Kidney stones (medical nephrolithiasis or urolithiasis) arise from salts that bind water-insoluble compounds. The resulting crystals can cause various diseases.
Depending on the location of the stones, one speaks of kidney stones or bladder stones. Kidney stones form in the kidney, bladder stones in the bladder. Kidney stones can also travel through the ureters into the bladder and from there into the urethra. Very small kidney stones are also called kidney grits.
Kidney stones consist of calcium oxalate uric acid (urate stones), calcium phosphate, magnesium ammonium phosphate (struvite or infection stones), cystine or xanthine. Mixed forms are also possible. The components of these crystals are usually dissolved in the urine. Above a certain concentration, however, they form water-insoluble compounds. These usually crystallize in the kidney pelvis or less often in the bladder. And from there the kidney stones sometimes wander through the urogenital tract.
Kidney stones and bladder stones can initially go unnoticed for a long time because they do not have to cause any symptoms. If, for example, they migrate from the kidney into the bladder and further into the urethra, they can get caught there.
Causes of Kidney Stones
The causes of kidney stones are very different. Heredity, urine composition, malformations in the kidney, too little exercise, metabolic diseases or even eating habits play a role. There are a number of different kidney stones.
Infectious stones arise for example as a result of repeated bacterial urinary tract infections. The bacteria in turn raise the pH of the urine (above 7), it becomes alkaline. Alkaline urine in turn promotes the formation of phosphate-containing stones.
Urate and uric acid stones: Acid urine (pH below 6) favors the formation of urate and uric acid stones. Urine often becomes acidic due to gout and foods containing purine (especially meat and sausage products and offal). These foods increase uric acid levels and urine pH drops. Strict fasting cures, cancer or chemotherapy can also increase uric acid levels and make the urine acidic; thus promoting the formation of uric acid stones.
Calcium oxalate stones are often nutritional. A milk-rich diet increases the calcium concentration in the urine. The level of oxalic acid in the urine increases when a lot of chocolate and cocoa products, spinach, beetroot or rhubarb are eaten. As a result, calcium oxalate stones often arise. These kidney stones are also favored by an overactive parathyroid gland.
Cystine stones form due to a genetic disturbance in the amino acid metabolism (cystinuria), which leads to the formation of cystine stones, especially in children.
Common causes of kidney stone formation:
- Calcium metabolism disorders
- Disorders of uric acid metabolism
- Insufficient fluid intake or loss of fluid (especially excessive sweating or diarrhea in chronic bowel diseases)
- Improper diet with too much protein, fat, calcium
- Chronic urinary tract infections
- Other diseases that restrict urine drainage and cause urinary congestion
- Genetic causes
- Hyperfunction of the parathyroid gland
- Cancer, chemotherapy
Symptoms of Kidney Stones
If the kidney stones are stuck in the ureters, at the bladder outlet or in the urethra, they suddenly cause violent cramp-like, wavy or stinging pain in the lumbar region (renal colic). The pain usually radiates to the unaffected side or into the lower abdomen. Sometimes they are accompanied by chills, nausea, vomiting, urination or blood in the urine. Small stones are often rinsed out. They usually cause a brief stabbing pain when urinating.
It becomes dangerous if a kidney stone is stuck in the ureter and prevents the urine from flowing out. The urine builds up in the kidneys and the kidney pelvis expands. This allows bacteria to migrate more easily into the kidneys and cause infections, for example acute kidney inflammation. A typical symptom is flank pain, in severe cases there is a fever and chills. If the bacteria get into the blood, there is a risk of life-threatening sepsis (blood poisoning).
Inflammation of the kidney through kidney stones
If the stones are too large for walking, they remain in the kidney and cause chronic kidney inflammation. Even such stones often cause little discomfort. Chronic renal pelvic inflammation, however, can lead to a shrinking kidney in the long run.
If you have the slightest suspicion of kidney stones or kidney inflammation, i.e. kidney pain or kidney colic, you should go to the doctor. This is especially true when there is a fever. You should have a general examination if the urine is dark or reddish due to blood.
What is the Course of the Disease?
The course of stone suffering is unpredictable. Stones that are smaller than two millimeters come off in about 80 percent of the cases without treatment. Even if the stone is excreted, an examination must be carried out by a doctor, since other urinary stones may have gone unnoticed. Half of those treated have urinary stones again.
Stones larger than an inch are rarely excreted without treatment. They can remain unnoticed in the kidney and grow into larger stones, which then take up a large part of the kidney pelvis, for example. The kidney is damaged in the long term. If both kidneys are damaged, the body is no longer detoxified and the patient has to go to the artificial kidney, the dialysis.
Most patients become stone-free within a few days under therapy, but in individual cases stone therapy can take weeks. The patient's personal well-being depends heavily on the course of the disease and the form of therapy.
Treatment of Kidney Stones
The therapy of kidney stones is primarily based on the position of the kidney stones.
Rice grain or pea-sized kidney stones are usually treated with a combination therapy. This includes analgesic, antispasmodic and flushing medication, warmth, exercise (especially bouncing and climbing stairs) and lots of fluids.
Drug dissolution of kidney stones (litholysis) is only possible with uric acid stones (urate stones) and cystine stones. Allopurinol, the active ingredient that lowers uric acid levels, is added and the urine is alkalized with alkali citrates or sodium bicarbonate (target pH 6.2 to 6.8). In addition, the patient has to change his diet to keep urine acid levels as low as possible. When these three methods are combined, uric acid or cystine stones dissolve.
Drug therapy for large kidney stones
Larger kidney stones that trigger renal colic often cause pain that is comparable in intensity to contractions. Pain relievers (such as oxycodone) are usually given to treat this pain. Treatment with non-steroidal anti-inflammatories such as diclofenac, the antispasmodic butylscopulamine and the pain relieving pyrazolone derivative metamizole is also common.
Smash kidney stones and kidney stone surgery
Small kidney stones can be shattered during an outpatient endoscopy or removed with a medical sling if they are convenient.
Larger stones can be crushed by means of acoustic pressure waves (shock wave treatment or extracorporeal shock wave lithotrypsy, ESWL for short). In some cases, surgery is necessary to remove kidney stones.
Smaller urinary stones are particularly likely to spontaneously come off without any further help from a doctor. The stones then often come off through increased drinking and exercise without the need for treatment. As long as there are no complaints, waiting under regular medical supervision is possible and promising. The time until the stone leaves increases with the size of the stone: on average around one, two or three weeks for stones with a diameter of two millimeters, three millimeters or four to six millimeters. Stones up to a size of four millimeters are classified as spontaneously removable. The passage of the stone can be promoted with medication. If there are signs of inflammation in addition to the kidney stones, targeted therapy with antibiotics and a review of the previous therapy should be carried out.
Treatment of Kidney Stones Colic
Pain control is paramount for patients with colic. Antispasmodic and analgesic drugs are prescribed. Pain therapy often leads not only to pain relief, but also to stone exhaustion through the relaxation of the ureter. This therapy is supported by the administration of fluids and lots of exercise.
In the case of very violent, long-lasting colic and / or inflammation with simultaneous urine build-up, a thin, internally hollow splint can be inserted into the kidney pelvis. To do this, the urologist uses a special device to go into the bladder through the urethra, insert a splint into the ureter and then remove the bladder mirror device.
After the end of treatment, the ureteral splint is removed by means of a new bladder examination. During these interventions, the ureter can be injured in rare cases; as a late consequence, narrowing of the ureter and urethra can occur.
Kidney Fistula Catheter
If it is not possible to insert a ureteral splint, or if it does not make sense in individual cases, a catheter can be inserted through the skin of the flank into the kidney under local anesthesia under ultrasound control. Doctors then speak of a kidney fistula catheter, the urine flows out into a bag until the final therapy. This procedure rarely causes bleeding or injuries to the kidney or other organs that require treatment.
When treatment is complete, the renal fistula catheter can be removed from the outside. The kidney fistula catheter is an initial measure and is not used for stone removal, so that further treatment for the actual stone removal must follow. A kidney fistula catheter can be life-saving if there is kidney inflammation.
Dissolution Treatment - Litholysis
The dissolution of stones by administration of medication, also called litholysis, is only possible with uric acid stones and small cystine stones. The principle is to change the pH of the urine so that the stones decrease in size and come off with the urine or dissolve completely. This can be done with the help of medication to be taken or by a local flushing.
The urine pH value for patients is typically 5. Doctors recommend a pH value of 7.0 to 7.2 for neutralizing urine. The following measures can serve this goal:
- Administration of potassium citrate or sodium bicarbonate to improve the solubility of uric acid
- Allopurinol to reduce uric acid levels in blood and urine
- Urine output increased to two liters per day
The urine pH value is checked with indicator paper, which is held in the urine (jet) several times a day. The color change on the test strip indicates the pH and the amount of medication is then adjusted accordingly. The therapy takes about six weeks. During this period most of the uric acid stones have dissolved.
But even after the stones have left, the urine pH should be kept in this range to prevent the stones from recurring. The drugs are well tolerated, but occasionally trigger mild abdominal discomfort and nausea.
The most commonly performed therapy today is shock wave treatment, also called extracorporeal shock wave lithotrypsy. It is usually used for stones in the upper and middle third of the ureter and in the kidney. The stones are shattered by weak acoustic shock waves.
After the treating physician has located the stone using X-rays or ultrasound, he adjusts the device so that the shock waves can destroy the stone without causing any appreciable damage to the surrounding tissue. The crushed stone particles then go off with the urine.
The treatment is usually done on an outpatient basis and without anesthesia, but with painkillers and sedatives. It lasts up to an hour.
Kidney stones that are smaller than two centimeters respond particularly well to shock waves. However, if the kidney stone is larger, multiple treatment appointments are often indicated. For every fifth patient, it is therefore necessary to repeat the shock wave treatment every few days. Thereafter, 90 percent of the patients are stone-free.
Occasionally there is bleeding into the skin, pain in the flank and bloody urine for a few days. Rarely, bruising around the kidney or fever develops. Injuries to other organs are very rare.
An ECG monitoring is necessary due to the possible triggering of cardiac arrhythmias. If stone debris is stuck in the ureter, it may be necessary to insert a ureteral splint or a kidney fistula catheter. For this reason, a ureteral splint is inserted into large stones before they are broken up.
The success with ureter stones is less than with kidney stones, because on the one hand the stone in the ureter lacks the space for shattering, and on the other hand the stones there are more difficult to locate. If stones are stuck in the ureter, they can be removed using a ureter mirror.
Stones that are difficult to locate and are therefore unsuitable for shock wave treatment can usually be removed using ureteroscopy, ureterorenoscopy. A special device is used to probe the ureter through the bladder under anesthesia or local anesthesia and remove the stone while viewing.
Slight ureter injuries from the device can occur in up to ten percent of patients, but usually heal by inserting a ureter splint without further treatment. Rarely, ureter narrowing can occur as a late consequence.
Percutaneous nephrolitholapaxy is mainly used for large kidney stones and when the ureters are blocked.
Under general anesthesia, the abdomen is punctured. The urologist can then create a thin access channel and insert a special optical instrument, the nephroscope, down to the kidney. After he has crushed the urinary stone in the kidney with a special working probe, the doctor can then remove the stone remnants with a forceps-like instrument.
After the procedure, a catheter is inserted through the canal into the renal pelvis, which secures the urine drain in a bag and can be removed after a few days.
The complication rate is very low. Injuries to the renal pelvis with scarring and bleeding are possible, which make blood transmission necessary in three percent of those treated. Every tenth person has a fever after the procedure. Injuries to other organs are very rare.
The recovery phase is four days to two weeks, depending on the size of the stone being treated. With this method, four out of five patients become stone-free. Smaller remaining stones can be crushed later using shock wave therapy.
Most stones can now be removed using shock wave treatment or percutaneous nephrolitholapaxy. The rate of open stone removal has dropped to about one percent. For large stones that fill the kidney pelvis, however, it remains an option.
Depending on the position of the stone, the cut can be made in the area of the flank or lower abdomen. The unchanged position of the stone is checked again directly before the operation. After opening the kidney pelvis or ureter, the stone can be crushed and removed with instruments.
A ureteral splint is often inserted during surgery to ensure urine output. The splint must be removed later during a bladder examination. After an incision, a recovery time of two to three weeks can be expected.
Possible complications include bleeding or - less often - injuries to other organs. The other complication rate is low if the surgeon has appropriate experience. As with any surgery, wound healing disorders, thrombosis, or infections can occur. As a late consequence, a narrow urethra can develop in the area of the operation site.
After Kidney Stone Removal: How Do I Prevent Kidney Stones?
After kidney stone surgery or kidney stone removal, it is important for the patient to know how to prevent kidney stones. It is particularly important to drink a lot, preferably two to three liters a day. Just before going to sleep, you should drink enough to prevent highly concentrated urine. Alcohol, coffee and tea should also only be consumed in moderation. In addition, nutrition plays a big and important role. Salt and fat should be reduced, the intake of animal protein restricted and foods rich in purine avoided. The purine-rich foods include offal and some types of fish. You should also take care to absorb enough calcium, as this can reduce the formation of the stones. This can prevent the formation of new kidney stones and prevent further kidney stone surgery.