Dr. Lester Wang on Kidney Stones
Hi, I am Dr. Lester Wang, I am from the Urology team. I am a urologist specializing in the kidney stones or endo-urology.
The urinary tract is composed of the kidneys which filters the blood to make urine, the urine travels from the kidneys to the bladder through the ureters, it stored in the bladder and patient pour it out through the urethra.
Kidney stones formed where there is excess in various minerals, salts and there is a imbalance. The most common cause for the kidney stones is most likely the dehydration, there is a increases with increase in sodium intake because the kidney work by spilling in calcium when you take in sodium, urinary tract infections is also associated with kidney stones.
Most stones are composed of calcium, the most common being calcium oxalate, there is also calcium phosphate these are probably the two most common stones. Uric acid stones and struvite stones which are stones caused by infections. And cystine which is inheritable amino acid disorder.
So here is an illustration of different types of kidney stones of which this is calcium oxylate. Calcium oxylate stones can vary in size and they can be quite painful and if you can see this top right picture here, this stone is what's called jackstone probably one of the hardest to retrieve.
The next slide shows the calcium phosphate stones and actually the picture on the top left shows calcium phosphate stones within a kidney.
Uric acid stones are basically same type of salt seen in the patients with gout, but not all patients with gout will have uric acid stones, only about 20% of the patients with gout will have uric acid stones. And uric acid stones can often be retrieved with medication and often don't require surgery.
The next stones are struvite stones, struvite stones are associated with infections, the top two pictures are actually struvite stones which have been removed from kidneys and they are actually a cast of the collecting system of the kidney. The bottom stone is a stone that has been removed from the bladder, and you can see it is quite big and it will be very difficult to try and pass this spontaneously.
Next picture is a picture of a cystine stone, cystine stone is inheritable amino acid disorder and these stones are quite hard and often form will form the full cast of the kidney. You may not know that you have a kidney stone, many stones are asymptomatic. You can have pain in your flank, you can have pain in abdomen, groin, nausea and vomiting may be associated with it, hematuria or blood in urine and you if you have high credit blockage in it you can have fever and chills.
How your physician figure out if you have stones? A physician will ask you questions about your pain and what's been going on with you lately. Then physician will take a look at your urine, and perform a urine analysis in microscopic exam in which he will look for puss and blood. And he will also get some X-ray studies, the most common today is CT scan of the abdomen and pelvis and another way is intravenous pyelogram.
So here is a picture of an IVP, the right side, your right side is the patient's left side, and on right side there is a complete stake on cal stone. It is a big stone, it is about the size of a fist. And a dye is given and you can see that the left kidney does not work as well as the right the right kidney is excreting dyeing. That's not a stone on the right here, that is the patient's right, your left, that is actually dye going through the kidney.
Next picture shows the same patient but this is a CT scan and in the bottom right you can see this kidney stone which is almost completely filling the kidney collecting system.
So, how do we treat them? the best thing is don't get them. How do you not get them? Water, water, water. Lemonade which has citrate and citrate is a known inhibitor of kidney stone formation and low sodium. The kidney works by spilling a calcium when it picks up a sodium. And basically in kidney stone diet is moderation, try and decrease your meats, proteins and your oxalate consumption which is in nuts, berries and green leafy vegetables. Obesity is becoming an increasing problem in United States and with obesity comes kidney stones because when a person eats too much, they gain weight and when they gain weight there is an excess and the body needs to get rid of this excess. And so the excess is spilled out in urine and with this excess come kidney stones.
So when we treat kidney stones, if we can prevent them we prefer patients to pass them. Most patients will be able to pass a small stone and as a general rule of thumb a 5 or 6 millimeter stone has a 50% chance of passing without any intervention.
There are some medications which we can give that will relax the ureters and the urinary tract to increase the spontaneous passage rate.
In terms of surgical options, Extracorporeal Shock Wave Lithotripsy or ESWL has revolutionized the treatment of kidney stones. This is generally used for stones less than 2 centimeters in size. And stones are broken up with water waves and patients would go - what the heck do you mean by water waves? In this next illustration, you can see this man on the left here and he is punching through this membrane and behind this membrane is water and through this water this little waves will form. So the waves formed through the water are focused on the kidney stones and they help disintegrate the stones, they penetrate through the body without damaging the tissues. And they make the stones small enough that the patients can pass them.
Next picture here shows the basic lithotripter, in which a patient lies on the table and behind him there is a column of water and there is a source for power to be generated to cause the water wave and this is a shock wave generator here at the very bottom and these water waves are focused upon the kidney stone. The Dornier HM3 was the first lithotripter that was FDA approved for use in United States and this machine was a couple of million dollars, I don't know the exact amount but it used to take up a whole room. And this little silver top is actually the size of a bath tub, and the patient is lowered into the water and it was very cumbersome twenty years ago. Now we have portable machines which can be transported with small rants and can be moved from hospital to hospital.
So the advantages of use of ESWL are non-invasive and it can be done as out-patient but there are some problems, may be require multiple procedures, it is only good for stones less than 2cm in size in general and it may increase the risk of hypertension or diabetes and some stones may not break up.
So another option that we have is to place a scope into the urinary and kidney called ureteroscopy and breakup the stones with a laser. And this laser can be used to break the stones into smaller pieces and we can have patients pass them or we can grab them.
In this picture here on the left, this is artist's indication of what's going on the right, the scope is going up all the way through the bladder, through the urethra and into the kidney and we can utilize this to break-up the stone and this is a rigid type scope. With the advent of fiber-optics, we now have flexible scopes which we can now treat stones in different parts of the kidney.
Here is a picture of a actual ureteroscopy in which we are inside the urethra and we are looking at this brown object here which is a stone and on the left is a little wire, we can actually put a laser on to the stone and break it up into small pieces.
Ureteroscopy laser substitutes we have many advantages - you know what happens sooner with the stone, there is no incisions and it can be done at out-patient surgery. The disadvantages are there, it is invasive, it may not be effective for a very large stone burden and stricture or scar tissue formation can occur inside the urethra or inside the kidney. And there is a possible need for a stint, which is a drainage tube which can be quite irritating.
So, here is cartoonish indication of how to break up kidney stones, where people go - well while using a jack hammer to break up the kidney stone. We actually do have a jack hammer that breaks up a kidney stone. This is a picture of a ultra-sonic Lithotripsy here and it is basically a medical jack-hammer, in which a stone can be broken and fragments can be sucked up through the middle. Here is a video from olympus inside the kidney and is actually breaking up the stone.
So the best treatment for the kidney stones, prevention - water, water, water. We can do metabolic work up, we can look at what spilled in urine, reduce blood work, basically patients need to drink more water, some lemonade would be helpful, modify your diet, diet with moderation and at times we can help the patients with medication.
Thank you.