Kidney Stone Disease

Overview

The urinary tract rids the body of urine or liquid waste that is collected in the kidneys through long, narrow tubes called ureters.  The urine drains into the bladder where it is stored until you are ready to urinate.  It then leaves the body through the urethra.  Chemicals in the urine can sometimes form crystals that have an appearance similar to sand.  If these crystals stick together they become a hard mass or stone.  The stone can get stuck in the kidney or ureter that could block urine from getting to the bladder, which causes severe pain.  Knowing the type of kidney stone you have helps to determine the cause and will provide ways to reduce your risk of getting more kidney stones.

Calcium stones.  Most kidney stones are calcium stones, usually in the form of calcium oxalate.  Oxalate is a natural substance found in food such as some fruits, vegetables, as well as nuts and chocolate.  Your liver also produces oxalate, so dietary factors, intestinal bypass surgery and several metabolic disorders can increase the concentration of calcium or oxalate in urine. 

Struvite stones.  Struvite stones form in response to an infection, such as a urinary tract infection.  These stones can grow quickly and become quite large.

Uric acid stones.  Uric acid stones can form in people who do not drink enough fluids or who lose too much fluid.  People that eat a high-protein diets or have gout have a higher risk for uric acid stones.

Cystine stones.  Cystine stones form in people with a hereditary disorder that causes the kidneys to excrete too much of certain amino acids (cystinuria).

Urology Associates of Central California is the only facility in the Central Valley that has an Extracorporeal Shockwave Lithotripsy (ESWL) machine on-site for the destruction of kidney stones using sound waves.  All of our urologists are expert stone surgeons using a variety of techniques and modalities to help our patients with kidney stones disease.  Fortunately, most stones pass out of the body without any intervention.  Patients with kidney or ureteral stones may be treated with behavioral modifications, medical therapy, or surgery.

Behavioral Modifications

Unfortunately, kidney stones are a recurrent disease, meaning if you have one stone you are at risk for another stone event.  In general, the lifetime recurrence risk for a stone former is thought to approach 50%, thus stone prevention is essential.  For stones less than 4 mm in size, a trial of passage may be used to try and get you to pass the stone on your own along with some key behavioral medications. 

Increase Hydration

Any patient that has stones or is at risk for stones will be asked to drink more liquids, and water is always the best.  If you tend to form stones, you should try to drink enough liquids throughout the day to produce at least two liters of urine in every 24 hour period. 

Dietary Changes

Diets high in calcium, sodium and oxalates can increase the risk of certain types of kidney stones.  You must decrease your sodium intake to avoid future kidney stones.  The table below shows you the type of foods to avoid depending on the type of stone you have, or have had in the past. 

Calcium or Oxalate Stones          Uric Acid Stones              Struvite Stones                    Cystine Stones

For additional information click this link for our stone prevention diet.

Medical Therapy

Along with behavioral modifications, your urologist may prescribe an alpha blocker for you to relax the muscles in the ureter helping you pass the kidney stone quickly and with less pain.  This type of approach is used for small stones usually measuring 4 mm or less. 

Medical therapy may also be used in stone prevention depending on the type of stones.  To help prevent calcium stones from forming, you may be prescribed a thiazide diuretic or a phosphate-containing preparation.  For uric acid stones, you may be prescribed Allopurinol and an alkalinizing agent to attempt and dissolve the uric acid stones.  To prevent struvite stones, you may be prescribed long-term daily prophylaxis using antibiotics to keep urine free of bacteria that cause these stones.  Cystine stones are difficult to treat.  Your urologist will recommend that you push your fluids so that you produce a lot more urine.  If that does not help, then your doctor may also prescribe a mediation that decreases the amount of cystine in your urine. 

Surgery

The size of your stone(s), number of stone(s), and location are all factors in deciding the appropriate treatment for a patient with kidney stones.  For patients that are asymptomatic, we will frequently try behavioral modifications or medical therapy before operating.  The most common types of surgery

for kidney stones include Extracorporeal Shockwave Lithotripsy (ESWL), Ureteroscopy (URS), and Percutaneous Nephrolithotomy.

Extracorporeal Shockwave Lithotripsy (ESWL)

ESWL is the most common surgery for eliminating kidney stones.  Our facility is the only center in the Central Valley that has its own ESWL machine in our surgery center.  This allows us to operate much sooner if needed, and is more convenient for the patient to have surgery right next door from where you saw your urologist.

ESWL works by directing ultrasonic or shockwaves created outside your body (extracorporeal) through skin and tissue until they hit the dense kidney stones which causes stress on the stone.  Repeated shockwaves cause more stress until the stone eventually crumbles into small pieces.  These sand-like particles are easily passed through the urinary tract in the urine.  The technology is only effective if the kidney is functioning well and there is no blockage to the passage of stone fragments.  Sometimes these stone fragments are large enough and they do not pass, which often need to be treated with additional ESWL treatments.  Often, a stent may be placed up the ureter just prior to ESWL to assist in locating the stone or assist in stone fragment passage following treatment.  You will have anesthesia for an ESWL. 

Certain types of stone such as cystine, and calcium oxalate monohydrate are resistant to ESWL and usually require another treatment.  Larger stones usually greater than 2.5 cm may break into large pieces that can still block the kidney.

Ureteroscopy

This treatment involves the use of a very small fiber optic instrument called a ureteroscope that allows access to stones in the ureter or kidney.  The ureteroscope allows your urologist to directly visualize the stone by progressing up the ureter via the bladder.  No incisions are necessary and general anesthesia is used.  Once the stone is seen through the ureteroscope, a small basket-like device can be used to grasp small stones and remove them.  If a stone is too large to remove in one piece, it can be fragmented into small pieces often done by laser.  You may have a ureteral stent following the procedure to allow any post-operative swelling or reaction to subside.

Percutaneous Nephrolithotomy (PNL)

Percutaneous Nephrolithotomy is the type of treatment needed under general anesthesia for large kidney stones that cannot be effectively treated with either ESWL or URS.  A small incision about 1 cm is required in the flank area of the patient.  The surgeon then places a guide wire through the incision.  The wire is inserted into the kidney under radiographic guidance and directed down the ureter.  A passage is then created around the wire using dilators to provide access into the kidney.  Next, a nephroscope is then passed into the kidney which allows the surgeon to have visualization of the stone.  Fragmentation can then be done  using an ultrasonic probe or laser.  With PCL the surgeon has the ability of passing larger instruments allowing the urologist to suction out or grasp the stone fragments as they are created.  As a result, there is a higher clearance of stone fragments than with ESWL or Ureteroscopy.