Kidney stones (renal calculi or nephrolithiasis) affect around 1 in 10 people in the UK over their lifetime. They cause some of the most severe pain known to medicine — often described as worse than childbirth — and send approximately 60,000 people to A&E every year. Fortunately, most small kidney stones pass on their own with pain relief, and larger stones can be treated with non-invasive procedures. Understanding what causes kidney stones can help prevent recurrence.
Kidney Stone Symptoms
A stone that remains in the kidney may cause no symptoms. It is when a stone moves into the ureter (the tube connecting the kidney to the bladder) that the intense “renal colic” pain begins:
- Severe, cramping pain in the back and side (flank), usually coming in waves — often rated 10/10 by patients
- Pain radiating downwards towards the groin, lower abdomen, and into the testicles/labia as the stone descends
- Nausea and vomiting — pain is so severe it triggers vomiting
- Blood in the urine (haematuria) — visible pink/red urine or microscopic blood on dipstick
- Frequent, urgent urination — especially as the stone approaches the bladder
- Burning urination — similar to a UTI
- Inability to find a comfortable position — unlike the still position preferred in appendicitis
Seek Emergency Care If You Have
- Fever with kidney stone symptoms — suggests kidney infection (obstructive pyelonephritis) — a urological emergency; can become septic rapidly
- Only one kidney and a stone is blocking it — risk of acute kidney injury
- Pain that cannot be controlled with over-the-counter medication
- Vomiting preventing oral medication
Types of Kidney Stones
| Type | % of cases | Key associations |
|---|---|---|
| Calcium oxalate | ~70–80% | Most common; linked to high oxalate diet, low fluid intake, low calcium intake |
| Calcium phosphate | ~5–10% | Associated with hyperparathyroidism and renal tubular acidosis |
| Uric acid | ~5–10% | Associated with gout, high-purine diet, acidic urine; radiolucent on X-ray |
| Struvite (magnesium ammonium phosphate) | ~5–10% | Caused by urease-producing bacteria (e.g., Proteus) during recurrent UTIs; can form “staghorn” calculi |
| Cystine | ~1% | Rare genetic disorder (cystinuria); forms large stones; recurrent from childhood |
Diagnosis
If a kidney stone is suspected, your GP or A&E doctor will typically arrange:
- Urine dipstick — to check for blood, signs of infection, and pH
- Blood tests — FBC, CRP, U&E (kidney function), calcium, uric acid
- CT KUB (non-contrast CT of kidneys, ureters, and bladder) — the gold-standard investigation; detects virtually all stone types; available 24/7 in most UK hospitals; dose-efficient modern scanners are used
- Ultrasound — preferred in children and pregnant women; can detect hydronephrosis (kidney swelling from obstruction) but misses small ureteric stones
- Plain X-ray (KUB) — can show calcium-containing stones; misses uric acid and small stones
NHS Treatment for Kidney Stones
Conservative Management (Small Stones — <5mm)
Approximately 80–90% of stones under 5mm pass spontaneously within 4 weeks. Treatment focuses on:
- Pain relief — NSAIDs (diclofenac suppositories or ibuprofen) are first-line; more effective than opioids for renal colic; given with an anti-emetic (metoclopramide, ondansetron)
- High fluid intake — drink enough to produce at least 2–2.5 litres of urine daily; helps flush the stone
- Medical expulsive therapy (MET) — tamsulosin (an alpha-blocker) relaxes the ureter, helping stones pass; used for stones 5–10mm; particularly effective for lower ureteric stones
- Strain urine — using a coffee filter or purpose-made strainer to catch the stone for analysis (which guides long-term prevention)
ESWL — Extracorporeal Shock Wave Lithotripsy
For stones 5–20mm that haven’t passed. Shock waves are focused on the stone using X-ray or ultrasound guidance, breaking it into fragments small enough to pass. Performed as a day procedure (no general anaesthetic usually required). Multiple sessions may be needed. Success rate is lower for hard calcium oxalate monohydrate and cystine stones.
Ureteroscopy (URS) and Laser Lithotripsy
A flexible ureteroscope is passed through the urethra and bladder into the ureter; a laser (Holmium or Thulium fibre laser) fragments the stone into dust. Done under general anaesthetic; usually a day case. Very high success rates (>90%) for most ureteric stones. A temporary ureteric stent may be left in for 1–2 weeks post-procedure.
PCNL — Percutaneous Nephrolithotomy
For large stones (>20mm) in the kidney. A track is made through the back directly into the kidney and the stone is fragmented and removed under direct vision. Requires general anaesthetic and usually a 1–3 day hospital stay.
Preventing Kidney Stones
Around 50% of people who have one kidney stone will have another within 5–10 years. Prevention is essential:
Fluid Intake (Most Important)
Drink at least 2–2.5 litres of fluid per day — enough to keep urine pale yellow. Water is best. Lemon juice in water may help (citrate inhibits stone formation). Increase fluid intake in hot weather, during exercise, and if you have a fever. Avoid soft drinks (particularly cola — contains phosphoric acid).
Dietary Changes by Stone Type
- Calcium oxalate stones: Maintain normal calcium intake (do NOT restrict calcium — low dietary calcium paradoxically increases stone risk); reduce high-oxalate foods (spinach, rhubarb, nuts, chocolate, tea); reduce salt (sodium increases calcium excretion); reduce animal protein
- Uric acid stones: Reduce high-purine foods (offal, game, oily fish, shellfish); reduce alcohol; alkalinise urine with potassium citrate (prescription)
- Struvite stones: Treat underlying recurrent UTIs; long-term antibiotics may be needed
Medications for Prevention
- Potassium citrate — alkalinises urine and provides citrate; effective for calcium oxalate and uric acid stones
- Thiazide diuretics (e.g., bendroflumethiazide) — reduce calcium excretion in urine; for recurrent calcium stones with hypercalciuria
- Allopurinol — reduces uric acid production; for uric acid stones or calcium stones with hyperuricosuria
This article is for informational purposes only. If you think you have a kidney stone, seek medical advice. If you have a fever with flank pain, go to A&E immediately — this may indicate a blocked, infected kidney requiring emergency treatment.
Related Health Guides on YourHealthXpert
Explore these related NHS-aligned health guides:
- Chronic Kidney Disease Guide — Recurrent kidney stones can damage kidney function over time; learn about NHS CKD monitoring and care.
- High Blood Pressure Guide — Hypertension is both a cause and consequence of kidney damage from stones; understand the NHS treatment approach.
- Gout Guide — Uric acid kidney stones and gout share the same root cause; learn how managing one helps the other.
- Type 2 Diabetes Guide — Diabetes increases kidney stone risk through changes in urine chemistry; understand the NHS management pathway.
- IBS Guide — Gut absorption issues in IBS can increase oxalate kidney stones; learn about the NHS dietary management approach.
- Osteoporosis Guide — Calcium restriction to prevent stones can affect bone density; understand the NHS balance between stone prevention and bone health.