Prevention

Fluid Intake About 1.6 L/24 h Encouraged during mealtime Increased approximately 2 h after meals Encouraged to force a nighttime diuresis Water produced as a metabolic by-product reaches its nadir at this time, and thus the body is relatively dehydrated. Awakening and ambulating to void limit urinary stasis and offer an opportunity to ingest additional fluids.

Metabolic Intervention Stone analysis Outpatient urine collection during typical activities & fluid intake Ca stone formers Initial 24-h urine collection Include tests for Ca, uric acid, oxalate, citrate, Na, volume, & pH Hypercalciuria: most common abnormality

Oral Intervention Alkalinizing pH agents Potassium citrate: oral agent that elevates urinary pH effectively by 0.7–0.8 pH units Adverse effect: abdominal discomfort Indications: Ca oxalate calculi 2° to hypocitraturia (<320 mg/day), including those with renal tubular acidosis; uric acid lithiasis & nonsevere forms of hyperuricosuric Ca nephrolithiasis. Alternative alkalinizing agents: Na, potassium bicarbonate, orange juice, & lemonade No effective long-term urinary acidifying agents

Oral Intervention Gastrointestinal absorption inhibitor Cellulose phosphate binds Ca in the gut & inhibits Ca absorption & urinary excretion Decreases urinary saturation of Ca phosphate & Ca oxalate Phosphate supplementation Indicated for renal PO4 leak

Oral Intervention Diuretics Thiazides can correct renal Ca leak associated with renal hypercalciuria Prevents 2° hyperparathyroid state & its associated elevated vitamin D synthesis & intestinal calcium absorption Hypokalemia  hypocitraturia

Oral Intervention Calcium supplementation Indication: Enteric hyperoxaluric Ca nephrolithiasis Ca gluconate & Ca citrate Uric acid-lowering medications Allopurinol Urease inhibitor Acetohydroxamic acid: effective adjunctive treatment in chronic urea-splitting urinary tract infections associated with struvite stones Prophylaxis after removal of struvite stone Reversibly inhibits bacterial urease, decreasing urinary ammonia levels, and will subsequently acidify urine

Oral Intervention Prevention of cystine calculi Penicillamine: reduces the amount of urinary cystine that is relatively insoluble Mercaptopropionylglycine (Thiola)

Bladder Stones

Bladder Stones Manifestation of an underlying pathologic condition, including voiding dysfunction or a foreign body Most seen in men Developing countries: frequently found in prepubescent boys Stone analysis: ammonium urate, uric acid, or Ca oxalate stones Irritative voiding symptoms, intermittent urinary stream, UTI, hematuria, or pelvic pain

Prostatic Stones Prostatic calculi: found within prostate gland per se & are found uncommonly within the prostatic urethra Represent calcified corpora amylacea & rarely found in boys Usually of no clinical significance, rarely they are associated with chronic prostatitis Large prostatic calculi: may be misinterpreted as a carcinoma Dx: radiograph or transrectal ultrasound

Seminal Vesicle Stones Smooth & hard Associated with hematospermia PE: stony hard gland; multiple stones present with crunching sensation Confused with tuberculosis of the seminal vesicle

Urethral Stones Originate from bladder Develop 2° to urinary stasis, urethral diverticulum, near urethral strictures, or at sites of previous surgery Females: rarely develop urethral calculi due to short urethra & lower incidence of bladder calculi; associated with urethral diverticula Symptoms : intermittent urinary stream, terminal hematuria, & infection Dx: palpation, endoscopic visualization, or radiographic study

Prepucial Stones Occur in adults Develop 2° to a severe obstructive phimosis or poor hygiene with inspissated smegma Dx confirmed by palpation Tx: dorsal prepucial slit or formal circumcision