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How to diagnose, treat and prevent kidney stones

Thomas Knoll 
and Christian T
17 June, 2011  

Thomas Knoll
Head and Chairman
, Department of Urology, Sindelfingen-Boeblingen Medical Centre, University of Tübingen, Germany

Christian Türk

Department of Urology Krankenanstalt Rudolfstift, Vienna, Austria



On behalf of the EAU Working Group on Urolithiasis. The working group consists of the following panel members: C. Türk, Vienna, Austria (chairman); T. Knoll, Sindelfingen, Germany (vice-chairman); A. Petrik, Budjovice, Czech Republic; K. Sarica, Istanbul, Turkey; C. Seitz, Vienna, Austria; M. Straub, Munich, Germany; O. Traxer, Paris, France.

These guidelines are based on regular, structured literature searches, Cochrane reviews and expert consensus. The complete guideline is available on www.uroweb.org.1

Diagnosis and treatment
Diagnosis
Routine diagnostic measures should include 
classification of the type of stone former, identification of risk factors for stone formation, imaging, analysis of stone size and composition and standard biochemical investigation (kidney function, urine analysis).

The best modality for imaging remains under discussion, ultrasound and excretory urography have been the standard for decades. However, unenhanced computed tomography (CT) became the standard in many hospitals because of its high sensitivity, the fast diagnosis and its ability to work without contrast agent.

Drawbacks are the higher radiation exposure and the lack of general availability. Furthermore, one of the advantages of excretory urography is the additional information it provides on renal function and anatomy of the renal collecting 
system.

Acute management
The patient with an acute colic requires immediate pain medication. Non-steroidal anti-inflammatory drugs (NSAIDs) have excellent efficacy (i.e. diclofenac sodium, indomethacin, ibuprofen). If pain persists, morphine might become necessary. A conservative strategy based on pain medication and supportive medication for spontaneous stone passage (i.e. tamsulosin) is possible if symptoms are well controlled and risk factors – such as fever, urinary tract infection (UTI) and renal insufficiency – are absent (see Table 1).

Placement of a DJ-stent or a percutaneous nephrostomy is recommended when pain relief cannot be achieved or medical reasons like urosepsis or renal failure demand urinary drainage.

Active stone removal
The following procedures are recommended if the stones do not pass or when medical reasons demand active stone removal:

  • 
Extracoroporal shockwave lithotripsy (ESWL)
  • Ureteroscopy (URS)
  • Percutaneous nephrolithotomy (PCNL)
  • Chemolysis
  • Open or laparoscopic surgery.

Today, open or laparoscopic procedures are limited to very selected cases. Oral chemolysis can be offered to patients with radiolucent uric acid stones. The principle is elevation of urine pH into a range of 7.0–7.4 by intake of citrate or sodium bicarbonate.

Kidney stone removal
The standard treatment for renal stones is the application of ESWL (see Table 2). PCNL is recommended as first-line treatment when stone size exceeds 20mm because of its excellent stone free rate that is independent from stone burden (Table 3). The value of retrograde kidney stone removal (flexible URS) is discussed. Based on the available literature, it is recommended as a second-line procedure.

Lower renal pole
A special situation in active stone removal remains the lower renal pole. Due to its special spatial anatomy, stone clearance after ESWL is more difficult, with reported stone free rates from 20-80%. Therefore, percutaneous treatment is recommended from stone sizes of 15mm upwards. For smaller stones, several publications reported excellent stone free rates for flexible URS. However, an analysis of the available evidence still suggests ESWL as first-line therapy of such stones.

Ureteral stone removal
The EAU working group performed a joint guideline project together with the Urolithiasis Guideline Panel of the American Urological Association (AUA) for ureteral calculi.2,3 As with kidney stones, ESWL and URS are the standard treatment options when medical expulsion therapy was unsuccessful or not indicated. Again, open or laparoscopic surgery is only an option for selected cases.

Based on the available literature, ESWL lost it traditional rank as the first-line therapy of ureteral calculi. With the introduction of smaller endoscopes, improved video technique, intracorporal laser lithotripsy and latest stone extraction tools, URS became the preferred treatment option for many urologists. Even though the overall stone free rate of URS and ESWL seem to be comparable, URS achieves complete stone clearance after fewer procedures and shorter treatment time. However, it is more invasive and requires general anaesthesia.

Management of special problems
Most guideline recommendations are focused on index patients. However, special situations regularly occur in clinical routine and treatment algorithms have to be tailored individually. Such special situations include stones during pregnancy, in children, infection stones, cystine stones or special medical problems (e.g. patients on anticoagulation). Anatomic variations such as horseshoe or pelvic kidney may further complicate the treatment. As space in this article is limited, the interested reader is referred to the online versions of the guideline for further information.

Prevention
Urinary stone disease is common, affecting one in ten people in Europe. However, only a smaller portion of this group (25%) is at high risk of recurrent stone formation. It is therefore desirable to identify this high-risk group. Comprehensive metabolic evaluation, diet and methods of medical stone prevention can reduce the frequency of stone recurrences and associated medical problems.

High-risk patients are those with more than two recurrences, single kidney or impaired renal function, all stone compositions apart from calcium oxalate, inflammatory bowel disease or bowel surgery, hyperparathyroidism, genetic disorders (e.g. cystinuria or renal tubular acidosis), and children.

Extended evaluation in these patients should include analysis of lifestyle, drinking and dietary habits, two 24-hour urine analyses and biochemical analysis (see Tables 4 and 5). It is important to mention that these patients have to be followed up regularly.

Medical prevention therapy is mainly based on urine pH modification. This involves pH elevation for all stone compositions except for infection stones, where pH has to be lowered. Elevation of pH can be achieved by oral alkaline citrate or sodium bicarbonate application. The patient has to measure his urine pH and to modify the medication to keep it within the desired range (see Table 6 and the complete guideline document for more information).

References

  1. 
Tiselius HG et al. Eur.Urol. 2001;40(4):362.
  2. 
Preminger GM et al. Eur Urol. Dec 2007;52(6):1610-1631.
  3. 
Preminger GM et al. J Urol. Dec 2007;178(6):2418-2434.