Kidney Stones

     Kidney stones are a very common medical disorder. About 10% of Americans will sometime in their lives have a kidney stone with more than a million cases being diagnosed each year. In Florida, in particular, is part of what is known in medical circles as a stone belt, an area in the southeast where many patients get kidney stones. This is due to excess mineralization in the water and also because of the warmer climate, people will sweat more, and their urine will therefore be more concentrated, and they will be more likely to form stones.

     The stone that stays in the kidney is commonly asymptomatic. As the stones travel down the ureter, the tube that drains the kidney into the bladder, they will often become stuck. There are three main places in the ureter where this is likely to happen. The first is at the UPJ, which is the junction of the renal pelvis to the ureter. Also, in the mid ureter just overlying the bony pelvis where the ureter is kinked as it crosses over the common iliac artery. The narrowest portion of the ureter is at the junction with the bladder, and this is where stones are most common to get obstructed.

     With all the internal organs of the body, distention is what activates the pain receptors. When the ureter becomes acutely distended because of obstruction, the patient will experience pain, first higher up, and then down lower as the stone progresses distally. Stones that are stuck at the bottom level can also cause urinary symptoms such as urgency and frequency, and even pain in the inner thighs, labia or scrotum.

     Ureteral stones are often able to pass on their own if they are less than 5 mm. At 5 mm 80% of stones will pass, but at 6 mm 40% of stones will pass. Patients who get stones frequently can sometimes have their ureter dilated by repeatedly passing stones and can pass larger stones. Once the stone gets over 5 mm, most people will require intervention.

     Intervention is required in cases in which patients have severe pain, and the pain medication that is taken by mouth will not help, or extreme nausea and vomiting or especially if they have a fever with obstruction. This can become a life-threatening emergency and is the strongest indication for stone intervention.

     Initial treatment is with increasing urine output as much as possible to help the stone form and also to take pain medication as needed. CT scans and other x-ray studies are used to identify the progress that the stone is making as well as to identify stones. Intervention may involve extracorporeal shock wave lithotripsy in which the patient lies over a shock bed and, under anesthesia, a small pressure wave is created outside the body that is concentrating on the stone. It requires anesthesia, but does not have any incision into the patient.

     Another common treatment is to do ureteroscopy; that is, with the patient asleep. Ureteroscope is passed all the way up the ureter through the urethra and laser treatment can be used then to break the stone. Many patients who have this procedure done will require stent placement. A stent is a plastic tube that must be removed in the office at a later time or else it too will become a giant kidney stone.

     In terms of prevention, about 85% of stones are calcium oxalate stones. Oxalate is present in nuts, peanuts and other plant-type foods and is much more important than the calcium level in contributing to stones. No matter what kind of stones one has had, increasing the urine output enough to make one half gallon of urine a day is fruitful. Also, it is good to have high levels of citric acid. This is easily added to the diet in the form of concentrated lemon juice, and 4 ounces per day is recommended and required. Other tests can be done on the urine on someone who has made a stone to see if other specific recommendations can be made to prevent further stone formation.

     About 50% of patients who have a stone will make another one within five years, so usually after someone who has made a stone, we would recommend a 24-hour urine collection in which case the patient’s urine is safe for an entire day and analyzed by a laboratory to find out what chemical constituents of the urine are contributing to stones. This may lead to more specific treatment to prevent other stones. Also, a few simple blood tests can be done to facilitate this process as well.