Nep_727.fm

nep_727.fm Page 31 Friday, January 26, 2007 6:34 PM Blackwell Publishing AsiaMelbourne, AustraliaNEPNephrology1320-5358 2006 The Author; Journal compilation 2006 Asian Pacific Society of Nephrology200712S13133MiscellaneousKidney StonesThe CARI Guidelines NEPHROLOGY 2007; 12, S31–S33
Metabolic evaluation
GUIDELINES
No recommendations possible based on Level I or II evidence
SUGGESTIONS FOR CLINICAL CARE
suspected acute renal colic. See the imaging guideline for
further information.
(Suggestions are based on Level III and IV evidence) • Stone analysis if possible
Suggestions are based on opinion and other guidelines.
• Consider urinary cystine if stone composition
Clinical assessment is important to determine whether
stones might be secondary to gastrointestinal disorders
• Parathyroid hormone in those with hypercalcaemia
(i.e. malabsorption, Crohn’s disease or following surgical
For recurrent stone formers or complicated stone disease:
bowel resection or bypass), other medical conditions (e.g.
• Blood uric acid
sarcoidosis) or medications (e.g. indinavir, triamterene).
• 24 h urine – volume, creatinine, calcium, uric acid, ox-
The investigations suggested below are to help to detect
alate, citrate, cystine (other possible tests include sodium,
other important secondary causes of stones (e.g. hyper-
potassium, magnesium, phosphate, chloride and urea).
calcaemia, urinary infection) and possible complications
of stones (e.g. impaired kidney function).
Extensive investigations have not been recommended
BACKGROUND
in people presenting with their first stone as these are
People who form kidney stones require investigations to unlikely to change management. Urinary metabolic test-
identify underlying medical conditions and to detect other ing can be performed in people who are being considered
predisposing metabolic abnormalities. The results of these for prophylactic medical therapy, if the therapy is to be
investigations can also be used to help guide therapy to pre- tailored to the specific abnormality found. This includes
vent future stone formation. The extent of testing required those who are forming recurrent stones and others who
depends on several factors including age and medical history are at high risk of complications if they develop further
of the person and the number and frequency of stones. This stones (e.g. single kidney or renal impairment). In people
guideline aims to provide a brief review of available evi- presenting with idiopathic stones (i.e. no identifiable
dence regarding which investigations are required to assist underlying medical condition such as infection stones,
in the management of people with kidney stones. This is malabsorption, cystinuria, etc.), metabolic testing does
supplemented with the Suggestions for Clinical Care not appear to be able to accurately predict who will go on
section and recommendations from other international to develop stones in the future.
There is limited evidence that metabolic testing should
be deferred for at least 3 months after an episode of acute
renal colic in order to allow dietary and fluid intake to
SEARCH STRATEGY
return to normal, allowing more accurate assessment of
any abnormalities.1
Databases searched: Medline (1966 to July Week 3, 2004).
Following is the formation of a single stone:
MeSH terms and text words for kidney stones were com- • Blood – electrolytes, bicarbonate, urea, creatinine,
bined with MeSH terms and text words for metabolic work- up (e.g. serum calcium, serum phosphate, pH level, etc.).
• Spot urine – pH, blood, leucocytes, microscopy, culture
The results were then combined with the Cochrane search • Imaging – can use x-ray, ultrasound or CT. Unen-
strategy for cohort and prognostic studies.
hanced helical CT is the imaging modality of choice for
Date of searches: 17 January 2005.
WHAT IS THE EVIDENCE?
Correspondence: Dr Peter Hughes, Department of Nephrology, No trials have studied which investigations are required in Royal Melbourne Hospital, Grattan Street, Parkville VIC 3050, first-time stone formers in order to detect underlying or con- 2007 The AuthorJournal compilation 2007 Asian Pacific Society of Nephrology nep_727.fm Page 32 Friday, January 26, 2007 6:34 PM Several randomized controlled trials of medical therapies European Association of Urology, Working Party on
have only included recurrent stone formers with specific Lithiasis19
metabolic abnormalities (e.g. hypercalcaemia, hyperurico- • Stone composition in every patient
suria). Therefore, quantification of these parameters is • Blood – calcium, albumin, creatinine, ± uric acid
required if people are to be treated according to the results • Early morning sputum
of these trials (see Guidelines for each stone type for trial • Dipstick pH, leucocytes, bacteria
• Culture if bacteria
The value of metabolic testing to give prognostic infor- • Cystine test if cystinuria not excluded by other means
mation has been studied in a number of studies. In retro- • Complicated stone formers – 24 h urine for calcium,
spective studies, people who form stones are more likely to oxalate, citrate, urate, creatinine, volume, magnesium, have urinary metabolic abnormalities (e.g. hypercalcuria)2–7 phosphate, urea, sodium, chloride, potassium and those who form recurrent stones tend to have more significant metabolic abnormalities than those with single stones.7–13 Furthermore, those who have improvement in IMPLEMENTATION AND AUDIT
urinary metabolic abnormalities during therapy are less likely to develop subsequent stones.14 However, in prospec- tive studies of people presenting with kidney stones, the overlap in the urinary metabolic results is so great that those SUGGESTIONS FOR FUTURE RESEARCH
who will go on to develop stones in the future cannot prospectively be separated from those who will not.9,15,16 Interpretation of urinary metabolic results is further complicated by the fact that many results are continuous variables and the distinction between normal and abnormal CONFLICT OF INTEREST
is arbitrary. This can mean that many normal people with- Peter Hughes has no relevant financial affiliations that out a history of stones have abnormal urinary results.4,17 would cause a conflict of interest according to the conflict of Furthermore, people with previous stones whose urinary interest statement set down by CARI.
excretion of several salts is high in the normal range can be at significant risk of recurrent stones.7 REFERENCES
SUMMARY OF THE EVIDENCE
1. Norman RW, Bath SS, Robertson WG et al. When should patients with symptomatic urinary stone disease be evaluated metaboli- There are no randomized controlled trials on this topic.
cally? J. Urol. 1984; 132: 1137–9.
2. Wasserstein AG, Stolley PD, Soper KA et al. Case–control study of risk factors for idiopathic calcium nephrolithiasis. Miner Elec- WHAT DO THE OTHER GUIDELINES SAY?
trolyte Metab. 1987; 13: 85–95.
3. Leonetti F, Dussol B, Berthezene P et al. Dietary and urinary risk Kidney Disease Outcomes Quality Initiative: No
factors for stones in idiopathic calcium stone formers compared with healthy subjects. Nephrol. Dial. Transplant. 1998; 13: 617–22.
UK Renal Association: No recommendation.
4. Curhan GC, Willett WC, Speizer FE et al. Twenty-four-hour urine Canadian Society of Nephrology: No recommendation.
chemistries and the risk of kidney stones among women and men.
European Best Practice Guidelines: No recommendation.
Kidney Int. 2001; 59: 2290–98.
5. Strazzullo P, Gianvincenzo B, Vuotto P et al. Past history of neph- rolithiasis and incidence of hypertension in men: A reappraisalbased on the results of the Olivetti Prospective Heart Study. Neph- INTERNATIONAL GUIDELINES
rol. Dial. Transplant. 2001; 16: 2232–5.
6. Cirillo M, Stellato D, Panarelli P et al. Cross-sectional and pro- National Institutes of Health Kidney Stones Consensus
spective data on urinary calcium and urinary stone disease. Kidney Conference:18
Int. 2003; 63: 2200–206.
• Collect and analyse the stone in all patients
7. Robertson WG. A risk factor model of stone-formation. Front. • Urinalysis; culture if clinically indicated
Biosci. 2003; 8: S1330–38.
• Blood electrolytes, creatinine, calcium, phosphate,
8. Strauss AL, Coe FL, Deutsch L et al. Factors that predict relapse of calcium nephrolithiasis during treatment. A prospective study.
• Urinary cystine if stone composition is unknown
Am. J. Med. 1982; 72: 17–24.
• Parathyroid hormone (PTH) in hypercalcaemic patients
9. Ljunghall S, Danielson BG. A prospective study of renal stone • Kidney ureter bladder x-ray (KUB) and intravenous pyel-
recurrences. Br. J. Urol. 1984; 56: 122–4.
10. Cupisti A, Morelli E, Lupetti S et al. Low urine citrate excretion as ography in all patients unless contraindicated main risk factor for recurrent calcium oxalate nephrolithiasis in • In recurrent stone formers (and all children), additional
males. Nephron 1992; 61: 73–6.
investigations should include a 24 h urine test for volume, 11. Di Silvero F, D’Angelo AR, Gallucci M et al. Incidence and pre- pH, calcium, phosphorus, sodium, uric acid, oxalate, citrate diction of stone recurrence after lithotripsy in idiopathic calcium stone patients: A multivariate approach. Eur. Urol. 1996; 29: 41–6.
nep_727.fm Page 33 Friday, January 26, 2007 6:34 PM 12. Yagisawa T, Chandhoke PS, Fan J. Metabolic risk factors in 16. Siener R, Glatz S, Nicolay C et al. Prospective study on the patients with first-time and recurrent stone formations as deter- efficiency of a selective treatment and risk factors for relapse in mined by comprehensive metabolic evaluation. Urology 1998; 52:
recurrent calcium oxalate stone patients. Eur. Urol. 2003; 44:
13. Tiselius HG. Factors influencing the course of calcium oxalate 17. Curhan GC, Willett WC, Speizer FE et al. Intake of vitamins B6 stone disease. Eur. Urol. 1999; 36: 363–70.
and C and the risk of kidney stones in women. J. Am. Soc. Neph- 14. Tiselius HG, Sandvall K. How are urine composition and stone rol. 1999; 10: 840–45.
disease affected by therapeutic measures at an outpatient stone 18. Consensus Conference. Prevention and treatment of kidney clinic? Eur. Urol. 1990; 17: 206–12.
stones. JAMA 1988; 260: 977–81.
15. Trinchieri A, Ostini F, Nespoli R et al. A prospective study of 19. Tiselius HG, Ackermann D, Alken P et al. Working Party on Lith- recurrence rate and risk factors for recurrence after a first renal iasis, European Association of Urology. Guidelines on urolithiasis.
stone. J. Urol. 1999; 162: 27–30.
Eur. Urol. 2001; 40: 362–71.

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