KIDKIDNEYNEY STOSTONESNES

nephrolithiasis (kidney calculi or stones) is well-nephrolithiasis (kidney calculi or stones) is well-documented common occurrences in the documented common occurrences in the general population general population

The etiology of this disorder is multifactorial and The etiology of this disorder is multifactorial and is strongly related to dietary lifestyle habits or is strongly related to dietary lifestyle habits or practices. practices.

Urinary calculi or stones are the most common Urinary calculi or stones are the most common cause of acute ureteral obstruction. cause of acute ureteral obstruction.

The term nephrolithiasis (kidney calculi or The term nephrolithiasis (kidney calculi or stones) refers to the entire clinical picture of the stones) refers to the entire clinical picture of the formation and passage of crystal agglomerates formation and passage of crystal agglomerates called calculi or stones in the urinary tract called calculi or stones in the urinary tract

Activity means:Activity means: Formation of new stonesFormation of new stones Enlargement of old stones Enlargement of old stones Passage of gravel Passage of gravel Despite attempted dietary modification Despite attempted dietary modification

over a 3 to 6 month period. over a 3 to 6 month period.

Nephrocalcinosis: Nephrocalcinosis: calcification of renal calcification of renal papilla that if break loose cause colicpapilla that if break loose cause colic

Sludge: Sludge: sufficient uric acid or cystine in sufficient uric acid or cystine in the urine may plug both ureters with the urine may plug both ureters with precipitateprecipitate

Staghorn calculi: Staghorn calculi: struvite, cystine, and struvite, cystine, and uric aciduric acid

EpidemiologyEpidemiology3:1 M:F (~7% men/ 3% women) Women typically excrete 3:1 M:F (~7% men/ 3% women) Women typically excrete more citrate and less calcium than men more citrate and less calcium than men Ethnic Background Ethnic Background Stones are rare in Native Stones are rare in Native Americans, Africans, American Blacks, and IsraelisAmericans, Africans, American Blacks, and Israelis33rdrd-5-5thth decade most common (70%) decade most common (70%) predispositicve diseases:predispositicve diseases: (RTA type 1, Hyper- (RTA type 1, Hyper-parathyroidism, cysteinuria, milk-alkali syndrome, parathyroidism, cysteinuria, milk-alkali syndrome, sarcoidosis, Crohn's disease) sarcoidosis, Crohn's disease) Family HistoryFamily History produce excess amounts of a produce excess amounts of a mucoprotein in the kidney or bladder allowing crystallites mucoprotein in the kidney or bladder allowing crystallites to be deposited and trapped forming calculi or stonesto be deposited and trapped forming calculi or stonesClimateClimate (mountainous, desert, or tropical) (mountainous, desert, or tropical)Time of yearTime of year (warmest three months) (warmest three months) LifestyleLifestyle (sedentary) (sedentary)MedicationsMedications: protease inhibitors, carbonic anhydrase : protease inhibitors, carbonic anhydrase inhibitorsinhibitors

10% of all people will have a kidney stone in 10% of all people will have a kidney stone in their lifetimetheir lifetime

1 in 1,000 adults are hospitalized annually in 1 in 1,000 adults are hospitalized annually in the United States for renal calculithe United States for renal calculi

50% of those who develop a renal stone will 50% of those who develop a renal stone will have a recurrence within the next 5-7 yearshave a recurrence within the next 5-7 years

Urinary calculi found in 1% of all autopsiesUrinary calculi found in 1% of all autopsies

Types of Renal CalculiTypes of Renal Calculi

Calcium StonesCalcium Stones Calcium Oxalate (60%)Calcium Oxalate (60%)

Calcium Phosphate (10%)Calcium Phosphate (10%)

Calcium Oxalate and Calcium Calcium Oxalate and Calcium Phosphate (10%)Phosphate (10%)

Struvite Stones (10-15%)Struvite Stones (10-15%)

Uric Acid Stones (5-10%)Uric Acid Stones (5-10%)

Cystine Stones (1-2%)Cystine Stones (1-2%)

Any factor that reduces urinary flow or causes Any factor that reduces urinary flow or causes obstruction, which results in urinary stasis or obstruction, which results in urinary stasis or reduces urine volume through dehydration and reduces urine volume through dehydration and inadequate fluid intake, increases the risk of inadequate fluid intake, increases the risk of developing kidney stones.developing kidney stones.

Low urinary flow is the most common Low urinary flow is the most common abnormality, and most important factor to correct abnormality, and most important factor to correct with kidney stones. It is important for health with kidney stones. It is important for health practitioners to concentrate on interventions for practitioners to concentrate on interventions for correcting low urinary volume in an effort to correcting low urinary volume in an effort to prevent recurrent stone disease prevent recurrent stone disease

PathophysiologyPathophysiology

FormationFormation requires four key elements requires four key elements1.1.Supersaturation of urine with solutesSupersaturation of urine with solutes

2.2.Relative lack of the inhibitors citrate & Relative lack of the inhibitors citrate & pyrophosphatepyrophosphate

3.3.NucleationNucleation

4.4.Stasis or lack of urine flowStasis or lack of urine flow

Clinical PresentationClinical Presentation

Symptoms may vary and depend on the location and Symptoms may vary and depend on the location and size of the kidney stones or calculi within the urinary size of the kidney stones or calculi within the urinary collecting system. In general, symptoms may include collecting system. In general, symptoms may include acute renal or ureteral colic, hematuria (microscopic or acute renal or ureteral colic, hematuria (microscopic or gross blood in the urine), urinary tract infection, or vague gross blood in the urine), urinary tract infection, or vague abdominal or flank pain. A thorough history and physical abdominal or flank pain. A thorough history and physical examination, along with selected laboratory and examination, along with selected laboratory and radiologic studies, are essential to making the correct radiologic studies, are essential to making the correct diagnosis. Small nonobstructing stones or "silent stones" diagnosis. Small nonobstructing stones or "silent stones" located in the calyces of the kidney are sometimes found located in the calyces of the kidney are sometimes found incidentally on x-rays or may be present with incidentally on x-rays or may be present with asymptomatic hematuria. Such stones often pass asymptomatic hematuria. Such stones often pass without causing pain or discomfortwithout causing pain or discomfort

Area of impactionArea of impaction

UPJ UPJ

where ureter passes over pelvic brim and where ureter passes over pelvic brim and iliac vesselsiliac vessels

UVJ: smallest diameter of the urinary tractUVJ: smallest diameter of the urinary tract

In FM the posterior pelvis: ureter is In FM the posterior pelvis: ureter is crossed anteriorly by the pelvic blood crossed anteriorly by the pelvic blood vessels and broad ligamentvessels and broad ligament

Consequences of urinary tract obstruction

Reduced glomerular filtration rate

Reduced renal blood flow (after initial rise)

Impaired renal concentrating ability

Impaired distal tubular function Nephrogenic diabetes insipidus Renal salt wasting Renal tubular acidosis Impaired potassium concentration

Postobstructive diuresis

Intraluminal Intraluminal

pressurepressureRBFRBFGFRGFR

Phase APhase A——... due to... due to

obstructionobstruction

PeristalsisPeristalsis

——... due to... due to

VasodilationVasodilation-ProstacyclinProstacyclin-Prostraglandin Prostraglandin EE22

˜̃...... due todue to

Intratubular Intratubular pressurepressure

Phase BPhase B˜̃...... due todue to

Disorganised Disorganised peristalsis dilation peristalsis dilation of tubules and of tubules and ureterureter

˜̃...... due todue to

VasoconstrictionVasoconstriction-Angiotensin IIAngiotensin II-Thromboxane Thromboxane AA22

˜̃...... due todue to

-Continuing Continuing obstructionobstruction-vasoconstrictiovasoconstrictionn

Acute urinary tract obstruction

Functional consequences

0 6 12 18

Ureteric and tubular pressure

Renal blood flow (RBF)

GFR

Hours

baseline

Calcium StonesCalcium Stones

Hereditary Hereditary HypercalciuriaHypercalciuria condition condition

Main risk factor for calcium stone Main risk factor for calcium stone development in the United Statesdevelopment in the United States

Mean value of calcium in urine in excess Mean value of calcium in urine in excess of:of: 300 mg/day (7.5 mmol/day) for males300 mg/day (7.5 mmol/day) for males 250 mg/day (6.25 mmol/day) for females250 mg/day (6.25 mmol/day) for females

30-40% patients with calcium stones 30-40% patients with calcium stones have hypercalciuriahave hypercalciuria

Struvite StonesStruvite Stones

Triple phosphate or infection stonesTriple phosphate or infection stonesOccur twice as often in women than in Occur twice as often in women than in menmenForm only with presence of bacteria that Form only with presence of bacteria that have urea-splitting enzyme ureasehave urea-splitting enzyme urease

Proteus mirablis, Kelbsiella, Serratia, Proteus mirablis, Kelbsiella, Serratia, Mycoplasma, Psuedomonas, UrealyticumMycoplasma, Psuedomonas, Urealyticum

Alkaline urine promotes struvite calculi Alkaline urine promotes struvite calculi formationformation

Urea-splitting organisms break down ureaUrea-splitting organisms break down urea Carbon dioxide and ammonia are Carbon dioxide and ammonia are

producedproduced Urine pH increasesUrine pH increases Carbonate levels riseCarbonate levels rise

Uric Acid StonesUric Acid Stones

Uric Acid: end product of purine metabolismUric Acid: end product of purine metabolism Derived from exogenous sourcesDerived from exogenous sources Produced endogenously during cell Produced endogenously during cell

turnoverturnover

Contributing disease states to uric-acid Contributing disease states to uric-acid stones:stones: Inflammatory bowel disease, Inflammatory bowel disease,

lymphoproliferative and myeloproliferative lymphoproliferative and myeloproliferative disorders due to increased cellular disorders due to increased cellular breakdown which causes purines to be breakdown which causes purines to be released and so increases uric acid loadreleased and so increases uric acid load

Cystine StonesCystine Stones

Autosomal recessive traitAutosomal recessive trait Inborn dysfunction in reabsorption of dibasic Inborn dysfunction in reabsorption of dibasic

amino acids like cystine, ornithine, lysine, amino acids like cystine, ornithine, lysine, arginine (sometimes seen as COLA) from arginine (sometimes seen as COLA) from renal tubulesrenal tubules

1 in 15,000 people in U.S are affected1 in 15,000 people in U.S are affectedNormal cystine excretion: Normal cystine excretion: << 20 mg/day 20 mg/day> 7.0 urine pH promotes cystine solubility> 7.0 urine pH promotes cystine solubilityMedical Nutrition Therapy: increase fluid intake Medical Nutrition Therapy: increase fluid intake >4 L/day, decrease sodium, may restrict protein >4 L/day, decrease sodium, may restrict protein since methionine is precoursor to cystinesince methionine is precoursor to cystineStandard Medical Practice: with medications, Standard Medical Practice: with medications, keep pH alkaline 24 hrs/daykeep pH alkaline 24 hrs/day

Preventive therapy Preventive therapy It is limited to recurrent stone formers, which It is limited to recurrent stone formers, which

includes patients in whom helical CT on includes patients in whom helical CT on initial symptoms presentation shows initial symptoms presentation shows evidence of more than one stone. evidence of more than one stone.

MONITORINGMONITORING

2424 hour urine collection: 4 to 8 weeks after hour urine collection: 4 to 8 weeks after recommendation, if negative every yearrecommendation, if negative every year..

Ultrasonography at one year if negative Ultrasonography at one year if negative every 2 to 4 years thereafterevery 2 to 4 years thereafter . .

Calcium Oxalate StonesCalcium Oxalate Stones

MANAGEMENTMANAGEMENT

Lifestyle ChangeLifestyle Change

Dietary modificationDietary modification

High fluid intakeHigh fluid intake

Reduced protein intakeReduced protein intake

Limiting sodium intakeLimiting sodium intake

Calcium intakeCalcium intake

Foods and drinks containing oxalateFoods and drinks containing oxalate

beetsbeets chocolatechocolate coffeecoffee colacola nutsnuts rhubarbrhubarb spinachspinach strawberriesstrawberries teatea

wheat branwheat bran

Drug therapy indicated if the stone Drug therapy indicated if the stone disease remains activedisease remains active

Activity meansActivity means::

Formation of new stonesFormation of new stones

Enlargement of old stonesEnlargement of old stones

Passage of gravelPassage of gravel

Despite attempted dietary modification Despite attempted dietary modification over a 3 to 6 month period over a 3 to 6 month period . .

MEDICATIONMEDICATION

Thiazide dureticsThiazide duretics for hypercalciuria for hypercalciuria

AllopurinolAllopurinol or or potassium citrate potassium citrate for hyperuricosuria for hyperuricosuria

potassium citratepotassium citrate for hypocitraturia for hypocitraturia

potassium citratepotassium citrate for type 1 renal tubular acidosis for type 1 renal tubular acidosis