kidney and the ureter
• Risk factors include: dehydration and high sodium, hyperuricemia and low potassium diets
• Renal stones are more common in men

Risk factors

• Hyperparathyroidism
• Hypocitraturia
• Hyperoxaluria
• Indwelling catheter
• Urinary tract infections
• Malabsorption (eg, Crohn’s disease)
• Low fluid intake

Clinical features

• Colicky flank pain radiating to groin or lower abdomen
• Dysuria
• Urgency and frequency
• Hematuria
• Unilateral flank/ lower abdominal tenderness
• Costovertebral angle (CVA) tenderness

Diagnosis

Imaging

• Renal ultrasound (in patients who are pregnant and children)
• Non-contrast computerised tomography (CT)

Labs

• Serum: creatinine, Uric acid and ionized calcium
• Urinalysis/dipstick (urine pH)
• Stone composition analysis

Differential diagnosis

• Urinary tract infections
• Acute pyelonephritis
• Hernia

Treatment

Medical treatment

• Analgesia, bed rest, and intravenous fluids (first line in uncomplicated nephrolithiasis < 10 mm)
• Alpha blockers or calcium channel blockers (relaxes the ureter)

Surgical treatment

• Extracorporeal shock wave lithotripsy (preferred for renal stones < 2 cm - Percutaneous nephrolithotomy (preferred for renal > 2 cm)

Complications

• Ureteral obstruction
• Ureteral stricture
• Hydronephrosis
• Urinary tract infection
• Pyelonephritis
• Renal deterioration

Supplementary tables

• Table 1: Content, pH and imaging findings for primary renal stones

• Table 2: Stone type, urine crystal and notes

• Table 3: Dietary interventions for calcium stones