Kidney Stones (Nephrolithiasis)


Kidney Stones (Nephrolithiasis)

January 5, 2006

One of the most humbling physical experiences humans have had to endure since the beginning of recorded history involve the suffering caused by an attack of kidney stones, termed renal colic. The pain has been variably described as being equivalent to childbirth without anesthesia or getting stabbed repeatedly in the back with a large sharp knife. Ironically, it is when the stone is passing that the pain from the stone is most intense with larger immobile stones often asymptomatic. In the past and in many developing countries still, these stones and pain can cause kidney damage and ultimately death. Today this is very rare in patients who are seen by a urologist and treated appropriately for the kidney stones. Although physicians have developed very sophisticated technologies to treat stones some of the most basic questions such as why we form stones remain unanswered in most cases.

How did this happen?
Patients often wonder, how does a hard firm rock get inside their kidney. The natural laws of physics and chemistry help to explain this. Just as under the right conditions water can crystallize and become ice, under the right conditions in the kidney, substances such as calcium that would normally be dissolved in urine can clump together and crystallize. The body does secrete natural inhibitors of this but under the right, or perhaps more appropriate, the wrong conditions these inhibitors can be overwhelmed and crystallization of these previously dissolved substances can happen rapidly and go unchecked. Still much remains unknown and waiting to be discovered. For example, some patients will only form stones in one kidney, other patients who have all the right conditions for stone crystallization never form stones, while other patients who have minimal risks will form recurrent stones. Genetics, anatomy, diet all likely play a role, although their precise contribution is still not completely understood.

Most patients who develop renal colic describe it as an intermittent, excruciating pain originating in their flank and often moving with time to their front side and towards their groin. Patients suffer from pain when the stone falls further into the tube that carries urine, the ureter, and block it. The tube becomes distended with urine behind the stone similar to how plugged drain will overflow with water. This distention activates exquisitely sensitive nerves that carry pain signals back to the brain and ultimately can cause misery. This pain is often accompanied by nausea and vomiting and sometimes by blood in the urine. If an infection also occurs behind the blocked ureter the patient may suffer from fevers and chills and need urgent decompression of the blocked tube. These patients should go to their doctors or the emergency room where they will usually get standard diagnostic tests such as urine and blood test as well as either x-rays, a kidney ultrasound or a CAT scan. Patients will usually be given pain medications and can often be treated as an outpatient. Occasionally, however, they may require a temporary tube to drain the kidney and relieve that pain or to be admitted to the hospital for immediate treatment of the stone.

How do we treat kidney stones?
In the past most patients were advised of two ways to treat stones – either wait until the stones pass or perform open surgery with a large incision to remove the stones. Both of these involved pain or prolonged recovery periods.

Fortunately, today we have many newer technologies to help treat stones. One of the great breakthroughs has been our ability to harness ultrasonic shock waves and focus their energies on breaking stones. There are no cuts to the skin or instruments inserted into the body as the shock waves generator is placed on the skin of the back near the affected kidney. Originally, patients were placed in a large bathtub of water while these shock waves were directed through x-rays at breaking apart the stone. Since then, newer generation of shock wave machines which are used at The Brooklyn Hospital Center have been developed that are more portable and do not require a bathtub. These newer machines also permit more directed energy at the stones with less damage to the nearby tissues. Ultimately, once the larger stone is broken apart by the shock wave machine the hope is that the smaller stone fragments will be able to pass more easily, with minimal pain, through the urine.

For appropriately selected patients who may not want to pass possible painful stone fragments after shock wave, high definition lenses and focused light sources have allowed urologist to enter the urinary tract and follow it all the way up to the kidney where the stones can be directly seen and broken apart using a very small laser fiber. Fragments can be pulverized using the laser leaving only dust behind or, alternatively, removed using a tiny stone basket.

Occasionally, however, patients can develop gigantic, infected stones that occupy the entire collecting system of the kidney – these stones are appropriately termed “staghorn calculi” (see image bottom left). While these stones would have invariably been treated with open surgery in the past, today they are most often removed using a small scope that can be inserted through a half inch cut in the back with much less pain for the patient.

Ultimately, these technological breakthroughs serve the purpose of allowing us to treat all types of kidney stones with less invasive, less painful ways to allow patients to get back on their feet quicker and risk fewer complications.

How Can I Prevent this from happening again?
Many patients who have had a kidney stone often ask if there is any way to prevent stones from forming in the first place. Some stones may be related to the type of medication that patients take and stopping these may help. Other stones may be prevented by changing the acidity of urine to make the environment less hospitable to forming the stones. While urologists have urinary and blood tests that can aid in determining what factors may have predisposed a patient to forming kidney stones, often the exact mechanism is unclear. The large majority of kidney stones are composed of calcium and these stones can be particularly difficult to prevent. General guidelines that have been shown to decrease the chance of forming stones are to reduce the amount of salt in the diet, avoid high protein diets with lots of meat, and increase intake of citrus products such as lemonade, oranges, grapefruit juice as much as possible. While drinking large quantities of water is probably not helpful in preventing stones, it is important for people who have formed kidney stones to prevent dehydration from occurring as much as possible. If these more conservative measures fail and stones recur, patients may be eligible to take generally well-tolerated medications that will reduce the likelihood of forming more stones. Nothing is foolproof, however, and patients who have formed stones and their doctors should remain vigilant for any signs of stone formation and consider periodic screening tests to find stones before they become symptomatic.

For as long as recorded history, humans have suffered through kidney stone
pain. While we still don’t know all the mysteries of these stones, we have fortunately developed modern techniques to help diagnose and treat this ancient condition.

If you have any questions or think you might need treatment for stones, you can contact The Brooklyn Hospital Department of Urology at (718) 250-6880.

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