Urological Stones

Definition/diagnostic criteria Urological stones are crystalline mineral formations within the urinary tract. They form when urine becomes concentrated, leading to the crystallisation of minerals. They may be located in the kidney (nephrolithiasis), ureter (ureterolithiasis), or bladder (cystolithiasis).

Epidemiology In the UK, urological stones affect approximately 10-15% of the population during their lifetime, with a male to female ratio of 3:1. The age range most affected is 30-60 years.

Key risk factors include dehydration, family and previous stone history, gastrointestinal conditions (e.g. Crohn’s disease), some medications (e.g. protease inhibitors) and certain metabolic disorders.

Diagnosis

Clinical features: Symptoms include acute, severe pain (renal colic), typically in the flank region, radiating to the groin, along with haematuria, dysuria, nausea, and vomiting. There may be signs of a urinary tract infection or sepsis.

Investigations

• Urinalysis may show haematuria or signs of co-existent infection.
• Urgent CT KUB is usually required for stone detection.
• Ultrasound is an alternative for pregnant women and children.
• Blood testing (serum calcium) and stone analysis are recommended to allow the diagnosis of treatable conditions, such as cystinuria, uric acid stones, and primary hyperparathyroidism.
• All children and young people with renal or ureteric stones should be assessed with metabolic investigations by a paediatric nephrologist

Treatment Immediate hospital admission should be arranged if:

• The person is in shock or has signs of systemic infection.
• The person is at increased risk of acute kidney injury e.g. if they have pre-existing chronic kidney disease, or if bilateral obstructing stones are suspected.
• The person is dehydrated and cannot take oral fluids due to nausea and/or vomiting.
• There is uncertainty about the diagnosis.

For all other people with suspected renal or ureteric colic:

• Urgent (within 24 hours of presentation) imaging should be offered
• A nonsteroidal anti-inflammatory drug (NSAID) by any route should be offered for pain relief. An opioid analgesic is an alternative if an NSAID is contraindicated.

Management depends on factors such as the size of the stone, severity of symptoms, location of the stone, the age of the person, and any relevant contraindications or comorbidities. Management options include:

Conservative management: Hydration and pain management for certain small stones (<5mm).

Medical expulsive therapy (MET): This involves the use of an alpha-blocker to facilitate spontaneous stone passage during the observation period. It is considered for people with distal ureteric stones less than 10 mm.

Surgical treatment: Options include: shockwave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL) and ureteroscopy.

Behavioural modifications to reduce the risk of recurrence:  Advice includes increasing fluid intake, adding fresh lemon juice to drinking water, avoiding carbonated drinks, reducing salt intake, maintaining a normal dietary calcium intake, eating a balanced diet, and maintaining a healthy weight.

Prognosis Recurrence rates can be up to 50% within ten years. Preventative measures include lifestyle and dietary modifications and, in certain cases, pharmacotherapy for underlying metabolic issues.