Kidney Stones
Also known as Renal calculi, Nephrolithiasis
This article is general health information for the selected condition. It is not a diagnosis and does not replace clinical judgement. If you have questions or need treatment advice, please consult a qualified healthcare professional.
What is kidney stones?
Kidney stones are hard deposits of minerals and salts that form inside the kidneys. Pain occurs when a stone moves into the ureter and obstructs urine flow, producing one of the most severe pains encountered in medicine. Most small stones pass spontaneously, and increasing fluid intake is the single most effective way to prevent recurrence.
Causes
- Calcium oxalate stones, the most common type
- Uric acid stones associated with gout
- Struvite stones related to urinary infection
- Cystine stones from an inherited disorder
- Concentrated urine from low fluid intake
Symptoms
- Severe colicky pain in the flank radiating to the groin
- Restlessness and inability to find a comfortable position
- Blood in the urine
- Nausea and vomiting
- Urinary urgency and frequency
- Fever and chills if infection develops
Risk factors
- Low fluid intake and hot climates
- High salt and animal protein intake
- Obesity
- Previous kidney stone
- Family history
- Gout and hyperparathyroidism
- Some medicines and bowel disease
Diagnosis
- Non contrast CT of the kidneys, ureters and bladder
- Ultrasound, preferred in pregnancy and children
- Urinalysis for blood and infection
- Blood tests for kidney function and calcium
- Stone analysis when a stone is retrieved
- Metabolic evaluation for recurrent stone formers
Treatment
- Strong analgesia, with nonsteroidal anti inflammatory drugs often most effective
- Generous fluid intake
- Medical expulsive therapy such as tamsulosin for selected ureteric stones
- Extracorporeal shock wave lithotripsy
- Ureteroscopy with laser fragmentation
- Percutaneous nephrolithotomy for large stones
- Urgent decompression if obstruction occurs with infection
Self care
- Drink enough to pass at least 2 to 2.5 litres of urine daily
- Take prescribed pain relief promptly during an attack
- Strain urine if asked, to catch the stone for analysis
- Keep active, which may help small stones pass
- Reduce salt intake
- Do not restrict dietary calcium
- Limit oxalate rich foods only if advised after stone analysis
When to see a doctor
Book an appointment if:
- Recurrent stones
- Pain not controlled with prescribed analgesia
- Blood in the urine
- A stone that has not passed after several weeks
- Family history with symptoms
- To arrange metabolic testing after repeated stones
Some symptoms need emergency care rather than an appointment. See the warning signs listed above.
Prevention
- Drink generously throughout the day, which is the strongest measure
- Reduce dietary salt
- Keep normal dietary calcium intake
- Limit animal protein excess
- Maintain a healthy weight
- Take preventive medication if advised after stone analysis
Outlook
Most stones under 5 millimetres pass spontaneously within a few weeks. Larger stones often need lithotripsy or ureteroscopy, both highly effective. Recurrence is common, with around half of people forming another stone within ten years, which is why fluid intake and metabolic assessment matter after a first episode.
Common questions
When is a kidney stone an emergency?
Fever with stone pain suggests an obstructed infected kidney, which is a urological emergency requiring urgent drainage. Uncontrolled pain, persistent vomiting or a single functioning kidney also need urgent care.
Should calcium be avoided to prevent stones?
No. Restricting dietary calcium increases oxalate absorption and can make stones more likely. Normal dietary calcium with reduced salt and generous fluids is the recommended approach.
How much fluid prevents recurrence?
Enough to produce at least 2 to 2.5 litres of urine daily, which usually means drinking around 2.5 to 3 litres. This is the best evidenced single preventive measure.
References
Important: Dard AI is not a medical device and does not diagnose, treat, or replace clinician judgement. This article is general information only. Always consult a qualified healthcare professional about diagnosis and treatment, and seek emergency care for severe or rapidly worsening symptoms.