Kidney Stones
A very large 7mm kidney stone One in 10 people are diagnosed with kidney stones during their
lifetime. The peak incidence occurs between the ages of 30 to 45.
Patients will often present with sudden onset of severe intermittent
pain and nausea. Treatment depends upon stone size, location,
composition and comorbidities. Stones less than 4 mm usually pass
spontaneously while stones greater than 4 mm usually require
intervention. Stones that are unable to pass are generally treated on an outpatient
basis at a urological ambulatory surgery center. A urology-focused
ambulatory surgery center offers cutting-edge minimally invasive
technology necessary to treat all types of stones. For example, a
holmium laser can provide a focused beam of light to fragment stones
with pinpoint accuracy. Latest-generation shockwave lithotripsy
machines (ESWL) offer exceptional radiographic imaging necessary to
maximize success. These machines work by focusing high-energy
shockwaves on the stone while minimizing trauma to surrounding tissue.
A urology-specific surgical center will also have the full array of
endoscopic equipment such as miniature ureteroscopes, which can be
placed through the urethra and advanced all the way up in to the kidney
itself to visualize stones for fragmentation. When stones are larger,
more invasive procedures are generally necessary, such as a
percutaneous nephrolithotomy (PCNL), where the stone is fragmented and
removed through a small puncture made through the flank.
Unfortunately, many stones formers do not receive the appropriate prevention after the acute stone crisis has resolved. With correct preventive dietary counseling and selective medical therapy, a stone remission rate of 90% can be achieved. Risk factors for recurrent stone formation includes young age, gender (male), race (Caucasian), family history of stones, recurrent urinary tract infections, gout and osteoporosis. The cornerstone of prevention involves a chemical stone analysis, basic blood work and a 24-hour urine collection. The two most common stones are composed of calcium oxalate (82%) or uric acid (8%). A careful dietary history and review of all over-the-counter and prescription medications should also be completed.
Low-to moderate-risk stone formers will have an excellent result
with dietary and fluid management alone. All stone formers should
increase their urine output to greater than 2,500 cc. Calcium oxalate
stone formers should avoid foods high in oxalate such as chocolate,
nuts, black pepper and spinach. If patients have a history of
osteoporosis or osteopenia they should stay on calcium supplementation
with calcium citrate. If not, then calcium supplements should be
avoided unless a screening bone density test later reveals problems
with low bone density. A low-salt diet will further reduce the risk of
future stones. Increasing dietary citrate with fresh lemon, lime,
orange or pineapple juice will also inhibit stone formation.
People who form uric-acid stones should follow a low-purine diet and
minimize intake of beef, fowl and shellfish. Uric-acid stone formers
often require urinary alkalization with medications such as potassium
citrate. The goal of alkalization is a urinary pH between 6.5 to 7.0.
Uric-acid stones often cannot be visualized on routine X-rays and
therefore require diagnosis by CT or ultrasound. Unlike the more
common calcium-based stones, uric-acid stones can often be dissolved
with medical management without the need for surgical intervention.
All patients with kidney stones should be referred to a urologist for management and prevention. High-risk stone formers generally placed on long-term medical therapy and dietary restrictions. These patients are followed up on an annual basis for routine X-rays, urinalysis and repeat 24-hour urine collections.
Kidney stones can be a very painful and often recurrent problem. Sudden onset of severe pain often occurs at the worst possible times. Kidney stones often are caused by underlying metabolic disorders and proper evaluation is essential for stone prevention.