NephrolithiasisNephrolithiasisKaren Estrella-Ramadan

07/06/12

The classic adult presentation of sudden, debilitating flank pain is uncommon in children.

50%: abdominal, flank, or pelvic pain (>in older children and adolescents)

In infants may mimic colic, > vomiting

In preschool-age children: as UTI

33%-90%: Gross or microscopic hematuria is found in 33% to 90% (equally across age groups)◦ 3 samples (1 wk apart) with RBC > 5

Balance of stone-promoting and -inhibiting factors.

Gillespie R S , Stapleton F B Pediatrics in Review 2004;25:131-139

©2004 by American Academy of Pediatrics

EtiologyEtiology

Increased Intestinal Calcium Absorption◦ Vitamin D excess

Renal Tubular Dysfunction◦ Renal tubular phosphate leak◦ Impaired renal tubular calcium

absorption◦ Type 1 (distal) renal tubular acidosis◦ Dent disease◦ Bartter syndrome

Endocrine Disturbances ◦ Hypothyroidism◦ Adrenocorticoid excess◦ Hyperparathyroidism

Bone Metabolism Disorders◦ Immobilization◦ Rickets◦ Malignancies◦ Juvenile rheumatoid arthritis

Other ◦ Familial idiopathic hypercalciuria◦ Drugs (certain diuretics, corticosteroids)◦ Urinary tract infection◦ Williams syndrome◦ Increased renal prostaglandin E2

production ◦ Hypercalcemia◦ Hypophosphatemia◦ Glycogen storage disease

1. CALCIUM • Most children who have

hypercalciuria and urolithiasis have normal serum calcium concentrations.

2. Infection2. Infection> associated with

Proteus, Providencia, Klebsiella, Pseudomonas, Enterococci◦Urease producers◦Highly favorable for

struvite (magnesium ammonium phosphate) stone formation

3. Uric acid3. Uric acidFew childhood stones are

composed purely of uric acid. Uric acid excretion is highest in

infancy and remains high, relative to adult values, until adolescence.

Normal levels of urinary uric acid are so high in infants that crystals may precipitate in diapers and be misidentified as blood.

3.Hyperoxaluria and Oxalosis3.Hyperoxaluria and OxalosisPrimary hyperoxalurias types I and II: rare autosomal

recessive◦ includes nephrocalcinosis and nephrolithiasis◦ Growth failure, malnutrition, uremia

Secondary hyperoxaluria: sec to excessive intake of oxalate precursors (ethylene glycol, ascorbic acid), increased absorption of oxalate (IBD, extensive bowel resection), or deficiency of cofactors in oxalate metabolism (pyridoxine deficiency)

◦ Oxalosis develops as calcium oxalate precipitates in multiple organs and joints.

◦ Oxalate deposition in the kidneys impairs renal function, further elevating serum oxalate levels.

4. Cystinuria4. Cystinuria

Autosomal recessive disorder of renal tubular transport◦excessive excretion of cystine, arginine, lysine,

and ornithine.

Other CausesOther Causes

CF: sec to hypercalciuria, hyperoxaluria, and hypocitraturia

Drugs: TMP-SMX and ceftazidime , protease inhibitors (indinavir), furosemide, acetazolamide, and allopurinol

An important emerging cause of childhood

stones is the ketogenic diet, with an incidence of urologic stones as high as 10%. Used for refractory seizures◦A high-protein, low-carbohydrate, low-fluid dietary

regimen is associated with hypercalciuria, hyperuricosuria, hypocitraturia, and low urine volume.

Gillespie R S , Stapleton F B Pediatrics in Review 2004;25:131-139

©2004 by American Academy of Pediatrics

CBC, CMP, uric acid

Hypoechoic shadow

Renal calculus on unenhanced computed tomography (CT).

Gillespie R S , Stapleton F B Pediatrics in Review 2004;25:131-139

©2004 by American Academy of Pediatrics

LabsLabsComplete

metabolic evaluation: ◦ Pt at home, consuming

regular diet and with no infection.

◦ ideally get 24hrs urine collection, but due that is difficult, new standards for single collections

Further workup if no stone or + calcium oxalate: ◦Cystine levels (urine) in 1st specimen◦PTH: if hypercalciuria, hypercalcemia, hypoP◦Vitamin D levels

TreatmentTreatment

Goals:Prevent additional renal damageManage painExpedite passage or removal of any

stonesPrevent new stones from forming.

ConservativeConservative

Increase water intakeAnalgesics:

◦Mild: NSAIDS (stop 3 days before sx procedure)◦Moderate: Tylenol + codeine◦Severe: Morphine*in cases of distal: may use doxazosin (alpha blocker)

Abx: if + urine cxPeds Urology referral

Stone RemovalStone Removal• <5mm stones will pass without further txIntervene if: signs of infection, complete

obstruction, partial obstruction by a stone in a solitary kidney, renal insufficiency, or if the stone is greater than 5 mm in diameter, as it is unlikely to pass spontaneously.

Options:1. Extracorporeal shock wave lithotripsy (ESWL)

< 1cm on pelvis

2. Percutaneous nephrostolithotomy (PCNL) > 2 cm, harder stones: calcium, cystine, structural anormalities

3. Ureteroscopy In Ureter or bigger (struvite)

Treatment specificTreatment specific1. Hypercalciuria:

◦Good hydration + a low-sodium diet ◦If doesn’t work: Thiazide diuretics (stimulating

calcium reabsorption in the distal tubule)◦Patients should avoid vitamin D supplements.◦Citrate supplementation helps prevent stones

in patients who have renal tubular acidosis or hypocitraturia.

◦Avoid high protein diet (increase calcium excretion)

◦High K diet

2. HyperoxaluriaDecrease Na intakeAvoid:

◦As vitamic C and D? Supplemental: citrate, Mg, PIncrease calcium intakeDiuretics: hydrochlorothiazide Combined liver and kidney transplantation

remains the only definitive therapy.

3. Uric AcidDecrease Na intake- may decrease urinary

uric acid (and calcium) excretion. If fails: base supplementation with citrate

or bicarbonate may be indicated. ◦Alkaline urine= > solubility of uric acid ◦Allopurinol

4. Cystine:Hydration + urine alkalinization Refractory: D-penicillamine, tiopronin, and

alpha-mercaptopropionylglycine (bind cystine)

ReferencesReferenceshttp://pedsinreview.aappublications.org/

content/25/4/131.full.pdf+htmlhttp://pednephrology.stanford.edu/

secure/documents/Nephrolithiasis-Children.pdf

http://emedicine.medscape.com/article/983884-treatment#a1156