- Friday, October 16, 2015
Some Thoughts on Kidney Stones
At Urology Centers of Alabama, we take kidney stones very seriously. We know how painful and disruptive they can be. They never seem to occur at a convenient time, and patients who are at risk for stones never know when the next one will hit. Understanding the various types and causes of kidney stones can sometimes help the patient better understand what might be causing their stones and find ways to try to avoid another one. It is also important to understand the different types of therapy and management options available to the Urologist, so that the patient has some idea of what they might expect if they develop a stone.
There are numerous types of kidney stones, but the most common include: Calcium Oxalate, Calcium Phosphate, or a combination of the two, uric acid , Struvite and cystine stones. Patients may be predisposed to form kidney stones in general because of genetics ( family history ). However, even if a patient is predisposed , it doesn’t mean that they will have a stone. Other environmental and dietary factors also play a role, and become extremely important in helping to find ways to prevent stones. For instance, no matter what type of stone a patient is inclined to form, drinking more water will help keep the stone crystals in solution. If you take a teaspoon of salt and stir it into a quart of water, you will not see any salt crystals in the glass. However, if you put that teaspoon of salt into a small glass of water, you will see some crystals in the bottom of the glass. Keep in mind, however, that sometimes, even the type of water you drink may increase your risks. Some brands of water may actually contain calcium supplements. It is important to check the ingredients on the label.
Another ingredient of food and drinks that could increase stone risk is salt. This is metabolized in the kidneys to push more calcium into the urine. Salt is found not only in salt shakers, but also in many soft drinks, foods ( especially processed meats and canned foods), but also Gatorade and Powerade.
Dairy products usually do not increase stone risk, if taken in moderation. In fact, they sometimes can be useful to prevent stones in certain circumstances. However, calcium supplements should be avoided in calcium stone patients unless specifically required and recommended by your Physician. Calcium supplements may be found in vitamins, Tums/ Rolaids, and added as supplements to many foods and drinks.
Oxalate is one of the components of the most common type of kidney stone ( Calcium Oxalate). It may be found in many products; especially tea, strawberries, dark green leafy vegetables ( such as spinach ), nuts and chocolate. It is usually not necessary to try to avoid all oxalate containing products, but do keep in mind that the more oxalate that is ingested, the stone risk increases.
Patients who develop uric acid stones are managed somewhat differently . These stones are not usually seen on plain x-rays, as they contain no calcium ( except under certain circumstances). This makes it more difficult to visualize the stone during some treatments, but a positive for the patient is that this type stone can actually shrink in size or even disappear if enough water is put around it, or the urine made to become more alkaline. These stones will be more prominent in patients with gout , or in those who have large protein intake, which is metabolized to uric acid, and also have acidic urine.
The management of kidney stones by the Urologist will depend on the type of stone, its size, location and various other factors. If a stone is potentially passable, we might use a pill to relax the smooth muscle of the ureter to allow it to pass more easily, as our preference is usually to allow the patient to pass the stone if possible. If surgery is needed, however, there are various approaches and techniques and equipment which can be used.
If the stone is in the kidney, we might consider ESWL ( lithotripsy), which delivers external shock waves to the stone under anesthesia or heavy sedation to fragment it into passable pieces. Or we might use a laser form of lithotripsy thru a small scope which can be passed up the ureter from below, or occasionally thru special tubes thru a small hole in the side if the stone is too large. Sometimes, we will also use a small flexible tube that will remain in place after the surgery , extending from the kidney to the ureter, to help urine pass down to the bladder despite residual fragments, blood or swelling. This tube is inside the patient and usually left in place for a week ( sometime less, sometimes more ). This might cause increased sensations to urinate more frequently and urgently , and may cause some kidney pain during urination, which might last several minutes and also increases the incidence of blood in the urine. These are all expected and usually tolerated relatively well with medication, but certainly preferable to the increased risk of having to go back to the ER for severe pain. Obviously, we try to avoid placing the stents if possible.
Our focus is also on trying to find ways to help the patient avoid recurrent kidney stones. There are certain blood and urine labs which may be utilized to determine increased risk of having a stone. There is a particular focus on this in our Stone Prevention Clinic, which may be especially helpful for those patients who have had multiple stones or are not responding to the usual prevention measures. There are also medications which may be used for certain circumstances to help avoid stones. As you can see, stones are a complex medical problem, but we enjoy the challenge of not only relieving our patient’s suffering , but also in finding ways to help them avoid recurrent problems.
Rodney Dennis MD