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Nephrolithiasis
Karen Estrella-Ramadan
07/06/12
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The classic adult presentation of sudden,
debilitating flank pain is uncommon in
children.

50%: abdominal, flank, or pelvic pain (>in older
children and adolescents)
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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
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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
Etiology
1. CALCIUM
• Most children who have
hypercalciuria and
urolithiasis have normal
serum calcium
concentrations.
2. Infection

> associated with
Proteus,
Providencia,
Klebsiella,
Pseudomonas,
Enterococci
◦ Urease producers
◦ Highly favorable for
struvite (magnesium
ammonium
phosphate) stone
formation
3. Uric acid
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
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Few 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 Oxalosis
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Primary hyperoxalurias types I and II: rare autosomal
recessive
◦ includes nephrocalcinosis and nephrolithiasis
◦ Growth failure, malnutrition, uremia
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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. Cystinuria

Autosomal recessive disorder of renal
tubular transport
◦ excessive excretion of cystine, arginine, lysine,
and ornithine.
Other Causes
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CF: sec to hypercalciuria, hyperoxaluria, and
hypocitraturia
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Drugs: TMP-SMX and ceftazidime , protease
inhibitors (indinavir), furosemide,
acetazolamide, and allopurinol
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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.
CBC, CMP, uric acid
Gillespie R S , Stapleton F B Pediatrics in Review
2004;25:131-139
©2004 by American Academy of Pediatrics
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
Labs

Complete
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
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Further workup if no stone or + calcium
oxalate:
◦ Cystine levels (urine) in 1st specimen
◦ PTH: if hypercalciuria, hypercalcemia, hypoP
◦ Vitamin D levels
Treatment
Goals:
 Prevent additional renal damage
 Manage pain
 Expedite passage or removal of any
stones
 Prevent new stones from forming.
Conservative
Increase water intake
 Analgesics:
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◦ 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 cx
 Peds Urology referral
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Stone Removal
• <5mm stones will pass without further tx
 Intervene 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)
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< 1cm on pelvis
2. Percutaneous nephrostolithotomy (PCNL)
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> 2 cm, harder stones: calcium, cystine, structural anormalities
3. Ureteroscopy
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In Ureter or bigger (struvite)
Treatment specific
1. 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. Hyperoxaluria
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Decrease Na intake
Avoid:
◦ As vitamic C and D
? Supplemental: citrate, Mg, P
Increase calcium intake
Diuretics: hydrochlorothiazide
Combined liver and kidney transplantation
remains the only definitive therapy.
3. Uric Acid
 Decrease 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)
References
http://pedsinreview.aappublications.org/c
ontent/25/4/131.full.pdf+html
 http://pednephrology.stanford.edu/secure
/documents/Nephrolithiasis-Children.pdf
 http://emedicine.medscape.com/article/9
83884-treatment#a1156
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