The kidneys purify thebody. They filter breakdown products, poisons and other unwanted substances out of the blood. From this “garbage” the kidneys form urine, which the body excretes via the bladder and the urethra.
Normally, these substances are dissolved in the urine. Under certain conditions, however, some of the substances maycrystallizeand accumulate as stones in the urinary tract. Depending on where they are deposited, it is called kidney stones, ureteral stones or bladder stones.
What are kidney stones?
Kidney stones (nephrolites: Greek nephrós = kidney, líthos = stone) are solid structures that form from normally dissolved in the urine substances. Their size can range from a few millimeters (aboutrice grainsize )to several centimeters. Most kidney stones occur onone side.
In western industrialized countries, many people develop kidney stones. In Germany today, about three times as many people get it as they did ten years ago. About five out of every 100 people in the population have urinary stones. They occur particularly often in men between the35th and 65th year of life.
Kidney stones can be divided intodifferent stonetypes depending on the composition :
- Calcium oxalate stonesmake up about80 percent of all urinary stones.
- Uric acid stones (urate stones) (10%)
- Magnesium-ammonium-phosphate stones (struvite stones) – also called infectious stones, as they are associated with a urinary tract infection, 5%
- Calcium phosphate stones (5%)
- rare stones (<1%) such as cystine stones and xanthine stones
Kidney stones: Symptoms usually appear late
Whether and what symptoms occur depends on thesize and location ofthe kidney stones.Small kidney stonescango unnoticedthrough the ureter into the bladder and get out while urinating.
Larger kidney stones, on the other hand, can touch the wall of the ureter and even get stuck in it. This can causeviolent spasms or labor-like, stinging pains(so-called uretercolic). They usually start in the flank and radiate along the ureter into the lower abdomen.
Deep-seated kidney stones caneventrigger pain radiatinginto the genitals(scrotumorlabia). As the stone moves slowly through the urinary tract, pain also often moves with it.
In addition, if a kidney stone injures the wall of the ureter,bleedingmay occur. When the stone passes into the urinary bladder and then into the urethra, there is often so muchblood in the urinethat it can be seen with the naked eye (so-calledgross hematuria).
Kidney stones: causes and development
Whether a human develops kidney stones depends primarily on thecomposition of his urine. The decisive factor is above all:
- the amount of stone forming substances in the urine,
- the amount of so-called stone formation inhibitors (lat inhibitor = inhibitor) in urine and
- the acidity of urine (pH).
Too high a concentration of stone-forming substances
If certain substances in the urine exceeda certain concentration, they become solid crystals. When, over time, layers of new layers are attached to the crystals on the onion-peel-like scale, kidney stones develop. The substances that can form kidney stones include:
- Oxalate (salt of oxalic acid),
- Uric acid as well
Too few inhibitors
The urine ofhealthy peopleis sometimes supersaturated with one or some of the substances mentioned. They, too, form crystals – butthe body normally excretesthemunnoticedwithout forming kidney stones.
This is because the urine of healthy people contains substances such as citrate and magnesium,which inhibit the formation of stones. In contrast, people susceptible to kidney stones oftenhave very low levels of such inhibitorsin the urine.
Too high or too low acidity
Healthy is a slightly acidic urine with a pH of 6. If the pH is lower than 5.5, the urine containstoo much acid.People with acid urine often developuric acid stones.
Urinary tract infections can cause theacidity of the urine to dropand the pH to rise. A pH above 7 favorsphosphate-containing kidney stones.
What influences the composition of the urine?
Which substances accumulate in which concentration in the urinedepends above all on the lifestyle,that is,
- how much you drink,
- how to eat,
- if you move regularly and
- whether you have certain pre-existing conditions such as chronicdiarrhea,goutordiabetes.
If a man drinks too littleliquid whileeating and drinking , hiskidneyscan produce only little urine. The water content of the urine decreases and the concentration of certain substances in the urine increases. Fluid loss throughsweating(eg in hot climates) ordiarrhea(watery stools) also increases the risk of kidney stones.
If you eat a lot of salt, more calcium and less citrate gets into the urine. Therefore, ahigh-salt diet increasesthe risk of calcium-containing kidney stones. Of course, these can also occur if youingesttoo large amounts ofcalcium-rich foods. These include milk, cheese and other dairy products.
A permanentlytoprotein-richdiet(lots of meat and sausage products, especially organ meats) leads to an oversupply of certain substances in the blood (known. Purines),which breaks down the body to uric acidand thus eliminated in the urine. If the level of uric acid in the urine rises above a certain level, uric acid residues can form.
High levels of calcium and phosphatein the blood can sometimes be attributed toparathyroid hyperfunction(hyperparathyroidism).
Anexcess of oxalic acidis sometimes the result of primary hyperoxaluria, a congenital enzyme disorder. The oxalic acid content in urine may also increase due to inflammatory bowel disease such asulcerative colitis(chronic colitis ) orCrohn’s disease. Then doctors speak of asecondary hyperoxaluria.
Ahigh concentration of uric acidin the urine is sometimes related todiabetes. Why, is not clear yet.
lack of exercise
People who move little often have an increased risk of kidney stones. If, for example, you arebedriddenfor a long time because of a serious illness, the body not only removes muscle tissue but alsocalciumfrom the bones.As a result, the concentration of calcium in the urine increases and kidney stones can form.
Kidney stones: diagnosis
If the patientcomplains of labor-like pain in the flanks, the doctor will consider kidney stones as a possible cause. To be able to make a diagnosis, he must first look at the kidneys. For this he can make anultrasound examination. If the results are ambiguous, he may additionally takeCT imagesof the kidney.
In addition, the doctor examines thepatient’s urine . For example, he can determinewhether the patient has an infectionor whether his calcium or uric acid levels are elevated.
Kidney stones: treatment
Small kidney stones with a diameter of 5 millimetersusually separate the patients within one month by themselves.Therapy is then not necessary. Sometimes, however, it causes pain when a kidney stone passes through the ureter (so-called acute ureteral colic). In this case, the doctor may prescribe anti-inflammatoryanalgesics such asdiclofenac.
If the stones aremore than a centimeter in sizeor cause severe discomfort, they should beremoved. This is especially advisable if:
- the patient has severe pain despite medication,
- the patient is also suffering from a urinary tract infection with fever and / or
- a kidney stone completely blocks the urinary tract.
This is how kidney stones are removed
Only uric acid stonescan sometimesbedissolvedby medication. The patient should then drink a lot, so that the kidneys form more urine, in which the uric acid can dissolve.
Other types of kidney stones can not be eliminated medically. To remove them, the doctor may either smash them or surgically remove them.
How can kidney stones be smashed?
To smash kidney stones,no surgery is needed. The doctor can smash kidney stones from the outside with the aid of so-calledextracorporeal shockwave lithotripsy (ESWL). To do this, he applies a probe to the skin, which sends sound waves through the skin to the kidney. The sound waves shatter the kidney stones into small pieces. These then excrete the kidneys by itself with the urine.
Duringpregnancyor untreated urinary tract infection, this therapy should not be used.
When is an operation necessary?
For kidney stoneswith a diameter of 2 centimeters or more,a shock wave treatment is not enough. The resulting fragments would still be too large to be excreted by the kidneys.
Large kidney stones usually need to be removed. However, an open operation is rarely used today. As a rule, doctors use the followingendoscopic procedures:
- Ureterorenoscopy (URS):The doctor introduces an endoscope and fine instrumentsthrough the urethra into the ureter.The doctorusesa laser to crush the kidney stone. Then he removes the fragments with a stone basket. If the urinary tract is inflamed, this method is not recommended.
- Percutaneous nephrolitholapaxy (PCNL): This procedure is performed under general anesthesia and is performed in the hospital. The doctorputs a small skin incision.Through the opening, he can insert the endoscope and surgical instruments directly into the renal pelvis or into the cavities of the kidney. Also, this treatment is not suitable during pregnancy and an untreated urinary tract infection.
Kidney stones: course
About85 percent of the smaller urinary stones areeliminated by the body itself. This usually happens within a month. Almost half of those affected do not develop kidney stones afterwards.
It usually makes sense to remove larger kidney stones that the body does not excrete by itself. This is absolutely necessary if the stonesclose the urinary tract. Because then there is arisk thatbacteriaimmigrateandcause infections of the urinary tractandkidneys.
Can you prevent kidney stones?
More than half of the patientsrepeatedlydevelop kidney stones. However, this can often be prevented with certain measures.
Kidney stones are formed when the urine contains so much of certain substances that they do not dissolve anymore. By drinking a lot (at least 2.5 liters of unsweetened liquid daily), you can dilute the urine and thus reduce the risk of kidney stones.
Soft drinks such as cola, however, are not recommended because they contain phosphoric acid (usually referred to as additive E338). Physicians suggest that phosphoric acid favors the formation of kidney stones.
In addition, one can specifically prevent individual types of kidney stones. Because some of the stone-forming substances are found in different foods, it is possible to lower their urinary concentration through acontrolleddiet:
- Those who haveoxalate stonesorcalcium oxalate stonesshould avoid oxalate foods such as spinach, rhubarb, beetroot, green and black tea, and chocolate and cocoa.However , people should not give upcalciumwith these types of stones, since too little calcium in the diet causes more oxalate to enter the urine.
- Forcalcium oxalate stones, it is also recommended to eatlow salt and low animal protein.
- In combination with gout and diabetes,uric acid stonesare common . Uric acid is produced by the breakdown of so-called purines, which are contained in animal offal (liver, kidneys, heart, tongue), meat and sausages, oil sardines and legumes.Maybe a low-purine diet helps toprevent uric acid stones. So far there is no scientific evidence for it.
Patients at increased risk for certain types of kidney stones may prescribe medication to the doctor:
- Calcium citrateis suitable for the prevention of kidney stones of calcium, uric acid and cystine. It reduces the acidity of the urine. The less acidic the urine, the more salts can dissolve in it.
- Allopurinollowers the uric acid level in the urine and thus counteracts uric acid stones. Studies have shown that it can also protect against calcium stones.
- Thiazide diureticsreduce the risk of calcium oxalate stones and calcium phosphate stones by causing less calcium to get from the blood into the urine.
Get real time update about this post categories directly on your device, subscribe now.