Kidney stones

Depending on where the stone is located, it is also referred to as kidney stones (nephrolithiasis), ureteral stones (ureterolithiasis) or bladder stones (cystolithiasis). Sometimes kidney stones are only as small as the head of a pin. Other kidney stones grow to several centimeters in size and can even fill the entire urinary cavity. Urolithiasis can usually be treated well. Most commonly, kidney stones are dissolved spontaneously through urine. Certain kidney stones can be dissolved with medication. Rarely, kidney stones need to be treated with surgery.

Overview: What are kidney stones?

Kidney stones form from tiny crystals that are excreted by the kidney every day and are usually dissolved in urine. When there are too many crystals in too little urine, kidney stones form. The most common crystalline composition is calcium and oxalate. Under certain conditions, kidney stones can also form from uric acid, phosphate, cystine or from other rare crystalline elements.

Kidney stones – frequency and age

About ten percent of the Swiss population is affected by a kidney stone. In most cases, kidney stones go unnoticed. However, every year, approximately 25,000 to 40,000 Swiss people suffer from a painful kidney stone. That is about 300 to 500 affected persons per 100,000 inhabitants. Kidney stones form more frequently in men than in women. Kidney stones are most common between the ages of 30 and 60.

Regardless of their age, around 650,000 to 1.3 million Swiss people can expect to develop kidney stones at some point in their lives. About half of them will statistically suffer from urolithiasis again within ten years. This is especially true if those affected by kidney stones do not take precautions against recurrence. However, with preventive measures (drinking plenty of fluids, eating the right foods), the risk of developing the disease can be significantly reduced.

Kidney stones: causes and risk factors

Why kidney stones form can usually be determined by examination. In general, several risk factors are known to promote the development of urolithiasis:

• Low fluid intake. If you don’t drink enough, the amount of water in your urine decreases. In turn, the concentration of certain substances (for example calcium) increases in the urine. They crystallize and become kidney stones.
• Lots of oxalate. Much of the oxalate dissolved in urine each day comes from our own liver. The liver produces oxalate as an end product of various necessary metabolic pathways and is excreted in the urine. In addition, certain foods may cause significant additional excretion of oxalate. Either the foods contain a lot of oxalate, or they increase oxalate production by the liver. Examples of oxalate-rich foods: rhubarb, spinach, chard, almonds and nuts. Examples of foods that cause overproduction of oxalate by the liver: Sweetened beverages (especially soft drinks containing fructose) and gelatin-based gummy candies. Excessive excretion of oxalate in the urine can promote the formation of kidney stones. In this case, they belong to a subgroup of kidney stones called calcium oxalate stones.
• Lots of salt. A salt intake of less than five grams of salt per person per day is recommended by the World Health Organization (WHO) for the prevention of cardiovascular disease, the leading cause of death worldwide. This salt intake limitation is also relevant in kidney stones: high salt intake causes excess excretion of calcium in the urine. This results in a very high concentration of calcium in the urine, which promotes the formation of calcium oxalate stones and calcium phosphate stones.
• Protein-rich diet. Meat, fish, seafood, eggs and certain food supplements (e.g. soy shake) contain particularly high amounts of protein. A protein-rich diet causes a significant acid load on the body. The acid load is rapidly balanced in our bones, and later excreted through the kidneys into the urine. The resulting highly acidic urine accelerates the formation of kidney stones containing uric acid. These stone-challenging conditions are especially strengthened when meat and fish are consumed, because these foods can cause additional uric acid excretion in the urine. In this case, they belong to a subgroup of kidney stones, uric acid stones.
• Certain diseases. Various metabolic disorders can promote the development of kidney stones. For example, hyperparathyroidism causes increased calcium to be released into the urine. Diabetics also have an increased risk of kidney stones; their urine is too acidic, which promotes the formation of uric acid stones (similar to excessive protein consumption, see above). One particular condition can cause kidney stones to form early in life: cystinuria. This hereditary disease requires a lifelong adapted diet and drinking behavior.

There is also a generally increased risk of kidney stones if you have a family history of kidney stones or if you have had kidney stones yourself.

Symptoms: Kidney stones

Kidney stones are not immediately noticeable. As long as they remain immobile in the kidney, they usually do not produce any symptoms.

Only when kidney stones migrate into the ureter and prevent the outflow of urine does pain occur. The pain occurs because the back up of urine increases pressure in the kidney and causes renal colic. Renal colic is manifested by sharp, stabbing, cramping pain in the lumbar region. Radiation of pain to the groin or external genitalia is possible. Typically, the pain intensity decreases within a few minutes until the pain returns.

If you experience renal colic, the pain may become so unbearable that you vomit. Typically, any body position change or back rest does not help improve the pain.

Depending on the duration and severity of the congestion, the kidneys may be damaged, which can lead to complete loss of kidney function. In addition, urine outflow obstruction poses an increased risk of infection, even life-threatening blood poisoning.

As nephrolithiasis progresses, kidney stones can migrate to the urinary bladder and from there into the urethra. If they injure the mucous membranes of the urinary tract in the process, your urine may contain blood.

Kidney stones: Diagnosis with us

Your kidney stones (urinary stones) may be discovered only by chance, for example, during an ultrasound examination. However, you may have kidney stones that are causing discomfort and that is why you are seeking us out. In both cases, an examination should clarify the more detailed circumstances of your nephrolithiasis.

If your kidney stones are causing pain, we want to make sure your discomfort is not from another condition. Pain similar to that caused by kidney stones can also occur, for example, with appendicitis, gallstones, intestinal obstruction or inflammation of the pancreas.

A blood test can tell us how functional your kidneys are. A urine test will show if you have a urinary tract infection.

However, kidney stones cannot yet be diagnosed with it. Imaging will need to be used to clarify the details of your nephrolithiasis. The following methods are available:

• Ultrasound (sonography). With this examination we can see how many kidney stones you have, where they are located and how big they are. Sonography can also provide information about your kidney function and any urinary retention. Ultrasound examination is painless and does not cause any side effects.
• Computed tomography(CT). This examination can be used to determine the size of kidney stones particularly accurately. This is especially true for small stones. Computed tomography uses X-rays.
• Excretory Urography. During this examination, a contrast medium is administered to you with a syringe. It enters the kidneys through the blood and is excreted through the ureters and bladder. These organs can be visualized on X-ray images. For example, we can tell if (or where) a kidney stone is preventing urine from flowing.

We may also want to know what type of kidney stones you are dealing with. A kidney stone analysis can clarify this. If you discover an excreted kidney stone in your urine, you should pick it up, rinse it with water and show it to us.

Kidney stones: prevention, early detection, prognosis

Since there are risk factors that promote the development of kidney stones (urinary stones), you should be aware of these risk factors and avoid them if possible. Experts call this “stone prophylaxis”. Even with a few simple preventive measures, you increase the likelihood of not developing nephrolithiasis (again).

The following preventive measures against kidney stones will help you reduce the risk of nephrolithiasis:

• Drink a lot. If you drink at least two liters of fluid a day, you can prevent your urine from becoming so concentrated that stones form in it. Drink at all times of the day, if possible, and if you are awake, also at night. However, to be on the safe side, ask us if there are any objections to taking fluids in larger amounts and if there is an upper limit for you.
• Eat a balanced diet. If you eat little meat and sausage, you reduce the likelihood of uric acid stones forming in your kidneys. And if you avoid larger amounts of foods that contain oxalic acid (these include rhubarb, spinach, Swiss chard, almonds, and nuts), you lower your risk of developing calcium oxalate stones, a subgroup of kidney stones.
• Make sure you get enough exercise. Aside from being generally good for your health, exercise may prevent small kidney stones from lodging.
• Avoid being overweight. However, when losing weight, make sure that you do not choose a strict, one-sided diet, but eat a balanced diet. Extreme diets could promote the formation of kidney stones.

Kidney stones: course and prognosis

Your kidney stones may leave your body on their own. In such a case, experts speak of a “spontaneous departure”. Small stones in particular, whose diameter is less than about four millimeters, are often excreted by themselves in the urine. Very small kidney stones are also called kidney stones.

If you are lucky, no further kidney stones will occur in you afterwards. However, in about half of all kidney stone patients, nephrolithiasis recurs. You can reduce the risk of this if you observe the precautionary measures mentioned.

In most cases, kidney stone diseases can be treated well and take a favorable course. Nevertheless, complications may occur in isolated cases. They occur mainly when the kidney stones prevent the outflow of urine. Then the urine that continues to be produced by the affected kidney accumulates, along with the toxins it contains. They can damage kidney tissue. In addition, urinary bacteria present in accumulated urine multiply. In this way, kidney stones can indirectly lead to serious complications:

• Inflammation of the renal pelvis. This disease is called pyelonephritis. Chronic inflammation of the renal pelvis can lead to a shrunken kidney in the long term.
• Inflammation of the urinary tract (ureter, bladder, urethra)
• Blood poisoning, also sepsis It occurs when bacteria enter the bloodstream. In this case, experts speak of urosepsis because the bacteria originate from the urogenital tract, i.e. from the area of the urinary and genital organs.
• Acute kidney failure, also known as acute renal insufficiency If a kidney stone blocks the outflow of urine, the kidney can stop functioning in rare cases. This situation is also called postrenal renal failure (postrenal means after or behind the kidney).

Kidney stones: effective treatment

Kidney stones do not always need to be treated. This is especially true for smaller stones that are excreted in the urine. However, you should see us if your kidney stones do not go away on their own, if they cause pain, if a kidney stone causes a urinary tract infection, or if you have reduced urine output.

There are several ways to treat nephrolithiasis and remove kidney stones:

• Shattering of kidney stones by shock waves. This method is abbreviated with the letters ESWL (extracorporeal shock wave lithotripsy). A device is used to direct focused sound waves at the kidney stone that needs to be removed. The term “litho” stands for stone, and the term “extracorporeal” (outside the body) indicates that the treatment is done from the outside, that is, without intervention in your body. The high-energy sound waves break up the kidney stone. The individual fragments are excreted in the urine. This can take several weeks.
• Removal with an endoscopic procedure – uretero-renoscopy (URS). In this procedure, we insert a fine instrument (ureteroscope) into the ureter via the urethra and bladder. In addition to the light channel for the camera, a ureteroscope also has a working channel, for the introduction of lasers, for example, and an irrigation channel. By means of the urethroscope, small, easily positioned stones can be extracted directly from the ureter or kidney with a small stone catcher without prior crushing. If the stone is too large to remove directly, it is shattered with the laser (Holmium:Yag laser) or finely atomized (Thulium fiber laser).
• Removal with an endoscopic procedure – directly through the kidney. If access to the stone via natural body cavities is difficult with URS, cannot be treated with shock waves, or is very large, it can be accessed directly from the outside via a small skin incision in a single surgery. This method is abbreviated with the letters PCNL (percutaneous nephrolitholapaxy or nephrolithotomy). After a local or general anesthetic, a small incision is first made through the skin near the lowest rib (“percutaneous” means: through the skin). Through this opening, we insert a thin, tube-like instrument, an endoscope, (nephroscope) into the body up to the kidney. Using the nephroscope, the stone can either be removed directly or is shattered into smaller fragments beforehand using a laser.
• Open surgery. Open surgery (i.e., not a minimally invasive procedure through a small incision) is rarely performed for nephrolithiasis today. The surgery may be necessary if the kidney stones have exceeded a certain size or number.
• Medication. They dissolve certain types of kidney stones in some cases. This is possible with smaller stones, which consist of uric acid. The active ingredient of the drug (for example, alkali citrate, sodium carbonate, or allopurinol) can cause the urinary calculus to become alkaline and thus lose its hardness.