Kidney Stones: An Overview Gerald Da Roza MD, MHSc, FRCPC March 15, 2010

Kidney Stones: Kidney Stones: An OverviewAn Overview

Gerald Da RozaGerald Da Roza

MD, MHSc, FRCPCMD, MHSc, FRCPC

March 15, 2010March 15, 2010

OverviewOverview

CaseCase Diagnosis of kidney stonesDiagnosis of kidney stones Acute managementAcute management EpidemiologyEpidemiology Risk factorsRisk factors Work up and treatmentWork up and treatment Diet and kidney stonesDiet and kidney stones

Case – A Few Years AgoCase – A Few Years Ago

30 year old nephrology fellow30 year old nephrology fellow Bright, hardworking, drivenBright, hardworking, driven Atrocious diet (hospital cafeteria and Atrocious diet (hospital cafeteria and

vending machines, no fruit and vegetables, vending machines, no fruit and vegetables, ++ salt)++ salt)

Drinks very little during daytimeDrinks very little during daytime Presents with acute onset of R Presents with acute onset of R

costovertebral pain, radiating around to costovertebral pain, radiating around to anterior abdomen, 10/10 in severity, anterior abdomen, 10/10 in severity, nauseau and vomitingnauseau and vomiting

Case – A Few Years AgoCase – A Few Years Ago

Physical ExamPhysical Exam Tachycardia, normotensive, afebrileTachycardia, normotensive, afebrile ++ CVA and RUQ tenderness++ CVA and RUQ tenderness Nil elseNil else

InvestigationsInvestigations U/A shows hematuria, U/A shows hematuria, CBC, lytes urea, Cr normalCBC, lytes urea, Cr normal

Diagnosis???Diagnosis???

Kidney Stone - Why?Kidney Stone - Why? DDxDDx

Renal Cell Ca w/ blood clotRenal Cell Ca w/ blood clot Renal Cyst w/ clotRenal Cyst w/ clot PyelonephritisPyelonephritis AAA/dissectionAAA/dissection Ectopic Pregnancy (if female)Ectopic Pregnancy (if female) Intestinal ObstructionIntestinal Obstruction AppendicitisAppendicitis

How do we make the How do we make the diagnosis?diagnosis?

Investigative Options:Investigative Options: CT ScanCT Scan USUS Abdominal Plain FilmAbdominal Plain Film MRIMRI IVPIVP

Non-contrast Helical CT Non-contrast Helical CT ScanScan

Gold standardGold standard Sensitivity 95 %, Specificity 98% Sensitivity 95 %, Specificity 98%

Dual energy CT (DECT) is new imaging Dual energy CT (DECT) is new imaging modality may be able to predict stone modality may be able to predict stone composition (future tx)composition (future tx)

Helps determine if obstruction present Helps determine if obstruction present Provides alternate diagnosis in many casesProvides alternate diagnosis in many cases

33 percent had an alternate diagnosis not suspected 33 percent had an alternate diagnosis not suspected on clinical grounds, one-half of whom had significant on clinical grounds, one-half of whom had significant disease disease

Only misses stones due to protease inhibitorsOnly misses stones due to protease inhibitors

CT KUBCT KUB

UltrasoundUltrasound

Procedure of choice for pts who should Procedure of choice for pts who should avoid radiationavoid radiation pregnant women and possibly women of pregnant women and possibly women of

childbearing agechildbearing age Sensitive for the diagnosis of obstructionSensitive for the diagnosis of obstruction Can detect radiolucent stones missed on Can detect radiolucent stones missed on

x-rayx-ray May miss small stones and ureteral May miss small stones and ureteral

stones stones

UltrasoundUltrasound

Abdominal X-rayAbdominal X-ray

will identify sufficiently large will identify sufficiently large radiopaque stonesradiopaque stones calcium, struvite, and cystine stonescalcium, struvite, and cystine stones

will miss radiolucent uric acid stoneswill miss radiolucent uric acid stones may miss small stones or stones may miss small stones or stones

overlying bony structuresoverlying bony structures will not detect obstructionwill not detect obstruction

OtherOther

Intravenous Pyelogram (IVP)Intravenous Pyelogram (IVP) higher sensitivity and specificity than plain film for higher sensitivity and specificity than plain film for

thethe provides data about the degree of obstruction provides data about the degree of obstruction previously the diagnostic procedure of choice, no previously the diagnostic procedure of choice, no

longer because of potential contrast rxn, lower longer because of potential contrast rxn, lower sens, higher radiation sens, higher radiation

Magnetic resonance imagingMagnetic resonance imaging rarely used during the management of stone rarely used during the management of stone

disease, except in the evaluation of pregnant disease, except in the evaluation of pregnant patients, because this modality is not optimal for patients, because this modality is not optimal for identifying stones. identifying stones.

Acute ManagementAcute Management

Many pts with acute renal colic can be Many pts with acute renal colic can be managed conservatively with pain managed conservatively with pain medication (NSAIDs & Opiods) and medication (NSAIDs & Opiods) and hydration until the stone passes hydration until the stone passes

If able to take oral medications and If able to take oral medications and fluids can manage at homefluids can manage at home

Hospitalization required for those who Hospitalization required for those who cannot tolerate oral intake or who cannot tolerate oral intake or who have uncontrollable pain or feverhave uncontrollable pain or fever


Pts instructed to strain their urine Pts instructed to strain their urine for several days and bring in any for several days and bring in any stone that passes for analysisstone that passes for analysis will enable clinician to better plan will enable clinician to better plan

preventive therapypreventive therapy Data suggests faster stone passage Data suggests faster stone passage

tamsulosintamsulosin CCB is other optionCCB is other option

Pts are re-imaged if spontaneous Pts are re-imaged if spontaneous passage has not occurred. passage has not occurred.


Urgent urologic consultation Urgent urologic consultation warranted in:warranted in: UrosepsisUrosepsis Acute renal failureAcute renal failure AnuriaAnuria Unyielding pain, nausea, or vomiting Unyielding pain, nausea, or vomiting

Acute ManagementAcute Management Stone size major determinant of the Stone size major determinant of the

likelihood of spontaneous stone passage, likelihood of spontaneous stone passage, although stone location is also importantalthough stone location is also important Most stones ≤4 mm in diameter pass Most stones ≤4 mm in diameter pass

spontaneously. For stones larger than 4 mm spontaneously. For stones larger than 4 mm in diameter, there is a progressive decrease in diameter, there is a progressive decrease in the spontaneous passage rate, which is in the spontaneous passage rate, which is unlikely with stones ≥10 mm in diameterunlikely with stones ≥10 mm in diameter

Proximal ureteral stones are also less likely Proximal ureteral stones are also less likely to pass spontaneously. to pass spontaneously.


Referral to urology for potential Referral to urology for potential interventionintervention stones larger than 10 mm in diameterstones larger than 10 mm in diameter significant discomfortsignificant discomfort significant obstruction or who have not significant obstruction or who have not

passed the stone after four to six weekspassed the stone after four to six weeks

Urologic OptionsUrologic Options Shock wave lithotripsy (SWL)Shock wave lithotripsy (SWL)

tx choice in 75% ptstx choice in 75% pts works best for stones in renal pelvis and upper works best for stones in renal pelvis and upper

ureterureter Ureteroscopic lithotripsy with Ureteroscopic lithotripsy with

electrohydraulic or laser probeselectrohydraulic or laser probes higher stone-free rates, but with an increased higher stone-free rates, but with an increased

incidence of complications over shock wave incidence of complications over shock wave lithotripsylithotripsy

Percutaneous nephrolithotomyPercutaneous nephrolithotomy Laparoscopic stone removalLaparoscopic stone removal

Rarely neededRarely needed

Kidney Stones - Kidney Stones - EpidemiologyEpidemiology

Renal stones (nephrolithiasis) are a Renal stones (nephrolithiasis) are a relatively common problemrelatively common problem

In US, up to 12% of men and 5% of In US, up to 12% of men and 5% of women will have at least one women will have at least one symptomatic stone by the age of 70 symptomatic stone by the age of 70

Clinical PresentationsClinical Presentations

Classic SxClassic Sx Renal ColicRenal Colic Hematuria (gross or microscopic in Hematuria (gross or microscopic in

majority if symptoms but not all)majority if symptoms but not all) Atypical SxAtypical Sx

Vague abdominal pain, nausea, urinary Vague abdominal pain, nausea, urinary urgency or frequency, difficulty urgency or frequency, difficulty urinating, penile pain, or testicular urinating, penile pain, or testicular pain. pain.

AsymptomaticAsymptomatic

Renal ColicRenal Colic

Varies from a mild and barely noticeable ache Varies from a mild and barely noticeable ache to discomfort that is so intense that requires to discomfort that is so intense that requires parenteral analgesicsparenteral analgesics

typically waxes and wanes in severity, and typically waxes and wanes in severity, and develops in waves or paroxysms that are develops in waves or paroxysms that are related to movement of the stone in the ureter related to movement of the stone in the ureter and associated ureteral spasm.and associated ureteral spasm.

Paroxysms of severe pain usually last 20 to 60 Paroxysms of severe pain usually last 20 to 60 minutesminutes

Pain is thought to occur primarily from urinary Pain is thought to occur primarily from urinary obstruction with distention of the renal capsule. obstruction with distention of the renal capsule.

Stone CompositionStone Composition

80% are Calcium Stones80% are Calcium Stones Calcium Oxalate (majority)Calcium Oxalate (majority) Calcium Phosphate (Hydroxapetite Calcium Phosphate (Hydroxapetite

stones)stones)

Stone Composition Stone Composition Uric acidUric acid Struvite (magnesium ammonium phosphate) Struvite (magnesium ammonium phosphate)

only form in pts with chronic upper UTI d/t urease-only form in pts with chronic upper UTI d/t urease-producing organism: Proteus or Klebsiella producing organism: Proteus or Klebsiella

Cystine stonesCystine stones only develop in pts with cystinuria (an AR disorder) only develop in pts with cystinuria (an AR disorder)

due to the poor solubility of cystine in the urine due to the poor solubility of cystine in the urine Mixed stone (eg, calcium oxalate and uric acid)Mixed stone (eg, calcium oxalate and uric acid) Other: indinavir, sulfadiazine, triamterene, Other: indinavir, sulfadiazine, triamterene,

acyclovir stoneacyclovir stone

Risk Factors for StonesRisk Factors for Stones

HistoricalHistorical AnatomicAnatomic DietaryDietary Urinary Urinary

Historical Risk FactorsHistorical Risk Factors

Prior History of Kidney StonesPrior History of Kidney Stones 50% recurrence in 10 yrs50% recurrence in 10 yrs

Family History of kidney stonesFamily History of kidney stones Twofold increase by Health professionals studyTwofold increase by Health professionals study

Individuals with enhanced enteric oxalate Individuals with enhanced enteric oxalate absorptionabsorption gastric bypass procedures, bariatric surgery, gastric bypass procedures, bariatric surgery,

short bowel syndrome short bowel syndrome Frequent upper urinary tract infectionsFrequent upper urinary tract infections Excessive physical exertionExcessive physical exertion

Historical RFHistorical RF

Medical conditions assoc w/ stones:Medical conditions assoc w/ stones: Primary Hyperparathyroidism, SarcoidosisPrimary Hyperparathyroidism, Sarcoidosis Gout, Obesity, DM (concentrated acidic Gout, Obesity, DM (concentrated acidic

urine)urine) HTNHTN RTARTA

Use of medications that may crystallize Use of medications that may crystallize urineurine Indinavir, acyclovir, sulfadiazine, Indinavir, acyclovir, sulfadiazine,

triamterene triamterene

Anatomic RFAnatomic RF

Medullary sponge kidneyMedullary sponge kidney Horseshoe kidneyHorseshoe kidney

Medullary Sponge Medullary Sponge KidneyKidney

Horseshoe KidneyHorseshoe Kidney

Dietary Risk FactorsDietary Risk Factors

? Low or High ?? Low or High ? CalciumCalcium FluidsFluids OxalateOxalate Protein Protein SaltSalt SucroseSucrose


Low Calcium IntakeLow Calcium Intake increases absorption & excretion of increases absorption & excretion of

oxalate d/t less complexing with oxalate d/t less complexing with calcium in the intestinal lumen calcium in the intestinal lumen

Low fluid intakeLow fluid intake Higher concentration of lithogenic Higher concentration of lithogenic

factors in urinefactors in urine Low potassiumLow potassium Low phytateLow phytate


High oxalate intakeHigh oxalate intake High animal protein intakeHigh animal protein intake

leads to hypercalciuria, hyperuricosuria, leads to hypercalciuria, hyperuricosuria, hypocitraturia, and inc urinary acid excretionhypocitraturia, and inc urinary acid excretion

High sodium intake High sodium intake High sucrose intakeHigh sucrose intake

may increase calcium and/or oxalate may increase calcium and/or oxalate excretion excretion

High Vitamin C IntakeHigh Vitamin C Intake

Urinary Risk Factors Urinary Risk Factors

Low volumeLow volume HypercalcuriaHypercalcuria HyperoxaluriaHyperoxaluria HypocitraturiaHypocitraturia Extremes of pHExtremes of pH

pH greater than 7.5 is compatible with infection pH greater than 7.5 is compatible with infection pH less than 5.5 favours uric acid lithiasis. pH less than 5.5 favours uric acid lithiasis.

Urine culture +ve urease-producing Urine culture +ve urease-producing organism (struvite)organism (struvite) Proteus or Klebsiella Proteus or Klebsiella

Work Up & TreatmentWork Up & Treatment

Controversial whether evaluation and Controversial whether evaluation and therapy warranted or cost effective therapy warranted or cost effective after the first stone or only in patients after the first stone or only in patients with: with: Active stone diseaseActive stone disease

formation of new stones, increase in size of formation of new stones, increase in size of old stones, or the continued passage of old stones, or the continued passage of gravel gravel

Multiple stones at first presentationMultiple stones at first presentation Pts with a strong family history of stonesPts with a strong family history of stones

ApproachesApproaches

Limited EvaluationLimited Evaluation Targeted EvaluationTargeted Evaluation

base the extent of evaluation upon an base the extent of evaluation upon an estimation of the risk for new stone estimation of the risk for new stone formationformation

Complete EvaluationComplete Evaluation approach should be followed only in approach should be followed only in

individuals willing to make dietary individuals willing to make dietary changes or to take medical therapy if changes or to take medical therapy if warranted by the work-up. warranted by the work-up.

Complete EvaluationComplete Evaluation CBC, lytes, bicarbonate, urea, creatinineCBC, lytes, bicarbonate, urea, creatinine Calcium, phosphorus, PTH, uric acidCalcium, phosphorus, PTH, uric acid Urinalysis for pH and crystalsUrinalysis for pH and crystals 24-hr urine: volume, calcium, uric acid, 24-hr urine: volume, calcium, uric acid,

citrate, oxalate, sodium, and creatininecitrate, oxalate, sodium, and creatinine At least two 24-hour urine collections At least two 24-hour urine collections while pt maintains usual diet and physical activitieswhile pt maintains usual diet and physical activities wait at least one to three months after a stone wait at least one to three months after a stone

eventevent should not be performed if renal/ureteral should not be performed if renal/ureteral

obstruction or urinary tract infection from existing obstruction or urinary tract infection from existing calculi. calculi.

Treatment of Kidney Treatment of Kidney StonesStones

General treatment strategies for all General treatment strategies for all stone formersstone formers

Specific treatment strategy is based Specific treatment strategy is based on: on: stone composition if available (assume stone composition if available (assume

calcium if not most of the time)calcium if not most of the time) findings from metabolic evaluationfindings from metabolic evaluation Patient dietary patternsPatient dietary patterns

General TreatmentGeneral Treatment

Increase fluid intake to target u/o > Increase fluid intake to target u/o > 2L per day2L per day At 5 yrs, incidence of new stone At 5 yrs, incidence of new stone

formation 12% v 27% formation 12% v 27% increases urine flow rate and lower increases urine flow rate and lower

urine solute concentrationurine solute concentration Avoid high animal protein dietAvoid high animal protein diet Avoid high salt dietAvoid high salt diet

Specific Tx – Calcium Specific Tx – Calcium StonesStones

If hyperoxaluria present, low oxalate diet If hyperoxaluria present, low oxalate diet should be tried firstshould be tried first primary foods to avoid are spinach and nutsprimary foods to avoid are spinach and nuts increasing dietary calcium or adding calcium increasing dietary calcium or adding calcium

supplement with meals should be considered supplement with meals should be considered in addition to a low oxalate diet if insufficient. in addition to a low oxalate diet if insufficient.

Thiazide diuretic for refractory Thiazide diuretic for refractory hypercalciuriahypercalciuria

Potassium citrate for refractory Potassium citrate for refractory hypocitraturiahypocitraturia

Specific Tx – Uric Acid Specific Tx – Uric Acid StonesStones

If hyperuricosuria present, lifestyle If hyperuricosuria present, lifestyle modification with the aim of modification with the aim of reducing uric acid productionreducing uric acid production decreased purine intakedecreased purine intake weight loss should be implemented weight loss should be implemented

Allopurinol for refractory Allopurinol for refractory hyperuricosuriahyperuricosuria

Potassium citrate to alkalinize urinePotassium citrate to alkalinize urine

Specific Treatment – Specific Treatment – Cystine StonesCystine Stones

urinary alkalinizationurinary alkalinization drugs such as tiopronindrugs such as tiopronin

Specific Tx – Struvite Specific Tx – Struvite StonesStones

typically require complete stone typically require complete stone removal with percutaneous removal with percutaneous nephrolithotomy & aggressive nephrolithotomy & aggressive prevention and tx of future UTI’sprevention and tx of future UTI’s

MonitoringMonitoring

Monitoring w/ US or plain film for Monitoring w/ US or plain film for new stone formation new stone formation initially at one yearinitially at one year if –ve then every 2-4 yrs based on risk if –ve then every 2-4 yrs based on risk

recurrencerecurrence not nearly as sensitive for identifying not nearly as sensitive for identifying

stones as CT, but CT exposes pt to stones as CT, but CT exposes pt to significant amt of radiation significant amt of radiation

Asymptomatic StoneAsymptomatic Stone

Balance risk of stone becoming asymptomatic Balance risk of stone becoming asymptomatic vs. morbidity assoc with therapyvs. morbidity assoc with therapy

Specific factors will dictate how to manageSpecific factors will dictate how to manage stone size and locationstone size and location

Active surveillance reasonable approach in Active surveillance reasonable approach in asymptomatic pts with asymptomatic pts with small, non-infected calculismall, non-infected calculi no evidence of obstructionno evidence of obstruction not "at risk" for stone episodes (solitary kidney, not "at risk" for stone episodes (solitary kidney,

urinary tract reconstruction, immunosupression, etc)urinary tract reconstruction, immunosupression, etc)

What about overall diet?What about overall diet?

While one can modify diet after one While one can modify diet after one discovers a kidney stone is there any discovers a kidney stone is there any type of diet that prevents kidney type of diet that prevents kidney stones?stones?

Any data available?Any data available?

Dash Diet & Kidney Dash Diet & Kidney StonesStones

Dash-style Diet Associates with Dash-style Diet Associates with Reduced Risk for Kidney StonesReduced Risk for Kidney Stones Eric Taylor, Teresa Fung and Gary Eric Taylor, Teresa Fung and Gary

CurhanCurhan J am Soc Nephrology 20: 2253-2259, J am Soc Nephrology 20: 2253-2259,

20092009 Dietary Approaches to Stop Dietary Approaches to Stop

Hyperstension (DASH)Hyperstension (DASH)


Examined relationship between DASH-style Examined relationship between DASH-style Diet and incident kidney stones in Diet and incident kidney stones in Health Professionals Follow-up study (n-45,821 Health Professionals Follow-up study (n-45,821

men; 18 yr follow up)men; 18 yr follow up) Nurses’ Health Study (n= 101,837 women; 14 year Nurses’ Health Study (n= 101,837 women; 14 year

follow up) follow up) Goal to look at dietary pattern as opposed to Goal to look at dietary pattern as opposed to

individual dietary factorsindividual dietary factors In many cases consuming less of one dietary In many cases consuming less of one dietary

factor to decrease stone risk may lead to factor to decrease stone risk may lead to consumption of other factors that increase riskconsumption of other factors that increase risk


DASH score based on eight componentsDASH score based on eight components High intake ofHigh intake of

FruitsFruits VegetablesVegetables Nuts and legumesNuts and legumes Low-fat dairy productsLow-fat dairy products Whole grainsWhole grains

Low intake ofLow intake of SodiumSodium Sweetened beveragesSweetened beverages Red and processed meatsRed and processed meats


Pts with higher DASH scores had Pts with higher DASH scores had higher intakes of calcium, potassium, higher intakes of calcium, potassium,

magnesium, oxalate and vitamin Cmagnesium, oxalate and vitamin C lower intakes of sodium lower intakes of sodium

Participants in highest compared to lowest Participants in highest compared to lowest quintile of DASH score had an adjusted quintile of DASH score had an adjusted relative risk of 0.55 in men and 0.58-0.60 relative risk of 0.55 in men and 0.58-0.60 in women for kidney stonesin women for kidney stones Robust despite adjustments & substantial Robust despite adjustments & substantial

differences in individual dietary factors and risk differences in individual dietary factors and risk between men and womenbetween men and women


Study ConclusionStudy Conclusion

““consumption of DASH style diet is consumption of DASH style diet is associated with marked decrease in associated with marked decrease in kidney stone risk” (though limited as kidney stone risk” (though limited as cohort study)cohort study)

My conclusion:My conclusion:

I AM IN BIG I AM IN BIG TROUBLE !TROUBLE !

Take Home PointsTake Home Points

Kidney Stones are fairly commonKidney Stones are fairly common CT KUB is best test for diagnosis in CT KUB is best test for diagnosis in

acute settingacute setting Most acute renal colic tx Most acute renal colic tx

conservativelyconservatively Focus on risk factors in work up to Focus on risk factors in work up to

guide investigationsguide investigations Drink lots of fluids and eat healthy Drink lots of fluids and eat healthy

DASH style dietDASH style diet

Documents

Kidney Stones: An Overview Gerald Da Roza MD, MHSc, FRCPC March 15, 2010