This document discusses metabolic evaluation and stone analysis for kidney stones. It explains that stone analysis identifies the stone composition and underlying causes, which helps determine the appropriate treatment plan. A variety of tests are used, including blood and urine tests, 24-hour urine collection to measure supersaturation levels, and analyzing the stone composition. Integrating the results of these analyses can identify metabolic abnormalities and other factors in 90-95% of cases, guiding personalized medical management and prevention of future stone recurrences.

1. Metabolic and Renal
Stone Analysis : Current
prospective
DDrr.. SSaannjjeeeevv MMeehhttaa MMDD
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2. Stone disease evaluation in
Laboratory
• Series of tests to identify underlying
causes.
1.Identify treatable metabolic abnormality
2.Identify underlying medical disease that
predisposes to stone formation.
3.Outline a treatment plan ; focal
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3. Why Do Kidney Stones Form?
• Reasons: Gnetic/dietary/Environmental
• Urine is supersaturated
• 2009: Supersaturation can be “fix”
• Therefore, our job is to figure out what is
causing the urinary Supersaturation and
How best to fix it!
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4. Stone Formation : Supersaturation
• k
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5. Actually up to 65 different chemical
compounds are found in urinary calculi.
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6. Metabolic evaluation
• Blood and Urinary Tests ; routine
• Stone Analysis
• 24 hrs Urinary Metabolic Profile with
SUPERSATURTION.
New advances in Stone analysis, Blood and
Urinary Chemical analysis can find out 90-95%
cause.*
* Preminger G.M., “Guidelines for medical management of
urolithiasis”, bussin. meet us kid and urol dis,2005
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7. Evaluation : First time stone with
low risk
• Blood screen;
Low K and HCO3, High Chloride - RTA
High Uric acid - gouty diathesis
High Calcium - Pri. Hyperparathyroidism
Low Phosphorus – Renal phosphate leak.
• Stone analysis ; all cases
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8. Evaluation: First time stone
• Urine
Urinalysis : Routine
pH > 7.5 - infection lithiasis
pH < 5.5 - Uric acid lithiasis
Sediments for crystalluria
Urine culture :
Urea-splitting organisms – infection lithiasis.
Screening / quantitative Cystine
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9. 24 hrs Urine metabolic profile ;
Extensive
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10. 24 hrs extensive Metabolic evaluation:
indications
• Stone recurrence
• Motivated patients wants to investigate.
• Select one-time formers:
- Solitary Kidney
- Renal insufficiency.
- Residual stone burden.
• All children
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11. Extensive Metabolic Evaluation
24 hrs Urine collections.
Stone risk factors :
Volume
Calcium , Calcium to creatinine index.
Oxalate . ?Primary hyperoxaluria
Citrate
Uric acid.
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12. Extensive Metabolic Evaluation
• Dietary risk factors:
Sodium,
Potassium
Magnesium
Urinary analytes : phosporus, sulfate, Urea
Marker for accuracy : Creatinine.
Repeat 24 hrs Urine collection 4-6 weeks post
intervantion.
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13. 24 hrs Urine metabolic profile graph
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14. Follow-up in same patient
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15. Stone analysis
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16. Renal Calculus Analysis
• Essential step in the examination and initial
treatment of Urolithiasis.
• Composition yields fundamental information
of pathogenesis of disease like ;
- Metabolic abnormality.
- Presence of infection.
- Possible artifacts.
- Drug metabolism.
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17. Integrated analysis: Techniques
• Optical Crystallogrphy
• Chemical Microscopy.
• Polarizing Microscopy.
• Infrared spectroscopy.
• X-ray diffraction.
• Electron Microscopy
• Fluorescence and chromatography.
• Final , semi quantitative, modified estimate from
above results.
* herringlab.com
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18. Significance of Stone analysis
• Exact composition gives important clue as to
how Stone formed.
• Information may not available from any other
type of work-up.
• Identify factors leading to clinical events.
• Identify Risk factors.
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19. Significance of Stone analysis
Three categories :
1.Composition and hardness of Renal Stones.
2.Composition and its predictive value.
3.Composition and related metabolic
abnormalities.
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20. Hardness Factor of Stone
Calcium Oxalate Dihydrate 1.0
Calcium Oxalate Monohydrate 1.3
Hydroxy-peptite 1.1
Brushite 2.2
Uric Acid/ Urate 1.0
Cystine 2.4
Carbonate Apatite 1.3
Struvite 1.0
Mixed Stone 1.0
* Ringden I, Scand J Urol Nephrol.2007;41(4):316-23
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21. Clinical Significance: Hardness
pattern in Stone.
• Useful in describing consistency in individual.
• Formulation of treatment strategies.
- Number of re-treatments.
- Number of Shock waves.
• Energy index (KV x number of shock waves).
• PMID:17763224( PubMed-indexed for MEDLINE)
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22. Calcium stone….
• Pure Calcium oxalate: More Acid urine, Low
urine volume, high oxalate excretion.
• Mixed Stone formers ;
High Calcium, pH and Stone formation rate.
High Calcium excretion.
* Schroeppel j Smith et all ; J Am Soc Nephrol 1997;8:568A
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23. Calcium…..
• Calcium Oxalate Monohydrate :
Hypomagnesuria, acid urine, low volume
More hard then dihydrate.
• Calcium Oxalate Dihydrate :
- hypercalciuria. High Urine pH and
hypocitraturia.
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24. Calcium Stone with …
Carbonate apatite : may indicate Renal
Tubular Acidosis (RTA).
- Increases with amount of apatite.
( 5 – 39%).
Brushite Stones : Consider Renal tubular
Acidosis (RTA).
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25. Struvite Stones
• Mixed Stone, infection. Mostly Proteus
Ammonium Urate
• Elders : associated with infection.
• Children : May also form as result of
hyperuricosuria, but NO urinary tract
infection.
• Rare in pure form (0.03%)
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26. Uric Acid
• Hyperuricemia, hyperuricosuria.
• Low Urine Ph. < 6.2
• Causes:
- Gout.
- Myeloproliferative processes associated
with pathological increased purine
metabolism.
- Chemotherapy and Radiotherapy.
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27. Rare
Cystine :
• Cysteinuria. Acidic
• Autosomal recessive disorder.
Xenthene:
• Xanthinuria.
• Absence of Xanthinooxidase.
• Genetic autosomal hereditary recessive
enzyme disorder.
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28. Conclusion.
• Combined with Optical Crystallography,
appropriate Blood & 24 Urine metabolic
work-up with super-saturation, it can find
out the cause of stone formation in nearly
all cases
• Supersaturation Index is GOLD Standard to
know exactly patho-physiological basis of
Stone formation to guide proper treatment.
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29. Thank You !
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