My Clinical Approach
Nephrolithiasis is one of the most frequent conditions bringing patients to the urology clinic — often as an emergency. Renal colic is among the most intense pains in medicine, and every patient who has experienced it remembers exactly when and where it began.
In daily practice, what I have observed is that removing the stone is only half the work. The other half — often the more important one — is finding out why the stone formed, so it does not return. Without proper metabolic evaluation and prevention, the recurrence rate reaches 50% within the first 5 years.
The approach I follow is based on the EAU Urolithiasis 2024 and AUA guidelines:
- Always low-dose NCCT for accurate diagnosis and stone mapping.
- Emergency decompression when infection or obstruction of a solitary kidney coexists — antibiotics alone are not enough.
- Choice of technique (ESWL / URS-Laser / PCNL) tailored to size, location, composition and anatomy.
- Analysis of every stone removed and metabolic workup in high-risk patients.
Modern urological care for stones is not just lithotripsy — it is an integrated plan of triage, acute management and long-term prevention.
What is Nephrolithiasis
Nephrolithiasis is the aggregation of crystals (mainly calcium, oxalate, uric acid or phosphate) in the urine, forming solid stones inside the kidney or ureter. It is the most common benign urological disease and is clearly distinct from other kidney pathologies.
By location and type, the main categories are:
Renal stones (pyelocaliceal system)
Form within the calyces or renal pelvis. Often asymptomatic while they remain there — they become symptomatic when they migrate into the ureter.
Ureteric stones
Cause the typical renal colic. Classified as proximal (pyeloureteric junction), mid-ureteric and distal (vesicoureteric junction). Location dictates the choice of treatment.
Staghorn stone
A large stone filling part or all of the pyelocaliceal system. Usually composed of struvite, on a background of chronic infection. Almost always requires percutaneous nephrolithotomy (PCNL) as first choice.
What nephrolithiasis is not
Nephrolithiasis must not be confused with nephrocalcinosis (diffuse calcium deposition in the renal parenchyma), with simple kidney cysts, or with cholelithiasis (gallstones), which is an entirely different condition despite the linguistic similarity.
How Common It Is
Nephrolithiasis affects 10–15% of the population over a lifetime, with incidence rising internationally over recent decades. Mediterranean countries, Greece included, have one of the highest rates in Europe due to dry climate and dietary habits.
The disease is more common in men (~2:1 ratio), with peak incidence between 30 and 60 years of age. Major risk factors:
Low fluid intake
The most important modifiable factor. Urine output < 1.5 L/24h quadruples the risk.
High sodium and animal protein diet
Increases urinary excretion of calcium and uric acid.
Obesity and metabolic syndrome
Associated with hypercalciuria, hyperuricaemia and low urine pH.
Family history
Risk is 2–3 times higher in first-degree relatives.
Anatomical variants
Pyeloureteric junction obstruction, medullary sponge kidney, horseshoe kidney.
Systemic diseases
Primary hyperparathyroidism, gout, Crohn disease, chronic urinary infections.
Important: After a first stone, the risk of recurrence without prevention reaches 50% at 5 years and 75% at 20 years. Nephrolithiasis must be treated as a chronic disease, not as an isolated episode.
Symptoms & Renal Colic
Many stones, particularly small renal ones, remain asymptomatic and are discovered incidentally on ultrasound or CT. Symptoms appear when the stone migrates into the ureter and causes obstruction.
Renal colic
Intense, cramping pain in the loin or flank radiating to the groin, testicle or labia majora. The patient writhes restlessly seeking relief — a characteristic distinction from peritonitis where the patient remains motionless.
Haematuria
Present in ~85% of cases, microscopic or visible. Absence of haematuria does not exclude the diagnosis.
Associated symptoms
Nausea, vomiting (from reflex vagal stimulation), frequency and urgency (when the stone is in the distal ureter near the bladder), dysuria.
When immediate specialist evaluation is needed
- Fever > 38°C with chills and flank pain (stone + infection = emergency).
- Persistent vomiting that prevents hydration and oral therapy.
- Pain that does not subside with standard analgesia within 6 hours.
- Oliguria or anuria (suspicion of bilateral or solitary-kidney obstruction).
- Stone in pregnancy, in a solitary kidney or with established renal failure.
Diagnosis and Imaging
Accurate diagnosis rests on two pillars: stone characterisation by imaging and laboratory workup for complications and underlying causes.
Low-dose non-contrast CT (NCCT)
The gold standard per EAU 2024. It provides:
- Sensitivity > 95% and specificity > 96% for all stone types.
- Accurate measurement of size, location and density in Hounsfield Units (HU).
- Information on degree of hydronephrosis and possible complication (perinephric urine extravasation).
- HU < 800 typically favours ESWL; HU > 1000 often requires laser.
Additional imaging
Renal & bladder ultrasound
First choice in pregnancy, children and young patients. Detects hydronephrosis and renal stones, but often misses mid-ureteric stones.
Plain KUB radiograph
Useful for follow-up of radio-opaque (calcium-based) stones after treatment. Does not show radiolucent uric acid stones.
Contrast CT urography
In suspicion of coexisting anatomical anomaly or in ambiguous findings, for accurate mapping before interventional therapy.
Basic laboratory workup
- Urinalysis + urine culture (exclude infection before any intervention).
- Full blood count, CRP (look for leucocytosis / sepsis).
- Creatinine, eGFR, electrolytes (assess renal function).
- Serum calcium, uric acid, PTH if hyperparathyroidism is suspected.
Important: Urine culture before every endoscopic intervention
Endoscopic stone treatment in subclinical urinary infection can trigger urosepsis through increased intrapelvic pressure and bacteraemia. Per EAU 2024, urine culture and appropriate antibiotic cover are mandatory before any ESWL, URS or PCNL.
Stone Composition & Metabolic Workup
Per EAU, chemical analysis of every stone removed is mandatory. Composition guides both treatment choice and prevention strategy. The main stone types:
Calcium stones (~75–80%)
Calcium oxalate monohydrate or dihydrate, less commonly calcium phosphate. Associated with hypercalciuria, hyperoxaluria or hypocitraturia. Hard, often requiring Holmium laser for fragmentation.
Uric acid stones (~10%)
Form in low urine pH (< 5.5) and hyperuricaemia. Radiolucent (invisible on plain X-ray). Characteristically can be chemically dissolved by urinary alkalinisation (citrate salts, target pH 6.5–7).
Struvite stones (~5–10%)
Magnesium ammonium phosphate. Form in chronic infections by urease-producing bacteria (Proteus, Klebsiella). Often staghorn, growing rapidly. Complete removal via PCNL combined with targeted antibiotics is mandatory.
Cystine stones (~1%)
From hereditary cystinuria. Often early-onset, recurrent, hard to fragment. Prevention requires high hydration (>3 L/24h), alkalinisation and, in severe cases, thiola or captopril.
24-hour urine metabolic workup
In high-risk patients (recurrent formers, solitary kidney, children, family history, non-calcium stones), two 24-hour urine collections are recommended for volume, calcium, oxalate, citrate, uric acid, sodium, magnesium and pH. The findings guide individualised pharmacological prevention (thiazides, potassium citrate, allopurinol).
Treatment and Follow-up
Management is individualised based on size, location, composition and the patient's clinical status:
Conservative management & Medical Expulsive Therapy (MET)
Stones ≤ 10 mm in the distal ureter without infection or obstruction can be managed with analgesia (NSAIDs or paracetamol), hydration and tamsulosin 0.4 mg/day. Tamsulosin relaxes the distal ureter and increases spontaneous passage of 5–10 mm stones by ~20%. Reassess in 2–4 weeks with NCCT.
Extracorporeal Shock Wave Lithotripsy (ESWL)
Non-invasive method for renal stones ≤ 20 mm with density < 1000 HU. Shock waves break the stone into small fragments that pass with the urine. Usually requires 1–3 sessions. Contraindicated in pregnancy, coagulopathy, untreated urinary infection and obstruction distal to the stone.
Ureteroscopy with Holmium Laser (URS / RIRS)
Endoscopic approach for ureteric stones at any level and renal stones 10–20 mm with flexible ureteroscopy (RIRS). The Holmium laser fragments the stone into dust or pieces that are extracted with a basket. General anaesthesia is required.
Percutaneous Nephrolithotomy (PCNL)
First choice for renal stones > 20 mm, staghorn stones and multiple lower-pole stones. A small tract is created through the lumbar wall to the kidney under ultrasound or fluoroscopic guidance.
Emergency decompression: JJ Stent or Percutaneous Nephrostomy
In sepsis with an obstructed kidney, definitive stone treatment is deferred. The first priority is decompression within hours by cystoscopic JJ stent or ultrasound-guided percutaneous nephrostomy. Antibiotics are given concurrently. Stone treatment is performed 2–4 weeks later.
When Intervention Is Needed
Indications for interventional therapy per EAU 2024 are:
- Stone > 10 mm (unlikely spontaneous passage).
- Stone that has not progressed after 4–6 weeks of observation.
- Persistent pain not controlled by analgesia.
- Renal failure due to obstruction.
- Coexisting infection (sepsis — emergency).
- Stone in a solitary kidney or in bilateral disease.
- Stone in pregnancy (in selected cases, with URS).
- Occupational reasons (e.g. pilots, professional drivers).
Ureteroscopy with Holmium laser currently offers the highest stone-free rate for ureteric and mid-size renal stones. For stones > 20 mm, PCNL remains the gold standard. ESWL retains its role as a non-invasive option in selected cases.
Recurrence Prevention & Prognosis
Nephrolithiasis is a chronic disease: without prevention, recurrence reaches 50% at 5 years. With proper interventions, the risk can drop to 10–15%.
- Target urine output ≥ 2 L/24h (fluid intake > 2.5 L) — the single most important factor.
- Moderate animal protein intake (≤ 1 g/kg/24h) and sodium (≤ 5 g salt/24h).
- Adequate dietary calcium (1000–1200 mg/24h) — calcium supplements increase risk.
- Citrate (lemon, orange) protects via urinary alkalinisation.
- In hypercalciuria: thiazides (HCT 25 mg).
- In uric acid stones or hyperuricosuria: alkalinisation + allopurinol.
- In struvite: complete removal + targeted antibiotics + culture follow-up.
Post-treatment follow-up is at 4–6 weeks with NCCT or ultrasound + KUB to confirm stone-free status. In high-risk patients, annual ultrasound and 24-hour urine every 1–2 years.
In summary: Modern stone management is minimally invasive and rests on individualised technique choice and — equally important — on evidence-based long-term recurrence prevention.
Frequently Asked Questions (FAQ)
How do I distinguish renal colic from other abdominal pain?
Renal colic is intense, cramping pain in the flank or loin radiating to the groin or genitalia. The patient cannot find a position of relief, in contrast to peritonitis where stillness helps. It is often accompanied by nausea, vomiting and microscopic or visible haematuria. Definitive distinction is made by non-contrast CT (NCCT).
Which is the most reliable diagnostic test?
According to EAU 2024 guidelines on urolithiasis, low-dose non-contrast CT (NCCT) is the gold standard, with sensitivity > 95% and specificity > 96%. It detects nearly all stones, measures size, density in Hounsfield Units and the level of obstruction. Ultrasound remains useful in pregnancy and young patients, but misses small ureteric stones.
Will the stone pass on its own?
Stones ≤ 5 mm pass spontaneously in approximately 70–80% of cases, stones 5–10 mm in about 50%. Stones > 10 mm rarely pass without intervention. Medical expulsive therapy (MET) with an alpha-blocker such as tamsulosin 0.4 mg daily increases the probability of spontaneous passage of distal ureteric stones 5–10 mm by approximately 20%.
When is emergency treatment needed?
The combination of a stone with infection (fever, chills, leucocytosis) or bilateral obstruction or obstruction of a solitary kidney constitutes an emergency. Immediate decompression is required within hours by JJ stent or percutaneous nephrostomy, regardless of stone size. Definitive stone treatment is performed in a second stage after sepsis resolves.
Which treatment is appropriate for each stone?
Choice depends on size, location and composition: extracorporeal shock wave lithotripsy (ESWL) for renal stones ≤ 20 mm, flexible ureteroscopy with Holmium laser (RIRS) for stones 10–20 mm of the kidney and most ureteric stones, and percutaneous nephrolithotomy (PCNL) for stones > 20 mm or for staghorn stones. Open surgery is now rare.
What is a staghorn stone?
It is a large stone that fills part or the whole of the pyelocaliceal system, taking the shape of a stag’s horn. It is usually composed of struvite (magnesium ammonium phosphate) and forms in chronic infections by urease-producing bacteria (Proteus, Klebsiella). It can gradually destroy renal function and almost always requires percutaneous nephrolithotomy (PCNL) as first choice per EAU/AUA.
How can I prevent recurrence?
Prevention rests on three pillars: adequate hydration (>2.5 L/day, targeting urine output ≥ 2 L), dietary changes (moderate restriction of animal protein and sodium, adequate dietary calcium intake — not supplements) and, in selected cases, medications such as citrate salts or thiazides depending on the findings of 24-hour urine metabolic workup.
Is metabolic workup needed after a single stone?
Yes in high-risk patients: children, recurrent stone formers, renal failure, solitary kidney, family history, non-calcium stones (uric acid, struvite, cystine). It includes stone composition analysis, 24-hour urine (calcium, oxalate, citrate, uric acid, sodium, volume), blood biochemistry and urine pH. It guides individualised prevention.
Related Topics
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If you are dealing with renal colic, have been diagnosed with a stone or have a history of recurrent stones, proper urological evaluation is essential. Treatment choice and prevention strategy are always individualised.
References – Sources
- EAU Guidelines on Urolithiasis 2024 — uroweb.org
- Assimos D, et al. Surgical Management of Stones: AUA/Endourological Society Guideline. J Urol 2016;196:1153.
- Pearle MS, et al. Medical Management of Kidney Stones: AUA Guideline. J Urol 2014;192:316.
- Hollingsworth JM, et al. Alpha blockers for treatment of ureteric stones: systematic review and meta-analysis. BMJ 2016;355:i6112.
- NIDDK — Kidney Stones — niddk.nih.gov
Medical Editorial
Dr. Marinos Vasilas, Urologist – Andrologist
Dr. Marinos Vasilas runs a private urology practice in Rhodes, with particular expertise in endoscopic and percutaneous management of nephrolithiasis (Holmium laser, RIRS, PCNL) as well as in the emergency management of obstructed and septic kidney. He emphasises individualised long-term recurrence prevention with metabolic workup per EAU 2024.
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