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