Stone disease evaluation in Pathology laboratory: Current prospective.

Dr. Sanjeev Mehta Dr. Sanjeev Mehta MDMD

Metabolic and Renal Stone Analysis : Current prospective

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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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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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Stone Formation : Supersaturation

• k

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Actually up to 65 different chemical compounds are found in urinary calculi.

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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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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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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 CystineUro Lab. 8

24 hrs Urine metabolic profile ; Extensive

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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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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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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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24 hrs Urine metabolic profile graph

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Follow-up in same patient

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Stone analysis

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• 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.

Renal Calculus Analysis

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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.comUro Lab. 17

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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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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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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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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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;8:568AUro Lab. 22

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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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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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%)Uro Lab. 25

Uric Acid

• Hyperuricemia, hyperuricosuria.• Low Urine Ph. < 6.2• Causes:

- Gout.

- Myeloproliferative processes associated with pathological increased purine metabolism.

- Chemotherapy and Radiotherapy.Uro Lab. 26

Rare

Cystine : • Cysteinuria. Acidic• Autosomal recessive disorder.

Xenthene: • Xanthinuria.• Absence of Xanthinooxidase.• Genetic autosomal hereditary recessive

enzyme disorder.

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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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Thank You !Uro Lab. 29