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Nephrolithiasis

Epidemiology

  • 1-2% incidence
  • Male and female equally affected
  • 30-50 years
  • Increased incidence in developed countries – high animal fat diet
  • Tends to recur, hypocitrauria is a major risk factor and causes saturation

Classification – F. Heller 1860

NB – Most stones are calcium oxalate and have idiopathic etiology

  • Oxalate
  • Carbonate
  • Mixed
  • Uric acid
  • Phosphates
  • Cysteine

Pathogenesis

  • Stable saturated solution undergoes some change to make it unstable and results in crystallisation – first step
  • Supersaturation is dependent on free ion state not concentration
  • Formal genesis
    • Nucleation
    • Increased concentration of calculi causing substance in the urine
      • Hyperuricuria >200mg, hypercalciuria >300mg, hyperoxaluria >40mg, cysteinuria >10mg
    • Insufficient secretion of compounds that inhibition crystallisation
      • pyrophosphate, magnesium, MPS
    • change of urine pH
      • <5.8 – favours uric acid + oxalate stones
      • >7 – favours phosphate + cysteine stones
    • Low urine volume
  • Causal genesis – general predisposing factors
    • Geography + climate
    • Nutrition, home life, profession
    • Genetic and morbid – gout, hyperPTH, vit D intoxication
    • Disturbed urine flow – malformation, UT hypotonia, prostatic adenoma
    • UTI – change in pH, ammonia secretion

Clinical features

  • None
  • Small calculi
    • classic triad
      • Renal colic – lumbar/abd pain due to acute obstruction + increased intracavital urine P
      • Nausea + vomiting
      • Hematuria
    • Complaint, physical data, lab findings
  • Big calculi
    • Dull pain, HU, UTI (non specific)
  • Complications
    • Hydronephrosis
    • Obstructive nephropathies
    • Pyelonephritis, sepsis
    • CRF

Diagnosis

  • History
  • Physical exam
  • Lab exam
    • Urine – HU, Crystaluria
    • Blood – Ca, P, cAMP, PTN, BUN
  • Imaging – US, XR , CT
  • Chemical analysis of calculi
  • Assess complications
  • Assess renal function

Treatment – complex, continuing, precise

  • Tx for renal colic
    • Parenteral – ONLY
    • Combine – analgesic, cholinolytic, sedative
      • Analgesic
        • Metamizole (Analgin) – 1g/2ml amp. 1g
        • Paracetamol, ibuprofen, indometacin
      • Cholinolytic
        • Atropine – [0.1%/ml amp. 1mg] (max dose – 1mg per inj; 3mg in 24hrs)
      • Sedative – sodium/calcium bromide
  • Tx between colic – spontaneous elimination
    • Increase urine volume – 3-4L of water intake per day (water blow)
    • Oral cholinolytics and NSAIDs
  • Prophylactic and conservative tx – regimen and diet
  • Specific for UA stones – alkalinisation, allopurinol
  • Thiazides – decrease calcium excretion if hypokalemia develops give amiloride
  • Papaverine [20mg]
  • Diazepam
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