Urinary Stone disease : Metabolic work up and its significaance

Dr. Sanjeev Mehta Dr. Sanjeev Mehta MDMD

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Metabolic Work-up of Urinary Stone Disease and its significance.

Stone disease: issues

High IncidenceRecurrence Underlying abnormalityResearch

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Stone Formation : Supersaturation

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Super saturation drives crystal formation and growth

Stone disease treatment ?

Objective to treat disease ;• To make Patient free of disease.• To stop recurrence of same disease. Does current therapy address recurrence

issue ? Right approach and treatment is Right approach and treatment is possible once exact cause is known. possible once exact cause is known.

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Work-up : Series of tests

1.Identify treatable metabolic abnormality2.Identify underlying medical disease that

predisposes to stone formation.3.Outline a treatment plan. STONE ANALYSIS.24 HRS URINE METABOLIC PROFILENew advances in Stone analysis, Blood and Urinary

Chemical analysis can find out 90-95% cause.

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Six myths

1. All stones are Calcium stones.2. Composition can be diagnosed by looking to

stone.3. Doesn’t affect treatment /prognosis.4. Once stone analysis done, no need to repeat. 5. Expensive. 6. Small fragments can’t be analysed.

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• “On both Clinical and Economic grounds, evidence based medical intervention is the only approach likely to make a significant impact on the incidence, and on recurrence of disease.”*

• Targeted medical prophylaxis requires reliable information on stone type.

*Ref: Ann Clin biochem 2004;41:91-97

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Stone Evaluation : Why ?

Stone analysis

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Renal Stone Analysis

• Essential step in the examination and initial treatment of Urolithiasis.

• Composition yields fundamental information of pathogenesis of disease like ;- Metabolic abnormality.- Etiological diagnosis . - Presence of infection.- Possible artifacts.- Drug metabolism.

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Actually up to 100 different chemical compounds are found in urinary calculi.

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Fractured Stone...

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INTEGRETED ANALYSIS;Mixed Stone

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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.• Subsequent analysis differ in 21% cases,

making it to analyse with every episode

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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 1.0Calcium Oxalate Monohydrate 1.3Hydroxy-peptite 1.1Brushite 2.2Uric Acid/ Urate 1.0Cystine 2.4Carbonate Apatite 1.3Struvite 1.0Mixed Stone 1.0* Ringden I, Scand J Urol Nephrol.2007;41(4):316-23

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Stone analysis: Exclusive and only way :

• Cystine • Xenthine • 2,8, - dihydroxyademine• Drugs - Sulfadiazine-- Atazanavir- Triemterene , anti viral drug• Artefacts

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Stones: Specific treatment

• Uric acid stones ; treatable if pure • Cystine stones. • Struvite stones . • Xenthine stones. • Drug stones.• 2,8 dihydroxyadenine stones. • Silicate stone

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Screen for systemic diseases

• Stone is first manifestation of numerous disorders.

• Hyperparathyroidism• Primary hyperoxaluria.• Distal renal tubular acidosis• Medullary sponge kidney. • Crohn's disease, Bariatric surgery.

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Calcium Stones

• Commonest ; Pure or mixed. • Mixed stones can have more than two

components• Each component gives clue about cause • Phosphate component, more challenging to

treat.• With 24 hrs Urine metabolic profile; best

results

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Idiopathic Calcium stones

Calcium Oxalate Monohydrate

Calcium Oxalate Dihydrate

Hyper-oxaluria 88% Hyper-calciuria 85%Hypo magnesuria Hypocitruria Acidic Urine Alkaline UrineLow Urine volume Low Urine VolumeHard ++ Hard +

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Ammonium Urate

• Calcium oxalate – containing calculi, may start due to hyperuricosuria.

• 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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Phosphate Stones

• 12 to 20%

• Struvite : Infection. • Carbonate Apatite : Not always infection.• Brushite : Not associated with infection

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Phosphate Stones; Carbonate apatite

• CaOx stones contain CaPh component due to Randall’s plaque.

• With COD raises suspicion of Pri. Hyperparathyroidism.

• Higher apatite suggests RTA• Have high pH. ? Infection • Infection; presence of Struvite confirms ; carbonate > 15% HCL test.

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Initial nucleation process could be related to another pathology

mixed with Magnesium ammonium phosphate. • Cystine in initial analysis : secondary UTI• Cystine or uric acid initially ; over enthusiastic

alkali therapy • Uric acid to xenthine due to allopurinol

therapy.

Composition can change !

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24 hrs Urine metabolic profile ;

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24 hrs Urine Metabolic Test profile • Oxalate• Citrate• Uric acid• Sodium • Potassium • Magnesium • Phosphorus• Creatinine• pH• Total volume

• Super-saturation - Calcium oxalate- Calcium Phosphate -Uric Acid.

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Prevention can be achieved!

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Prevention: five steps

1. Know your crystals2. Obtain proper blood and 24 hrs Urine

measurements3. Lower by half the Supersaturation. 4. Obtain more 24 hrs Urines if new stone continue5. Follow up every year thereafter even if free of

new stones.Fredric Co;http://kidneystones.uchicago.edu/

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Thank You !Uro Lab. 30