urolithiasis
UROLITHIASIS

Urolithiasis is the formation of urinary stones in the kidney, bladder and/or urethra.

The hallmark of obstruction in the ureter and renal pelvis is the sudden onset of excruciating, intermittent pain that radiates from the flank to the groin or to the genital area and inner thigh.

It is a painful urologic disorder that occurs in 12% of the global population and has a high recurrence rate among male patients.

Lower urinary tract symptoms that are associated with urolithiasis are urgency, frequency, urge incontinence and dysuria.

 

Pharmacotherapy

Alkaline citrate (Sodium & Potassium)

  • A urinary alkalinizer used to prevent uric acid or cystine calculi formation
  • Also used as an adjuvant w/ uricosuric agents in gout therapy
  • Effective in correcting the acidosis of certain renal tubular disorders
  • Contraindicated in patients w/ severe renal impairment w/ oliguria or azotemia, untreated Addison’s disease & severe myocardial damage

Allopurinol

  • Inhibits xanthine oxidase & reduces the production of uric acid w/o disrupting the biosynthesis of vital purines
  • Used in the prevention of gout, renal calculi due to uric acid or calcium oxalate, prophylaxis & treatment of uric acid nephropathy
  • Contraindicated in patients w/ idiopathic hemochromatosis & asymptomatic hyperuricemia

Chlorthalidone

  • A long-acting antihypertensive/diuretic that enhances the excretion of sodium, chloride ions & water by interfering w/ the transport of sodium ions across the renal tubular epithelium
  • Contraindicated in patients w/ known anuria & hypersensitivity to other sulfonamide-derived drugs

Thiazide diuretics (Hydrochlorothiazide)

  • Inhibits the sodium reabsorption in the distal tubules & as a result, the excretion of sodium, water, potassium & hydrogen ions increases
  • Used as treatment for hypercalciuria & calcium stone recurrence
  • Contraindicated in patients w/ known anuria & hypersensitivity to other sulfonamide-derived drugs

Sodium bicarbonate

  • Raises blood & urinary pH by dissociation to provide bicarbonate ions, which neutralizes the hydrogen ion concentration
  • Used to alkalinize the urine & to titrate the dose to achieve the desired urinary pH
  • Contraindicated in patients w/ alkalosis, hypernatremia, severe pulmonary edema, hypocalcemia & unknown abdominal pain

Tiopronin

  • An active reducing agent that undergoes a thiol-disulfide exchange w/ cystine & forms a tiopronin-cystine disulfide
  • It decreases the amount of soluble cystine in the urine & reduces the formation of cystine calculi
  • Contraindicated in patients w/ prior history of developing agranulocytosis, aplastic anemia or thrombocytopenia

Non-Pharmacological Therapy

Watchful Waiting

  • Since most stones are small, about 5 mm in size, the patient is advised for the passage of stones through normal urination, that usually happens w/in 2-3 days
  • A collection kit is provided w/ filter & the patient is instructed to collect the passed stone for testing & analysis

Diet therapy

  • All stone formers are advised to have a fluid intake that will achieve a urine volume of at least 2.5 liters daily
  • Limit sodium intake & consume 1,000-1,200 mg per day
    • Lower calcium diet in the absence of other specific dietary measures increases the risk of stone formation
  • Limit the intake of oxalate-rich foods & maintain normal calcium consumption
  • Increase the intake of fruits & vegetables
    • Hypocitrituria is common among patients w/ stone disease, w/ a prevalence of 20-60%
    • Promoted by renal tubular acidosis (RTA), chronic diarrhea & carbonic anhydrase inhibitor
  • Limiting the intake of non-dairy animal protein may help reduce stone recurrence
    • Patients w/ a history of uric acid stones should be counseled to:
      • Increase the intake of alkali & decrease the intake of acids
      • Increase the urine pH
      • Reduce the urinary acidity
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