RENAL STONE IN CHILDREN Ali Derakhshan MD Shiraz university of Medical Sciences Shiraz-Iran بهمن 9626

Case1 8 mo old baby presented with irritability, an US →19 mm stone in LP of LT kidney,since his older brother was a case of cystine stone , urine sample →+nitroprusside test for cystine Urologic consult →can wait on medical Rx since non-obstructive Combination Rx with polycitra-K+ captopril+ vit. B6+ D-penicillamine, 6 weeks later stone size  to 12 mm and Rx continued with a 3mo F up At this time US was entirely NL.

CASE 2 3yrs old♀, fever and abdominal pain,active UA,UC to follow, Past Hx:open surgery for a Lt.pelvic stone 1yr ago with composition85% cystine but no follow up Rx. US 8mm stone in lt proximal ureter +hydronephrosis +2other 6mm and 5 mm stone in lt U and Lower pole.

Case 3 45days old♂ with colicky pain,an US revealed a few gravel 1-1.5 mm in each kidney NL UA -----------------------------

Urinary tract obstruction Common cause of acute and chronic renal failure Potentially curable form of kidney disease

Our ESRD children 1990-1999 116 children on hemodialysis Major causes of ESRD in order of frequency were glomerulopathies 23 (19.83%), reflux 15 (12.93%), chronic pyelonephritis without reflux 11 (9.5%), cystic diseases 10 (8.62%), neurogenic bladder 10 (8.62%) stone disease 9 (7.75%), posterior urethral valve 7 (6.03%) ureteropelvic junction obstruction 7 (6.03%)= total obst:29%UTO

Epidemiology Rate of symptomatic stone formation was 7.9/10000 in 1996, increased to 18.5/10000 in 2007. Adult rate : Asia 1-5% Europe 5-9% North America 13% Saudi Arabia 20%

Causes of increase incidence: The causes of increase incidence is unknown but obesity, higher salt intake, lower water intake, low Ca diet and high rate of using antibiotics may be considered.

Predisposig Factors 1. Peak Age (20- 40 yr),Adolescents 10 times more symptomatic stone than< 3 yr 2. Sex (M>F) 3. Race 4. Environmental and Socioeconomic Factors 5. Genetic Factors, Obesity 6. Dietary Habits

Renal stone Composition Ca is found in 90% Ca-oxalate(40-60%) ca-phosphate(15-25%) Ca-oxalate + Ca-phosphate(10-25%) Struvite(17-30%) Uric acid(2-10%) Cystine(6-8%) xanthin, Hypoxanthin, Drugs,……

Stone Composition With increasing age : Ca-oxalate stone increases while P and struvite stones decrease.

Mechanism of stone formation Supersaturation Infection - crystals(formation, growth, aggregation, adherence to epithelial cells), presence of matrix & absence of inhibitors. Foreign body or urinary stasis Urine PH

Why stones form… Acidic urine: Uric acid, Cystine, Ca Oxalate 1. Decreased urine volume… Urine concentrates, supersaturates & crystals precipitate. 2. Urine pH affects solubility… Acidic urine: Uric acid, Cystine, Ca Oxalate Alkaline urine: Ca phosphate, struvite Promotes precipitation of:

Why stones form… 3. Absence of inhibitors Citrate, glycosaminoglycans and Tam Horsfall proteins,Zn and Mg. 4. Infection: Urea-splitting organisms (Proteus, Klebsiella, E.coli,….) generate ammonia and alkalinize urine Proteus Urease Staghorn calculi (struvite)

Underlying Causes(75%) Hypocitraturia(15-63%) Primary Secondary (acidosis, ↑protein intake, severe exercise, ↑Na intake, ↓urine Mg, UTI, chronic diarrhea, thiazides, hypokalemia) Structural abnormalities(32%) Hyperoxaluria, Cystinuria, RTA Hyperuricosuria, Hypercalciuria(the most common 50%),other rare causes

Management of renal stone Paraclinical evalution indicated in all children since: Once stone always stone 24 hrs. urine for Ca, Cr, Uric acid, Mg, Cystine, citrate and oxalate,urine PH - VBG -BUN,Cr,Na,K,Ca,P,UA,Mg,AG - Stone analysis if any -Some may need genetic evaluation for primary hyperoxaluria

Treatment Pain control Alpha adrenergic blockers (Tamsulosin) ,Ca Channel Blockers Hydration Control of UTI Medical, surgical or ESWL Prevention

Medical treatment Non-pharmacological medical therapy in all children Pharmacological therapy in children with multiple stones at presentation or recurrence of stone during one year.

Renal stone Rate of another stone formation >50% in 5yrs How long to continue medical Rx Depends on the cause for cystine it is mentioned lifelong ?? for other causes 3-6 mo after clearance but at least 5 yrs. FUP

Special indications for drug therapy Hypercalciuria (the most common) RTA Cystinuria Hyperuricosuria Hypocitraturia Hyperoxaluria Hypomagnesuria Citrate compounds HCTZ………… Citrate is recommended for all types of stone except for phosphate & infectious stone

Non-pharmacological Non-surgical therapy ↑Water intake Prevention of heavy exercise ↓Na intake ↓Protein intake (↓urine Ca, ↑Urine PH, ↓Urine uric acid, Effect on urine citrate) Ca-intake (regular or even ↑) ↓Lipid intake ↓Intake of oxalate containing drinks or foods.

Recurrence of renal stone Rcurrence occurs frequently It is higher in children with metabolic abnormalities It is about 5-10% each year So, long term FU and periodic reassessment is indicated Frequency of imaging depends on type, number of stones, severity of metabolic abnormalities, UTI and symptoms.

Sarv Abarkooh Gonbade Ali Abarkooh 24

Results of study in Shiraz 153 children <18 Yr (M/F=1.1) <2 Yr: 37%, 2-6 Yr: 36.6%, >7 Yr: 26% F HX: about 50% positive Stone size <5 mm: 70%, >10 mm: 2.5%. Stone No: 40.5% =1 stone, 42.5%= 2-3 & 17%>3 stones. Bilateral in 37%

24 Hr. Urinary Findings 90.8% had at least one metabolic abnormality Hypomagnesuria 60.8% Hypocitraturia 52.9% Hypercalciuria 47.1% Hyperuricosuria 37.3% Hyperoxaluria 17% Cystinuria 2%