1. Karen Estrella-Ramadan 07/06/12
Nephrolithiasis
Karen Estrella-Ramadan
07/06/12

2. In infants may mimic colic, > vomiting
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

3. Balance of stone-promoting and -inhibiting factors.
Gillespie R S , Stapleton F B Pediatrics in Review 2004;25:
©2004 by American Academy of Pediatrics

4. 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.

5. 2. Infection
> associated with Proteus, Providencia, Klebsiella, Pseudomonas, Enterococci
Urease producers
Highly favorable for struvite (magnesium ammonium phosphate) stone formation

6. 3. Uric acid 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.

7. 3.Hyperoxaluria and Oxalosis
Primary 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.

8. 4. Cystinuria Autosomal recessive disorder of renal tubular transport
excessive excretion of cystine, arginine, lysine, and ornithine.

9. Other 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.

10. CBC, CMP, uric acid
Suggested algorithm for evaluating possible nephrolithiasis.
Gillespie R S , Stapleton F B Pediatrics in Review 2004;25:
©2004 by American Academy of Pediatrics

11. Hypoechoic shadow

12. Renal calculus on unenhanced computed tomography (CT).
Renal calculus on unenhanced computed tomography (CT). With judicious use, noncontrast helical CT may be helpful in identifying renal calculi (such as the one circled) as well as nonrenal causes of abdominal symptoms.
Gillespie R S , Stapleton F B Pediatrics in Review 2004;25:
©2004 by American Academy of Pediatrics

14. 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

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

16. Treatment Goals: Prevent additional renal damage Manage pain
Expedite passage or removal of any stones
Prevent new stones from forming.

17. Conservative Increase water intake Analgesics: Abx: if + urine cx
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

18. 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:
Extracorporeal shock wave lithotripsy (ESWL)
< 1cm on pelvis
Percutaneous nephrostolithotomy (PCNL)
> 2 cm, harder stones: calcium, cystine, structural anormalities
Ureteroscopy
In Ureter or bigger (struvite)

19. 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

20. 2. Hyperoxaluria 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.

21. 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

22. 4. Cystine:
Hydration + urine alkalinization
Refractory: D-penicillamine, tiopronin, and alpha-mercaptopropionylglycine (bind cystine)

23. References
ontent/25/4/131.full.pdf+html
/documents/Nephrolithiasis-Children.pdf
treatment#a1156