Urolithiasis

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EAU GUIDELINES ON UROLITHIASIS

(Limited text update March 2016)

C. Türk (Chair), T. Knoll (Vice-chair), A. Petrik, K. Sarica, C. Seitz, A. Skolarikos, M. Straub

Guidelines Associates: S. Dabestani, T. Drake, N. Grivas,

Y. Ruhayel, A.K. Tepeler

Eur Urol 2014 Nov 20. pii: S0302-2838(14)01102-6.

Aetiology and classification

Urinary stones can be classified according to the following aspects: aetiology of stone formation, stone composition (mineralogy), stone size, stone location and X-ray characteristics of the stone. The recurrence risk is basically determined by the disease or disorder causing the stone formation.

Risk groups for stone formation

The risk status of stone formers is of particular interest because it defines the probability of recurrence or regrowth, and is imperative for pharmacological treatment (Table 1).

Table 1: High-risk stone formers

General factors

Early onset of urolithiasis (especially children and teenagers)

Familial stone formation

Brushite-containing stones (CaHPO4.2H2O)

Uric acid and urate-containing stones

Infection stones

Solitary kidney (the kidney itself does not particularly increase risk of stone formation, but prevention of stone recurrence is of more importance)

Diseases associated with stone formation

Hyperparathyroidism

Metabolic syndrome

Nephrocalcinosis

Gastrointestinal diseases (i.e., jejuno-ileal bypass, intestinal resection, Crohn’s disease, malabsorptive conditions, enteric hyperoxaluria after urinary diversion) and bariatric surgery

Sarcoidosis

Spinal cord injury, neurogenic bladder

Genetically determined stone formation

Cystinuria (type A, B and AB)

Primary hyperoxaluria (PH)

Renal tubular acidosis (RTA) type I

2,8-dihydroxyadeninuria

Xanthinuria

Lesch-Nyhan syndrome

Cystic fibrosis

Drugs associated with stone formation

Anatomical abnormalities associated with stone formation

Medullary sponge kidney (tubular ectasia)

Ureteropelvic junction (UPJ) obstruction

Calyceal diverticulum, calyceal cyst

Ureteral stricture

Vesico-uretero-renal reflux

Horseshoe kidney

Ureterocele

Diagnostic evaluation

Diagnostic imaging

Standard evaluation of a patient includes taking a detailed medical history and physical examination. The clinical diagnosis should be supported by appropriate imaging.

Recommendation

LE

GR

With fever or solitary kidney, and when diagnosis is doubtful, immediate imaging is indicated.

4

A*

*Upgraded following panel consensus.

Ultrasonography should be used as the primary diagnostic imaging tool although pain relief, or any other emergency measures should not be delayed by imaging assessments.

KUB should not be performed if non-contrast enhanced computed tomography (NCCT) is considered, but KUB can differentiate between radiolucent and radiopaque stones and serve for comparison during follow-up.

Evaluation of patients with acute flank pain

Recommendation for radiologic examinations of patients with acute flank pain/suspected ureteral stones

LE

GR

Following initial US assessment, use NCCT to confirm stone diagnosis in patients with acute flank pain, as it is superior to IVU.

1a

A

IVU=intravenous urography; NCCT=non-contrast enhanced computed tomography; US=ultrasound.

Recommendations for radiologic examination of patients with renal stones

LE

GR

Perform a contrast study if stone removal is planned and the anatomy of the renal collecting system needs to be assessed.

3

A*

Use enhanced CT in complex cases because it enables 3D reconstruction of the collecting system, as well as measurement of stone density and skin-to-stone distance. IVU may also be used.

4

C

*Upgraded following panel consensus.

CT=computed tomography; IVU=intravenous urography.

Diagnostics - Metabolism-related

Each emergency patient with urolithiasis needs a succinct biochemical work-up of urine and blood besides imaging studies; no difference is made between high- and low-risk patients.

Recommendations: basic laboratory analysis - emergency stone patient

GR

Urine

Dipstick test of spot urine sample

red cells

white cells

nitrite

approximate urine pH

Urine microscopy and/or culture

A*

A

Blood

Serum blood sample

creatinine

uric acid

(ionised) calcium

sodium

potassium

blood cell count

CRP

A*

Perform a coagulation test (PTT and INR) if intervention is likely or planned.

A*

*Upgraded following panel consensus.

CPR=C-reactive protein; INR=international normalised ratio; PTT=partial thromboplastin time.

Examination of sodium, potassium, CRP, and blood coagulation time can be omitted in the non-emergency stone patient. Patients at high risk for stone recurrences should undergo a more specific analytical programme (see Section on Metabolic Evaluation below).

Recommendations related to stone analysis

LE

GR

Perform stone analysis in first-time formers using a validated procedure (XRD or IRS).

2

A

Repeat stone analysis in patients:

presenting with recurrent stones despite drug therapy;

with early recurrence after complete stone clearance;

with late recurrence after a long stone-free period because stone composition may change.

2

B

IRS=infrared spectroscopy; XRD=X-ray diffraction.

Diagnosis for special groups/conditions

Pregnancy

Recommendation

LE

GR

Use ultrasound as the preferred method of imaging in pregnant women.

1a

A*

In pregnant women, use MRI as a second-line imaging modality.

3

C

In pregnant women, use low-dose CT as a last-line option.

3

C

*Upgraded following panel consensus.

CT=computed tomograpy; MRI=magnetic resonance imaging.

Children

Recommendations

GR

In children, use ultrasound as first-line imaging modality when a stone is suspected; it should include the kidney, fluid-filled bladder and the ureter next to the kidney and the (filled) bladder.

B

If US does not provide the required information, perform a KUB radiography (or low-dose NCCT).

B

Collect stone material for analysis to classify the stone type.

A*

In all paediatric patients, complete a metabolic evaluation based on stone analysis as they have a high risk of recurrence.

A

KUB=kidney, ureter, bladder; NCCT=non-contrast enhanced computer tomography; US=ultrasound.

Disease Management

Acute treatment of a patient with renal colic

Pain relief is the first therapeutic step in patients with an acute stone episode.

Recommendations for pain relief during and prevention of recurrent renal colic

LE

GR

First choice: start with an NSAID as the first drug of choice. e.g. metamizol (dipyrone); alternatively, depending on cardio-vascular risk factors diclofenac*, indomethacin or ibuprofen**.

1b

A

Second choice: hydromorphine, pentazocine and tramadol.

4

C

Use α-blockers to reduce recurrent colic in informed patients.

1a

A

* Caution: Diclofenac sodium affects glomerular filtration rate in patients with reduced renal function, but not in patients with normal renal function (LE: 2a).

** Recommended to counteract recurrent pain after renal colic (see extended document).

NSAID=non-steroidal anti-inflammatory drug.

If analgesia cannot be achieved medically, drainage, using stenting or percutaneous nephrostomy, or stone removal, should be performed.

Management of sepsis in the obstructed kidney

The obstructed, infected kidney is a urological emergency.

Recommendations

LE

GR

Urgently decompress the collecting system in case of sepsis with obstructing stones, using percutaneous drainage or ureteral stenting.

1b

A

Delay definitive treatment of the stone until sepsis is resolved.

1b

A

In exceptional cases, with severe sepsis and/or the formation of abscesses, an emergency nephrectomy may become necessary.

Recommendations - Further Measures

GR

Collect (again) urine for antibiogram following decompression.

A*

Start antibiotics immediately

(+ intensive care if necessary).

Re-evaluate antibiotic treatment regimen following antibiogram findings.

* Upgraded following panel consensus.

Stone relief

Observation of ureteral stones

Observation of ureteral stones is feasible in informed patients who develop no complications (infection, refractory pain, deterioration of kidney function).

Recommendations

LE

GR

In patients with newly diagnosed small* ureteral stones, if active stone removal is not indicated, observe patient initially along with periodic evaluation.

1a

A

Offer patients appropriate medication to facilitate stone passage during observation.

*see stratification data (J Urol, 2007. 178: 2418).

Observation of kidney stones

It is still debatable whether kidney stones should be treated, or whether annual follow-up is sufficient for asymptomatic caliceal stones that have remained stable for 6 months.

Recommendations

GR

Assess comorbidity, stone composition if possible and patient preference when making treatment decisions.

C

Medical expulsive therapy (MET)

Medical expulsive therapy (MET) should only be used in informed patients. Treatment should be discontinued if complications develop (infection, refractory pain, deterioration of kidney function). Patients who elect for an attempt at spontaneous passage or MET should have well-controlled pain, no clinical evidence of sepsis, and adequate renal functional reserve.

Recommendations for MET

LE

GR

Offer α-blockers as MET as one of the options.

1a

C

Counsel patients regarding the lack of efficacy in a recent large multicentre trial, attendant risks of MET, including associated drug side effects as well as inform the patients that α-blockers are administered off-label†**.

A*

Follow up patients in short intervals to monitor stone position and assess for hydronephrosis.

4

A*

*Upgraded following panel consensus.

** MET using α-blockers in children and during pregnancy cannot be recommended due to the limited data in this specific population.

† It is not known if tamsulosin harms the human foetus or if it is found in breast milk.

Chemolytic dissolution of stones

Oral chemolysis of stones or their fragments can be useful in uric acid stones. It is based on alkalinisation of urine by application of alkaline citrate or sodium bicarbonate. The pH should be adjusted to 7.0-7.2.

Recommendations - Oral chemolysis

GR

Inform the patient how to monitor and modify the dosage of alkalising medication according to urine pH, which is a direct consequence of such medication.

A

Carefully monitor radiolucent stones during/after therapy.

A*

Inform the patient of the significance of compliance.

A

*Upgraded following panel consensus.

Percutaneous irrigation chemolysis is rarely used any more.

SWL

The success rate for SWL will depend on the efficacy of the lithotripter and on:

Size, location (ureteral, pelvic or caliceal), and composition (hardness) of the stones;

Patient’s habitus;

Performance of SWL.

Contraindications of SWL

Contraindications to the use of SWL are few, but include:

Pregnancy;

Bleeding diatheses; which should be compensated for at least 24 h before, and 48 h after, treatment;

Untreated urinary tract infections (UTIs);

Severe skeletal malformations and severe obesity, which prevent targeting of the stone;

Arterial aneurysm in the vicinity of the stone;

Anatomical obstruction distal of the stone.

Best clinical practice (best performance) in SWL

Stenting prior to SWL

When treating kidney stones, a JJ stent reduces the risk of renal colic and obstruction, but does not reduce formation of steinstrasse or infective complications.

Recommendation

LE

GR

Do no routinely use a stent as part of SWL treatment of ureteral stones.

1b

A

SWL=shock wave lithotripsy.

Pacemaker

Patients with a pacemaker can be treated with SWL. Patients with implanted cardioverter defibrillators must be managed with special care (firing mode temporarily reprogrammed

during SWL treatment). However, this might not be necessary with new-generation lithotripters.

Shock waves, energy setting and repeat treatment sessions

The number of shock waves that can be delivered at each session depends on the type of lithotripter and shockwave power.

Starting SWL on a lower energy setting with step-wise power (and SWL sequence) ramping prevents renal injury.

Clinical experience has shown that repeat sessions are feasible (within 1 day for ureteral stones).

Recommendation - Shock wave rate

LE

GR

Use a shock wave frequency of 1.0-1.5 Hz.

1a

A

Procedural control

Recommendation - Procedural control

LE

GR

Maintain careful fluoroscopic and/or ultrasonographic monitoring during the procedure.

A*

Ensure correct use of the coupling agent as this is crucial for effective shock wave transportation.

2a

B

Use proper analgesia as it improves treatment results by limiting induced movements and excessive respiratory excursions.

4

C

*Upgraded following panel consensus.

Antibiotic prophylaxis

No standard prophylaxis prior to SWL is recommended.

Recommendation

LE

GR

In the case of infected stones or bacteriuria, prescribe antibiotics prior to SWL.

4

C

SWL=shock wave lithotripsy.

Percutaneous nephrolithotomy (PNL)

Contraindications:

Untreated UTI;

Atypical bowel interposition;

Tumour in the presumptive access tract area;

Potential malignant kidney tumour;

Pregnancy.

Best clinical practice

Recommendation - Preoperative imaging

GR

Perform preprocedural imaging, including contrast medium where possible or retrograde study when starting the procedure, to assess stone comprehensiveness and anatomy of the collecting system to ensure safe access to the renal stone.

A*

* Upgraded following panel consensus.

Colon interposition in the access tract of PNL can lead to colon injuries. Pre-operative CT or intra-operative US allows identification of the tissue between the skin and kidney and lowers the incidence of bowel injury.

Recommendations - Intracorporeal lithotripsy

GR

Use ultrasonic, ballistic and Ho:YAG devices for intracorporeal lithotripsy during PNL.

A*

When using flexible instruments, use the Ho:YAG laser since it is currently the most effective device.

* Upgraded following panel consensus.

Ho:YAG=holmium:yttrium-aluminium-garnet (laser);

PNL=percutaneous nephrolithotomy.

Nephrostomy and stents after PNL

Recommendation - Nephrostomy and stents after PNL

LE

GR

In uncomplicated cases, perform a tubeless (without nephrostomy tube) or totally tubeless (without nephrostomy tube and ureteral stent) PNL procedure as it is a safe alternative.

1b

A

PNL=percutaneous nephrolithotomy.

Ureterorenoscopy (URS)

(including retrograde access to renal collecting system, RIRS)

Apart from general problems, for example, with general anaesthesia or untreated UTIs, URS can be performed in all patients without any specific contraindications.

Recommendations

LE

GR

Place a safety wire.

C

Do not perform stone extraction using a basket without endoscopic visualisation of the stone (blind basketing).

4

A*

Use Ho:YAG laser lithotripsy for (flexible) URS.

3

B

In uncomplicated cases there is no need need to insert a stent.

1a

B

*Upgraded following panel consensus.

Ho:YAG=holmium:yttrium-aluminium-garnet (laser); URS=ureterorenoscopy.

An α-blocker can reduce stent-related symptoms.

Open and laparoscopic surgery

Recommendations

LE

GR

Offer laparoscopic or open surgical stone removal in rare cases in which SWL, (flexible) URS and PNL fail, or are unlikely to be successful.

3

C

When expertise is available, perform surgery laparoscopically before proceeding to open surgery, especially when the stone mass is centrally located.

3

C

For ureterolithotomy, perform laparoscopy for large impacted stones when endoscopic lithotripsy or SWL has failed.

2

B

PNL=percutaneous nephrolithotomy; SWL=shockwave lithotripsy; URS=ureterorenoscopy.

Indication for active stone removal and selection of procedure

Ureter:

Stones with a low likelihood of spontaneous passage;

Persistent pain despite adequate pain medication;

Persistent obstruction;

Renal insufficiency (renal failure, bilateral obstruction, single kidney).

Kidney:

Stone growth;

Stones in high-risk patients for stone formation;

Obstruction caused by stones;

Infection;

Symptomatic stones (e.g. pain, haematuria);

Stones > 15 mm;

Stones < 15 mm if observation is not the option of choice;

Patient preference;

Comorbidity;

Social situation of the patient (e.g., profession or travelling);

Choice of treatment.

The suspected stone composition might influence the choice of treatment modality.

STONE REMOVAL

Recommendations

GR

Obtain a urine culture or perform urinary microscopy before any treatment is planned. Exclude or treat UTIs prior to endourologic stone removal.

A*

Offer perioperative antibiotic prophylaxis to all patients undergoing endourological treatment.

A*

Offer active surveillance to patients at high-risk for thrombotic complications in the presence of an asymptomatic caliceal stone.

C

Decide on temporary discontinuation, or bridging of antithrombotic therapy in high-risk patients, in consultation with the internist.

B

Perform retrograde (flexible) ureterorenoscopy if stone removal is essential and antithrombotic therapy cannot be discontinued, since it is associated with less morbidity.

A*

*Upgraded following panel consensus.

UTI=urinary tract infection.

Radiolucent uric acid stones, but not sodium urate or ammonium urate stones, can be dissolved by oral chemolysis.

Figure 1: Treatment algorithm for renal calculi

* The term ‘Endourology’ encompasses all PNL and URS interventions.

PNL=percutaneous nephrolithotomy; RIRS=retrograde renal surgery; SFR=stone-free rate; SWL=shockwave lithotripsy; URS=ureterorenoscopy.

Recommendation for the treatment of renal calculi

GR

Use flexible URS in case PNL or SWL are not an option (even for stones > 2 cm). However, in that case there is a higher risk that a follow-up procedure and placement of a ureteral stent may be needed. In complex stone cases, use open or laparoscopic approaches as possible alternatives.

B

PNL=percutaneous nephrolithotomy; SWL=shockwave lithotripsy; URS=ureterorenoscopy.

Figure 2: Recommended treatment options (if indicated for active stone removal) (GR: A*)

SWL=shock wave lithotripsy; URS=ureterorenoscopy.

Recommendation

GR

Use percutaneous antegrade removal of ureteral stones as an alternative when SWL is not indicated or has failed, and when the upper urinary tract is not amenable to retrograde URS.

A

SWL=shock wave lithotripsy; URS=ureterorenoscopy.

Steinstrasse

Steinstrasse occurs in 4% to 7% of cases after SWL, the major factor in steinstrasse formation is stone size.

Recommendations

LE

GR

Medical expulsion therapy increases the stone expulsion rate of steinstrasse.

1b

A

Treat steinstrasse associated with urinary tract infection/fever preferably with percutaneous nephrostomy.

4

C

Treat steinstrasse when large stone fragments are present with shockwave lithotripsy or ureterorenoscopy.

4

C

Management of patients with residual stones

The indications for active removal of residual stones and selection of the procedure are based on the same criteria as for primary stone treatment. For well-disintegrated stone material in the lower calix, inversion therapy with simultaneous mechanical percussion manoeuvre under enforced diuresis may facilitate stone clearance

Recommendations in case of residual fragments

LE

GR

Identify biochemical risk factors and appropriate stone prevention in patients with residual fragments or stones.

1b

A

Follow-up patients with residual fragments or stones regularly to monitor disease course.

4

C

After SWL and URS, and in the presence of residual fragments, offer MET using an α-blocker to improve fragment clearance.

1a

A

MET=medical expulsive therapy; SWL=shock wave lithotripsy; URS=ureterorenoscopy.

Management of specific patient groups

Management of urinary stones and related problems during pregnancy

Recommendations

GR

Treat all non-complicated cases of urolithiasis in pregnancy conservatively (except those that have clinical indications for intervention).

A

If intervention becomes necessary, place a ureteral stent or a percutaneous nephrostomy tube as readily available primary options.

A*

Use ureteroscopy as a reasonable alternative to avoid long-term stenting/drainage.

A

In case of stent insertion ensure regular follow-up until final stone removal because of the higher encrustation tendency of stents during pregnancy.

B

*Upgraded following panel consensus.

Management of stones in patients with urinary diversion

Patients with urinary diversion are at high risk for stone formation in the renal collecting system and ureter or in the conduit or continent reservoir.

Recommendations

GR

Perform PNL to remove large renal stones in patients with urinary diversion, as well as for ureteral stones that cannot be accessed via a retrograde approach or that are not amenable to SWL.

A*

PNL=percutaneous nephrolithotomy; SWL=shock wave lithotripsy.

Management of stones in patients with neurogenic bladder

Patients with neurogenic bladder are more prone to development of urinary calculi.

In myelomeningocoele patients, latex allergy is common so that appropriate measures need to be taken regardless of the treatment.

Management of stones in transplanted kidneys

Transplanted patients are at additional risk due to their dependency on a solitary kidney, immunsuppresion therapy and possible metabolic impairments.

Stones causing urinary stasis/obstruction require immediate intervention or drainage of the transplanted kidney.

Recommendations

LE

GR

Perform US or NCCT to rule out calculi in patients with transplanted kidneys, unexplained fever, or unexplained failure to thrive (particularly in children).

4

B

Offer patients with transplanted kidneys, any of the contemporary treatment modalities, including shockwave therapy, (flexible) ureteroscopy, and percutaneous nephrolithotomy as management options.

B

Complete metabolic evaluation after stone removal.

A*

*Upgraded following panel consensus.

NCCT=non-contrast enhanced computed tomography;

US=ultrasound.

Special problems in stone removal

Caliceal diverticulum stones

SWL, PNL (if possible) or RIRS.

Can also be removed using laparoscopic retroperitoneal surgery.

Patients may become asymptomatic due to stone disintegration (SWL) whilst well-disintegrated stone material remains in the original position due to narrow caliceal neck.

Horseshoe kidneys

Can be treated in line with the options described above.

Passage of fragments after SWL might be poor.

Acceptable stone-free rates can be achieved with flexible ureteroscopy.

Stones in pelvic kidneys

SWL, RIRS, PNL or laparoscopic surgery.

For obese patients, the options are RIRS, PNL or open surgery.

Patients with obstruction of the ureteropelvic junction

When outflow abnormality requires correction, stones can be removed by PNL together with percutaneous endopyelotomy or open/laparoscopic reconstructive surgery.

URS together with endopyelotomy with Ho:YAG.

Incision with an Acucise balloon catheter might be considered, provided the stones can be prevented from falling into the pyeloureteral incision.

Ho:YAG=holmium:yttrium-aluminium-garnet (laser); PNL=percutaneous nephrolithotomy; SWL=shockwave lithotripsy; URS=ureterorenoscopy; RIRS=retrograde renal surgery.

Management of urolithiasis in children

In children, the indication for SWL and for PNL is similar to those in adults. Compared to adults, children pass fragments more rapidly after SWL. For endourological procedures, the smaller organs in children must be considered when selecting instruments for PNL or URS.

Recommendations

GR

In children, perform PNL for the treatment of renal pelvic or caliceal stones with a diameter > 20 mm (~300 mm2).

C

For intracorporeal lithotripsy, use the same devices as in adults (Ho:YAG laser, pneumatic- and US lithotripters).

C

Ho:YAG holmium:yttrium-aluminium-garnet (laser); PNL=percutaneous nephrolithotomy.

Follow-up

Metabolic evaluation and recurrence prevention

After stone passage, every patient should be assigned to a low- or high-risk group for stone formation. For correct classification, two analyses are mandatory:

Reliable stone analysis by infrared spectroscopy or X-ray diffraction;

Basic analysis.

Only high-risk stone formers require specific metabolic evaluation. Stone type is the deciding factor for further diagnostic tests. For both groups, general preventive measures apply:

General preventive measures

Fluid intake (drinking advice)

Fluid amount: 2.5-3.0 L/day

Circadian drinking

Neutral pH beverages

Diuresis: ≥ 2.5 L/day

Specific weight of urine: < 1010

Nutritional advice for a balanced diet

Balanced diet*

Rich in vegetables and fibre

Normal calcium content: 1-1.2 g/day

Limited NaCl content: 4-5 g/day

Limited animal protein content: 0.8-1.0 g/kg/day

Lifestyle advice to normalize general risk factors

BMI: retain a normal BMI level

Adequate physical activity

Balancing of excessive fluid loss

Caution: The protein need is age-group dependent, therefore protein restriction in childhood should be handled carefully.

*Avoid excessive consumption of vitamin supplements.

Calcium oxalate stones

(Hyperparathyroidism excluded by blood examination)

Recommendations for pharmacological treatment of patients with specific abnormalities in urine composition

Urinary risk factor

Suggested treatment

LE

GR

Hypercalciuria

Thiazide + potassium citrate

1a

A

Hyperoxaluria

Oxalate restriction

2b

A

Enteric hyperoxaluria

Potassium citrate

3-4

C

Calcium supplement

2

B

Diet reduced in fat and oxalate

3

B

Hypocitraturia

Potassium citrate

1b

A

Hypocitraturia

Sodium bicarbonate if intolerant to potassium citrate

1b

A

Hyperuricosuria

Allopurinol

1a

A

Febuxostat

1b

A

High sodium excretion

Restricted intake of salt

1b

A

Small urine volume

Increased fluid intake

1b

A

Urea level indicating a high intake of animal protein

Avoid excessive intake of animal protein

1b

A

No abnormality identified

High fluid intake

2b

B

Figure 3: Diagnostic and therapeutic algorithm for calcium oxalate stones

Figure 4: Diagnostic and therapeutic algorithm for calcium phosphate stones

HPT=hyperparathyroidism; RTA=renal tubular acidosis; UTI=urinary tract infection.

Hyperparathyroidism

Elevated levels of ionized calcium in serum (or total calcium and albumin) require assessment of intact parathyroid hormone to confirm or exclude suspected hyperparathyroidism (HPT). Primary HTP can only be cured by surgery.

Uric acid and ammonium urate stones

Figure 5: Diagnostic and therapeutic algorithm for uric acid- and urate-containing stones

UTI=urinary tract infection.

1 d: day.

2 tid: three times a day.

3 A higher pH may lead to calcium phosphate stone formation.

4 In patients with high uric acid excretion, allopurinol may be helpful.

Figure 6: Metabolic management of cystine stones.

Struvite / infection stones

Recommendations for therapeutic measures of infection stones

LE

GR

Surgically remove the stone material as completely as possible.

3-4

A*

Prescribe a short-term antibiotic course.

3

B

Prescribe a long-term antibiotic course in case of recurrent infections.

3

B

Prescribe ammonium chloride, 1 g, 2 or 3 times daily to ensure urinary acidification.

3

B

Prescribe methionine, 200-500 mg, 1-3 times daily, as an alternative, to ensure urinary acidification.

3

B

Consider prescribing urease inhibitors in case of severe infections (if licensed).

1b

A

*Upgraded following panel consensus

2,8-dihydroyadenine stones and xanthine stones

Both stone types are rare. In principle, diagnosis and specific prevention is similar to that of uric acid stones.

Drug stones

Drug stones are induced by pharmacological treatment. Two types exist:

Stones formed by crystallised compounds of the drug;

Stones formed due to unfavourable changes in urine composition under drug therapy.

Treatment includes general preventive measures and the avoidance of the respective drugs

Investigating a patient with stones of unknown composition

Investigation

Rationale for investigation

Medical history

Stone history (former stone events, family history)

Dietary habits

Medication chart

Diagnostic imaging

Ultrasound in the case of a suspected stone

Unenhanced helical CT

Determination of Hounsfield units provides information on the possible stone composition

Blood analysis

Creatinine

Calcium (ionised calcium or total calcium + albumin)

Uric acid

Urinalysis

Urine pH profile (measurement after each voiding, minimum 4 times daily)

Dipstick test: leukocytes, erythrocytes, nitrite, protein, urine pH, specific weight

Urine culture

Microscopy of urinary sediment (morning urine)

Cyanide nitroprusside test (cysteine exclusion)

Further examinations depend on the results of the investigations listed above.

This short booklet text is based on the more comprehensive EAU Guidelines (978-90-79754-98-4) available to all members of the European Association of Urology at their website, http://www.uroweb.org.

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