Introduction

Urolithiasis is a disease characterized by the formation of stones within the urinary tract, mostly in the kidney and ureter, although it may also affect the bladder and urethra. Stone disease can be classified based on the stone location and composition, or stratified based on etiology into infectious, noninfectious, genetic, or drug-induced (drug stones) categories.1 Urolithiasis is a substantial global concern. Its rising incidence is closely linked to modern dietary patterns, sedentary lifestyle, and the growing burden of metabolic disorders, such as obesity and diabetes.2 In a recent study, the prevalence of urolithiasis in Poland was estimated at 12.85%.3 Nutritional and lifestyle factors significantly influence the risk of stone formation by altering urinary composition and promoting salt supersaturation.4 Renal calculi often remain asymptomatic, and are detected during diagnostic workup of hematuria or other unrelated reasons.5 The condition ranges in severity from acute symptoms, such as renal colic-like pain, to chronic complications, including hypertension, hydronephrosis, and kidney disease.4 Beyond its clinical impact, urolithiasis contributes to psychological strain, reduced productivity, and substantial health care costs.6 In the United Kingdom, treatment expenses rival those incurred by patients with bladder and prostate cancers, while in the United States (US), annual costs are estimated to reach 30 billion USD by 2030.7,8 Given the significant impact of urolithiasis on public health, its high prevalence, and the substantial advances in diagnostic and therapeutic methods, the aim of this review is to present the current state of knowledge regarding the epidemiology, diagnostic approaches, and treatment strategies for urinary stone disease.

Epidemiology

Urolithiasis is a common disease, with estimated prevalence ranging between 1% and 20% in different populations.9 The variability in prevalence is attributed to a complex interplay of multiple influencing factors, predominantly geographical, cultural, climatic, dietary, genetic, and lifestyle-related.9

Based on a 2021 Global Burden of Disease Study,10 estimated incidence of urolithiasis was 106 million new diagnoses globally, with men accounting for approximately 67% of these cases. Growing prevalence of urolithaisis has been also observed worldwide, especially in developed countries. In the US, the prevalence of urolithiasis increased and is now estimated at 8.8%.11 In Europe, it is approximated that between 25 and 49 million individuals were living with symptomatic kidney stones in 2011.12 An increasing trend was noted in Iceland, with prevalence reaching 6.2%.2 In Germany, the rise in incidence was not so evident, as it progressed from 4% to 4.7% from 1979 to 2001, although in the older population (>65 years), the prevalence peaked at 9.5%. Similar trends were observed in Spain, with an increase from 4.2% in 1986 to 5.1% in 2007.12,13 In Poland, the prevalence of urolithiasis was estimated at 12.85%, with a significantly higher rate of approximately 16.87% found in the older population (>60 years).3 Notably, higher rates of urolithiasis have been observed outside of Europe, particularly in Saudi Arabia, where the prevalence is estimated at 20.1%.14,15 This may be attributed to higher ambient temperatures, a well-established risk factor for the disease.

The risk of recurrence depends on the individual risk of stone forming. It is estimated that about 50% of recurrent stone formers experience a single episode of recurrence over their lifetime. However, urolithiasis is characterized by high recurrence rates; nearly 60% of individuals experience renal colic-like pain symptoms 10 years after initial treatment.16 The recurrence rate is higher in individuals with specific stone compositions, in whom it can reach up to 82.4%.11

Pathophysiology and risk factors

Mechanism of stone formation

Urolithiasis develops when urinary solutes crystallize and gradually accumulate into stones. This process is heavily influenced by a range of factors, both inherited (eg, cystinuria) and environmental. Central to the formation of calculi is urinary supersaturation—a state where solute concentrations surpass their solubility threshold, leading to crystal nucleation, growth, and aggregation.17,18 The primary contributors to urinary stone disease are insufficient fluid intake and reduced urine output,19 whereas the 4 key biochemical abnormalities associated with stone formation include elevated urinary calcium (hypercalciuria), oxalate (hyperoxaluria), and uric acid (hyperuricosuria) levels, along with decreased citrate excretion (hypocitraturia).20 These aggregates can obstruct urinary flow, especially at anatomically narrow regions, such as the ureteropelvic junction (the site where the ureter crosses the iliac vessels) and the ureterovesical junction. Such blockages often result in hydronephrosis and provoke renal colic through ureteral stretching and inflammation driven by prostaglandin activity.

Types of stones and underlying mechanisms

Based on mineralogical composition, kidney stones can be divided into 5 main types: calcium oxalate (65.9%), carbapatite (15.6%), urate (12.4%), struvite (2.7%), and brushite (1.7%) stones.21,22 Several mechanisms have been described as responsible for the formation of the most prevalent stone type, that is, calcium oxalate stones. These include abnormal renal handling of calcium and oxalate, excessive urinary saturation, and structural predispositions, such as Randall plaques, that is, subepithelial calcifications found near the loops of Henle. There is also evidence suggesting that interstitial apatite deposits may act as an initiating point for stone development, though their role is still under investigation.23,24 Overall, 2 main theories have been proposed regarding stone formation: 1) the free particle theory, involving crystal aggregation in fluid, and 2) the fixed particle theory, involving growth on anchored plaques.25

Distinct etiologic mechanisms for individual stone types

Each type of kidney stone is associated with a distinct underlying etiologic mechanism, reflecting differences in metabolic, environmental, or genetic contributing factors. Calcium stones are often linked to conditions such as hyperparathyroidism, renal calcium wasting, idiopathic or absorptive hypercalciuria, low magnesium levels, and hypocitraturia.26 Uric acid stones form primarily in persistently acidic urine (pH <⁠5.5), often in association with a high intake of purine-rich foods, malignancies, or gout.27 Struvite stones are typically associated with infections by urease-producing gram-negative bacteria, such as Proteus, Klebsiella, and Pseudomonas. In contrast, Escherichia coli does not contribute to stone formation due to its lack of urease activity.28 Cystine stones are a result of a rare hereditary disorder affecting renal reabsorption of cystine and other dibasic amino acids.29

Medication and genetic influence

Various medications have also been linked to stone formation, particularly atazanavir, triamterene, sulfonamides, indinavir, and ephedrine.30-33 Additionally, genetic factors can predispose individuals to urolithiasis, especially through inherited defects in renal tubular function.34 A family history of nephrolithiasis significantly increases the risk of the disease by about 2.5 times,35 while individuals with a prior episode of stone disease face a 15% risk of recurrence within 1 year and up to 50% over a decade.36

Comorbid conditions and systemic associations

A range of chronic medical conditions have been identified as increasing the risk of stone formation. These include obesity, diabetes, hypertension, metabolic syndrome, and gout, all of which influence urinary chemistry and pH.37 Gastrointestinal diseases, particularly those associated with chronic diarrhea or malabsorption (eg, inflammatory bowel disease or status post–bariatric surgery), can increase urinary oxalate levels, further predisposing patients to calcium oxalate stones.38 Infections with urease-positive organisms increase urinary pH, creating favorable conditions for struvite stone formation.39

Dietary and lifestyle factors

Diet plays a central role in modulating the risk of kidney stone formation. Several dietary factors are strongly linked to increased incidence of the disease. Excessive sodium intake enhances urinary calcium excretion40; high consumption of animal protein elevates uric acid levels, reduces urinary citrate, and lowers urine pH41; and diets rich in oxalate-containing foods (eg, spinach, nuts) contribute to hyperoxaluria.42 Paradoxically, both very low and very high calcium intake can increase oxalate absorption, thereby raising the risk of stone formation.43 Additionally, regular consumption of sugar-sweetened beverages is associated with a 22%–33% higher incidence of nephrolithiasis.44 Conversely, certain dietary habits are protective against stone formation. Ensuring adequate fluid intake to produce at least 2 liters of urine daily is one of the most effective preventive measures.45 A moderate intake of dietary calcium, especially from dairy sources, helps reduce oxalate absorption.43 Diets rich in fruits, vegetables, and dietary fiber promote more alkaline urine and lower the stone risk.46 Additionally, consumption of caffeinated coffee has been associated with a reduced risk of stone formation.47 Although most fruit juices have minimal impact on the disease risk, lemon juice may be beneficial due to its high citrate content, while cranberry juice lacks consistent evidence of efficacy.48

Diagnostic methods

The diagnostic workup of suspected nephrolithiasis requires a structured and individualized approach that integrates clinical evaluation, targeted laboratory studies, and appropriate imaging modalities. The choice of diagnostic tools is informed by patient-specific factors, such as age, pregnancy status, body mass index (BMI), and the urgency of clinical presentation. The overarching goal is to achieve diagnostic accuracy while minimizing exposure to ionizing radiation and optimizing resource use.

A thorough initial evaluation plays a critical role in both diagnosing urolithiasis and identifying alternative or concurrent pathologies. Standard laboratory investigations commonly include: 1) urinalysis with microscopy: a primary diagnostic tool that often reveals hematuria, a hallmark of urinary calculi. The presence of leukocyte esterase, nitrites, or pyuria may indicate concomitant urinary tract infection49; 2) blood or urine human chorionic gonadotropin testing: these tests assist in identifying systemic inflammation, infection, renal function abnormalities, and electrolyte imbalances. In women of reproductive age, pregnancy must be excluded prior to imaging, as it directly influences the selection of safe diagnostic modalities; 3) serum levels of lactic acid, lipase, and amylase: these markers are useful in the differential diagnosis when nonurologic causes of abdominal pain, such as pancreatitis or bowel ischemia, are suspected; 4) blood cultures: recommended in patients exhibiting systemic inflammatory response syndrome criteria, particularly in the context of potentially obstructed, infected stones, where urosepsis is a concern.

Imaging is indispensable in confirming the presence, size, and anatomical location of calculi, as well as in assessing for secondary signs, such as obstruction or infection. Selection of the imaging modality should balance diagnostic accuracy against patient safety.

Ultrasonography

Renal ultrasonography is frequently employed as the first-line imaging modality in populations where radiation exposure is contraindicated or undesirable, such as pregnant patients and children. It is widely available, cost-effective, and does not involve exposure to ionizing radiation.50 On ultrasound, stones are typically visualized as echogenic foci with posterior acoustic shadowing, whereas secondary signs, such as hydronephrosis, may support the diagnosis.49 Despite these advantages, ultrasonography has limitations. Sensitivity and specificity of this modality are 45% and 94%, respectively, for ureteral stones, and 45% and 88%, respectively, for renal stones.51,52

Abdominal radiography

The kidney-ureter-bladder (KUB) plain radiograph is a rapid and inexpensive imaging option, often utilized in emergency settings. However, sensitivity and specificity of this modality are limited and estimated at 44%–74%.53 Therefore, according to the European Association of Urology (EAU) guidelines on urolithiasis, it should not be performed if noncontrast computed tomography (NCCT) is planned.54 KUB radiography is the most effective in identifying radiopaque stones composed of calcium oxalate or phosphate but fails to visualize radiolucent stones, such as those composed of uric acid or cystine.55 Its primary role is in longitudinal surveillance of known stone burden, particularly in patients managed conservatively or followed up after intervention.

Noncontrast computed tomography

NCCT scanning of the abdomen and pelvis remains the gold standard for diagnosing nephrolithiasis in nonpregnant adults.56 It provides high diagnostic accuracy, with sensitivity ranging from 95% to 100% and specificity between 92% and 100%.57,58 Not only can NCCT confirm the presence of calculi regardless of their composition (with the exception of indinavir stones59), but it also delineates stone size, location, and associated complications, such as hydronephrosis or perinephric stranding. Attenuation values (expressed in Hounsfield units) offer additional information that may guide therapeutic decision-making, including the likelihood of success with extracorporeal shock wave lithotripsy (ESWL).

Nevertheless, the use of NCCT must be judicious, particularly in recurrent stone formers, due to cumulative radiation exposure. Low-dose NCCT protocols have emerged as a viable alternative.60 For patients with BMI below 30 kg/m2, low-dose NCCT has demonstrated sensitivity of 86% for identifying ureteral stones smaller than 3 mm, and 100% sensitivity for stones larger than 3 mm.61 However, diagnostic reliability decreases in patients with BMI greater than 30 kg/m2 due to image degradation.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is not routinely used in the evaluation of urolithiasis, but may be considered in specific clinical contexts where radiation exposure is contraindicated (eg, pregnancy). Urinary stones on MRI appear as filling defects.62 Three-Tesla (T) MRI has not been assessed for safety in pregnancy; the use of 1.5T MRI is currently advised.63 Gadolinium contrast agents are generally avoided during pregnancy due to potential toxicity to the embryo. The high cost, limited availability, and relatively long acquisition times restrict the utility of MRI in acute settings, although it may be valuable as a secondary imaging modality in pregnant or pediatric patients when ultrasonography is inconclusive.64,65

Treatment methods

Urolithiasis management is guided by symptom severity, stone size and location, and patient-specific factors. Acute presentations often involve flank pain, nausea, and vomiting—frequently due to ureteral obstruction.66 Immediate management focuses on analgesia, with nonsteroidal anti-inflammatory drugs (including metamizole and paracetamol) being the first-line treatment.67 Opioids seem to be less effective in pain management in renal colic.68 Nausea is addressed with antiemetics, such as metoclopramide. Hydration may correct volume depletion but does not accelerate stone passage.69

Medical expulsive therapy

Medical expulsive therapy facilitates spontaneous stone passage, particularly for ureteral stones 5–10 mm in diameter. Commonly used agents include α-blockers (eg, tamsulosin, silodosin), calcium channel blockers (eg, nifedipine), and phosphodiesterase type 5 inhibitors.70 Though α-blockers are used off-label, evidence supports their efficacy,71 and they are recommended for medical expulsive therapy by the EAU guidelines on urolithiasis, especially for distal stones greater than 5 mm.54

Stones up to 5 mm in diameter have an approximately 90% chance of spontaneous passage within 40 days.72 In a study by Yallappa et al,73 spontaneous passage occurred in around 49% of upper ureteral stones, 58% of midureteral stones, and 68% of those located distally. In terms of size, nearly 75% of calculi measuring less than 5 mm passed without intervention, as compared with 62% of those exceeding 5 mm. The average time to stone passage was around 17 days, with a range spanning from 6 to 29 days.

Indications for emergency intervention

Prompt urologic evaluation and decompression are warranted in the presence of: 1) obstructive uropathy with fever or sepsis, 2) intractable pain or persistent vomiting, 3) a solitary or transplanted kidney with obstruction, 4) bilateral upper urinary tract obstruction or rising creatinine levels, and 5) obstructive pyelonephritis or urosepsis.

These cases require urgent drainage via a ureteral stent or nephrostomy tube. As recognized by the EAU guidelines, there is no evidence suggesting superiority of one method over another. In addition, whereas complications of nephrostomy tube placing have been widely described, there is no high-quality evidence on complications following JJ stent placement.74 Nephrostomy is often preferred in septic individuals, whereas JJ stent placement is preferred in patients on anticuagulation or those with obesity. Definitive stone management is deferred until clinical stabilization.

Surgical management

Extracorporeal shock wave lithotripsy

ESWL is a noninvasive procedure using externally applied shockwaves to fragment stones, typically guided by ultrasonography or fluoroscopy. It is best suited for renal or proximal ureteral stones smaller than 2 cm, except for stones located in lower poles of the kidney,75 with success rates of 60% to 80%.76 Stones larger than 2 cm are best managed with percutaneous nephrolithotomy (PNL), as ESWL typically necessitates multiple sessions and carries a higher risk of ureteral obstruction, such as colic or steinstrasse, often requiring additional interventions.77

Contraindications to ESWL include active infection, pregnancy,78 coagulopathy,79 skeletal deformities, distal obstruction, significant obesity, and vascular anomalies near the stone (aneurysm).80 Postprocedural stenting may be required to prevent steinstrasse (ureteral obstruction by stone fragments). ESWL is associated with a lower overall complication rate than PNL and ureteroscopy (URS).81

Ureteroscopy and retrograde intrarenal surgery

URS involves endoscopic access through the urethra (retrograde access) to treat ureteral and renal stones. Percutaneous, antegrade placement of a flexible URS is also feasible and used in selected cases, such as large, impacted stones in the proximal ureter.82 It provides high stone-free rates and is preferred for distal stones or in patients on anticoagulation.83 For renal stones larger than 2 cm, the overall stone-free rate reached 91%, requiring an average of 1.45 procedures per patient. Additionally, 4.5% of complications were classified as more severe than Clavien–Dindo grade 3.84 URS is performed under fluoroscopy guidance, and a flexible guiding wire should be placed in the collecting system of the kidney. If placement of the instrument in the ureter is not possible, JJ stent insertion followed by URS is an option.85 Extended surgical duration in URS is associated with higher complication rates, highlighting the need to limit operative time to under 90 minutes.86 Holmium lasers are the standard technology for lithotripsy,87 though thulium fiber lasers are gaining in popularity.88 Ureteral access sheaths aid in complex or prolonged procedures.89

Routine stenting before or after uncomplicated URS is generally not necessary and may increase postoperative morbidity and costs.90 However, prestenting can improve stone-free rates and reduce intraoperative complications.91 Stents should still be used in high-risk patients or in uncertain cases to prevent complications and avoid emergencies. Although the optimal stenting duration is unclear, most urologists favor leaving the stent in place for 1 to 2 weeks; treatment with α-blockers can help improve stent tolerability.92 URS is appropriate for stones larger than 2 cm when ESWL or PNL are contraindicated. Complications after URS occur in 9%–25% of cases.72 They are mostly minor, with urosepsis seen in up to 5% of patients, and serious events, such as ureteral avulsion, affecting less than 1% of indiviuals.93 Key risk factors include prior perforation, positive urine cultures, and prolonged surgery.86 Preventive measures include prophylactic antibiotics, minimizing stent and procedure time, treating urinary tract infections, and careful planning in complex cases.94 There are no established contraindications to URS.

Percutaneous nephrolithotomy

PNL is the gold standard for managing large (>2 cm) renal calculi, including staghorn stones. It entails percutaneous access to the collecting system, often under CT or ultrasound guidance. Both supine and prone positions are acceptable. Standard access sheath size is 24–30 French (Fr). Mini-PNL (12–22 Fr) offers similar efficacy to the standard procedure, with reduced morbidity.95 Furthermore, even smaller sheaths (<⁠18 Fr), originally designed for pediatric use, are increasingly used in the adult population.95,96 Flexible nephroscopy helps retrieve residual stone fragments. Tubeless (without placing a nephrostomy tube) and totally tubeless techniques (without a nephrostomy tube or ureteral stent) may reduce postoperative pain and shorten recovery.97 Intraoperative urine cultures are valuable for predicting the infection risk and facilitating treatment choice in the case of postsurgery sepsis.98 Contraindications include pregnancy, uncorrected bleeding disorders, untreated urinary tract infections, and malignancy involving the access tract or a potentially malignant renal tumor. A systematic review encompassing nearly 12 000 patients reported the following complication rates associated with PNL: fever in 10.8% of cases, blood transfusion in 7%, and thoracic complications in 1.5%. More severe complications, such as sepsis, organ injury, embolization, urinoma, and death were reported in less than 1% of patients.99

Open or laparoscopic surgery

Rarely indicated, these approaches are reserved for patients in whom less invasive methods were ineffective, or simultaneously during other urinary tract surgeries.54

Conclusions

Urolithiasis is a prevalent and increasingly burdensome condition influenced by lifestyle, metabolic, and environmental factors. Accurate diagnosis relies on a combination of clinical assessment, laboratory tests, and appropriate imaging, with low-dose NCCT being the gold standard in most cases. Treatment strategies range from conservative management and medical expulsive therapy to minimally invasive procedures, such as ESWL, URS, and PNL, and the choise of an appropriate method must me individualized. Advances in surgical techniques and supportive care have significantly improved patient outcomes, but recurrence prevention through lifestyle and dietary modification remains a cornerstone of long-term management.