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Urinary lithiasis


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Urinary lithiasis

  1. 1. Urinary LithiasisUrinary Lithiasis in childrenin children Prof. Dr. Saad S Al Ani Senior Pediatric Consultant Head of Pediatric Department Khorfakkan Hospital Sharjah ,UAE
  2. 2. Urinary LithiasisUrinary Lithiasis • The wide geographic variation in the incidence of lithiasis in childhood is related to: – Climatic – Dietary – Socioeconomic factors • Approximately 7% of urinary calculi occur in children <16 yr of age. 22
  3. 3. Stone formationStone formation • Approximately 75% of all stones contain calcium as a major constituent, and 60% are composed of calcium oxalate • Most “spontaneous” stones are composed of calcium, oxalate, or phosphate crystals(COP) – Others are due to uric acid, cystine, ammonium crystals, or phosphate crystals, or a combination of these substances (UCAP) 33
  4. 4. Stone formationStone formation (Cont.)(Cont.) • The risk of stone formation increases in the presence of increasing concentrations of these crystals and is reduced with increasing concentrations of inhibitors. 44
  5. 5. Stone formationStone formation (Cont.)(Cont.) • Renal calculi develop from crystals that form on the calyx and aggregate to form a calculus • Bladder calculi may be stones that formed in the kidney and traveled down the ureter, or they can form primarily in the bladder. 55
  6. 6. Stone formationStone formation (Cont.)(Cont.) • Stone formation depends on four factors: 1. Matrix 2. Precipitation-crystallization 3. Epitaxy 4. Absence of inhibitors of stone formation in the urine 6
  7. 7. Stone formationStone formation (Cont.)(Cont.) 1. Matrix – Is a mixture of protein , non-amino sugars, glucosamine, water, and organic ash – Makes up 2-9% of the dry weight of urinary stones – Is arranged within the stones in organized concentric laminations 7
  8. 8. Stone formationStone formation (Cont.)(Cont.) 2. Precipitation-crystallization – Refers to supersaturation of the urine with specific ions composing the crystal. – Crystals aggregate by chemical and electrical forces. 8
  9. 9. Stone formationStone formation (Cont.)(Cont.) Precipitation-crystallization (Cont.)(Cont.) – Saturation of urine with respect to the ions increases: • Rate of nucleation, crystal growth, and aggregation • likelihood of stone formation and growth 9
  10. 10. Stone formationStone formation (Cont.)(Cont.) 3. Epitaxy – Refers to the aggregation of crystals of different composition but similar lattice structure, thus forming stones of a heterogeneous nature. – e.g. calcium oxalate and monosodium urate have similar structures and calcium oxalate crystals can aggregate on a nucleus of monosodium urate crystals. 10
  11. 11. Stone formationStone formation (Cont.)(Cont.) 4. Inhibitors of stone formation Urine contains inhibitors of stone formation, including: i. Citrate ii. Diphosphonate iii. Magnesium ion 11
  12. 12. Clinical ManifestationsClinical Manifestations • Gross or microscopic hematuria • Severe abdominal or flank pain (renal colic) ( If the calculus is in the renal pelvis, calyx , or ureter and causes obstruction) – Typically the pain radiates anteriorly to the scrotum or labia. – Often the pain is intermittent 12
  13. 13. Clinical ManifestationsClinical Manifestations (Cont.)(Cont.) • Irritative symptoms of dysuria, urgency, and frequency (If the calculus is in the distal ureter) • Asymptomatic. (If the stone passes into the bladder) 13
  14. 14. Clinical ManifestationsClinical Manifestations (Cont.)(Cont.) • Dysuria and difficulty voiding can result, particularly in boys. (If the stone is in the urethra) • Pass small amounts of gravel-like material. (Some children ) 14
  15. 15. DiagnosisDiagnosis • Approximately 90% of urinary calculi are calcified to some degree and consequently are radiopaque on a plain abdominal film – Struvite (magnesium ammonium phosphate) stones are radiopaque. – Cystine, xanthine, and uric acid calculi may be radiolucent 15
  16. 16. DiagnosisDiagnosis (Cont.)(Cont.) • Some children have nephrocalcinosis, (which is calcification of the renal tissue itself ) • Unenhanced spiral CT scan of the abdomen and pelvis is the most accurate study ( if a child with suspected renal colic) – 96% sensitivity and specificity in: Delineating the number and location of calculi Demonstrates whether the involved kidney is hydronephrotic 16
  17. 17. DiagnosisDiagnosis (Cont.)(Cont.) • An alternative is to obtain a plain radiograph of the abdomen and pelvis plus a renal ultrasonogram. • Any material that resembles a calculus should be sent for analysis by a laboratory that specializes in identifying the components of urinary calculi 17
  18. 18. Metabolic EvaluationMetabolic Evaluation • A metabolic evaluation for the most common predisposing factors should be undertaken in all children with urolithiasis bearing in mind that structural, infectious, and metabolic factors often coexist. 18
  19. 19. Metabolic EvaluationMetabolic Evaluation (Cont.)(Cont.) • Laboratory tests suggested for evaluation of urolithiasis 19 I. Serum • Calcium • Electrolytes and anion gap • Phosphorus • Creatinine • Uric acid • Alkaline phosphatase
  20. 20. Metabolic EvaluationMetabolic Evaluation(Cont.)(Cont.) 20 II . Urine • Urinalysis • 24-hr collection for: - Creatinine clearance - Oxalate - Calcium - Uric acid - Phosphate - Dibasic amino acids • Urine culture • Calcium / creatinine ratio • Spot test for cystinuria
  21. 21. Metabolic EvaluationMetabolic Evaluation(Cont.)(Cont.) • In children with hypercalciuria, further studies of : - Calcium excretion - Dietary calcium restriction - Calcium loading are necessary 21
  22. 22. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi 1.Calcium1.Calcium Oxalate and Calcium PhosphateOxalate and Calcium Phosphate CalculiCalculi •The most common metabolic abnormality in these patients is normocalcemic hypercalciuria •Between 30% and 60% of children with calcium stones have hypercalciuria without hypercalcemia. 22
  23. 23. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) • Hypercalciuria may be absorptive, renal, or resorptive 23 Type Serum Ca++ Restricted Ca++ (urine) Fasting Ca++ (urine) Ca++ load (urine) S.PTH Absorptive N N or ↑ N ↑ ↑ Renal N ↑ ↑ ↑ N Resorptive ↑ ↑ ↑ ↑ ↑ S.PTH :serum parathyroid hormone
  24. 24. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Other metabolic aberrations that predispose to stone disease include : 24 1.Hyperoxaluria 2.Heterozygous cystinuria 3.Hyperuricosuria 4.Hypomagnesuria 5.Hypocitruria 6.Hyperparathyroidism 7.Renal tubular acidosis
  25. 25. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) 2.Cystine Calculi2.Cystine Calculi •Cystinuria accounts for 1% of renal calculi in children •Rare autosomal recessive disorder •Disorder of the epithelial cells of the renal tubule that prevents absorption of the 4 dibasic amino acids (Cystine, Ornithine , Lysine, Arginine,) (COLA) and results in excessive urinary excretion of these products. 25
  26. 26. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) 3.Struvite Calculi3.Struvite Calculi •Magnesium ammonium phosphate •In the kidney, the calculi often have a staghorn configuration, filling the calyces •The calculi act as foreign bodies, causing: - Obstruction - Perpetuating infection - Causing gradual kidney damage 26
  27. 27. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Struvite Calculi (cont.)Struvite Calculi (cont.) •Patients with struvite stones also can have metabolic abnormalities that predispose to stone formation. •These stones often are seen in children with neuropathic bladder dysfunction, particularly those who have undergone an ileal conduit procedure 27
  28. 28. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Urea-splitting organisms (most often Proteus spp, and occasionally Klebsiella spp , Escherichia coli, Pseudomonas spp, and others) 28 Urinary tract infections Urinary alkalinization and excessive production of ammonia Precipitation of magnesium ammonium phosphate (struvite) and calcium phosphate Struvite CalculiStruvite Calculi (cont.)(cont.)
  29. 29. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) 4. Uric Acid Calculi4. Uric Acid Calculi •Calculi containing uric acid are more common in less-developed areas of the world. •Hyperuricosuria with or without hyperuricemia is the common underlying factor in most cases •The stones are radiolucent 29
  30. 30. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Uric Acid Calculi (cont.)Uric Acid Calculi (cont.) • DiagnosisDiagnosis should be suspected in a patient with persistently acid urine and urate crystalluria • Hyperuricosuria can result from various inborn errors of purine metabolism 30
  31. 31. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Uric Acid Calculi (cont.)Uric Acid Calculi (cont.) Causes of urate calculi:Causes of urate calculi: •Lesch-Nyhan syndrome •Glucose- 6-phosphatase deficiency •Short-bowel syndrome( e.g. ileostomies) •Chronic dehydration and acidosis •Some tumors and myeloproliferative diseases 31
  32. 32. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) 5.Indinavir Calculi5.Indinavir Calculi •Indinavir sulfate is a protease inhibitor approved for treating HIV infection. •Up to 4% of patients acquire symptomatic nephrolithiasis. •Most of the calculi are radiolucent and are composed of indinavir-based monohydrate, although calcium oxalate and/or phosphate have been present in some. 32
  33. 33. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Indinavir Calculi (cont.)Indinavir Calculi (cont.) • After each dose, 12% of the drug is excreted unchanged in the urine. •The urine in these patients often contains crystals of characteristic rectangles and fan-shaped or starburst crystals. 33
  34. 34. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) Indinavir Calculi (cont.)Indinavir Calculi (cont.) •Indinavir is soluble at a pH of <5.5. •Dissolution therapy by urinary acidification with : - Ammonium chloride or - Ascorbic acid 34
  35. 35. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) 6.Nephrocalcinosis6.Nephrocalcinosis • Nephrocalcinosis refers to calcium deposition within the renal tissue. • Often nephrocalcinosis is associated with urolithiasis. 35
  36. 36. Pathogenesis of specificPathogenesis of specific Renal CalculiRenal Calculi (Cont.)(Cont.) 6.Nephrocalcinosis (Cont.)6.Nephrocalcinosis (Cont.) •The most common causes are: 36 • Furosemide • Cortical necrosis • Distal RTA • Hyperoxaluria • Hyperparathyroidism • Prolonged immobilization • Medullary sponge kidney • Cushing syndrome • Hypophosphatemic rickets • Hyperuricosuria • Sarcoidosis • Renal candidiasis
  37. 37. Treatment • In a child with a renal or ureteral calculus, the decision whether to remove the stone depends on: - Location - Size - Composition (if known) - Obstruction and/or infection if is present. 37
  38. 38. Treatment (cont.) • If the calculus does not pass or seems unlikely to pass or if there is associated urinary tract infection, removal is necessary • Lithotripsy of bladder, ureteral, and small renal pelvic calculi using the holmium laser through a flexible or rigid ureteroscope is quite effective 38
  39. 39. Treatment (cont.) • In children with hypercalciuriaIn children with hypercalciuria: - Some reduction in calcium and sodium intake is necessary -Thiazide diuretics also reduce renal calcium excretion. -Addition of potassium citrate, an inhibitor of calcium stones, with a dosage of 1-2 mEq/kg/24hr is beneficial. 39
  40. 40. Treatment (cont.) • In patients with uric acid stones:In patients with uric acid stones: - allopurinol is effective • In patients with cystine stones:In patients with cystine stones: - Alkalinization of urine with sodium bicarbonate or sodium citrate is effective. • D- penicillamine, which is a chelating agent that binds to cysteine or homocysteine, increasing the solubility of the product 40
  41. 41. Treatment (cont.) • Treatment of type 1 RTATreatment of type 1 RTA -- Involves: *Correcting the metabolic acidosis *Replacing lost potassium and sodium • Treatment of primary hyperoxaluriaTreatment of primary hyperoxaluria -- Involves: * Liver transplantation * Kidney transplantation 41
  42. 42. References • Lottmann H, Gagnadoux MF, Daudan M: Urolithiasis in children. In Gearhart JP, Rink RC, Mouriquand PDE, editors: Pediatric urology, ed 2, Philadelphia,2010, Saunders, pp 631–661 • • • • Nacaroglu HT, Demircin G, Bülbül M, Erdogan O, Akyüz SG, Caltik A. The association between urinary tract infection and idiopathic hypercalciuria in children. Ren Fail. 2013;35(3):327-32. • • • 42
  43. 43. Thank youThank you Prof. Dr. Saad S Al Ani Khorfakkan Hospital ,Sharjah ,UAE