A kidney stone is a crystal that is being formed in the urinary tract. Kidney stones usually range in size from a grain of sand to a chestnut. Smaller stones are flushed away when they get loose and then lead to pain and usually some blood in the urine. Large stones often show no symptoms, but can be a hiding place for bacteria.
Under certain circumstances, urine may contain a surplus of salts, which are deposited in the form of crystals. Those crystals can sometimes be large enough to create blockages or cause other problems in the urinary tract. These are called kidney stones, ureteral stones or bladder stones, depending on where the stone is found. Kidney stones occur frequently in the renal chambers and renal pelvis. The cause of kidney stones is complex. Diet and living habits affect the development of kidney stones. Moreover, there are (congenital) diseases that increase the risk of kidney stones.
The development of kidney stones can be caused by:
- Insufficient urine production. This allows the urine to be too concentrated and the salts are forming crystals, that can accumulate. Insufficient urine production can be a result of drinking too little and/or more moisture loss from the body due to, for example, diarrhea or extensive sweating.
- Too much secretion of salts in the urine. This may be caused by excessive intake of certain substances via food. Particularly, too much protein, such as in meat and (common) salt, may be the cause.
- The composition of the urine. There can be too much secretion of salts, but also too little of substances which just counteract the development of stones.
- A changed acidity of the urine. This makes the salts less soluble.
- A urinary tract infection
(bladder infection). Some bacteria can convert substances and thus contribute to stone development.
Kidney stones don’t always cause symptoms. The pain arises only when a kidney stone gets stuck. It often starts with a vague, inconspicious pain in the flanks of the lower back. Gradually, the pain gets sharper and comes in increasingly violent attacks, usually at the side of the abdomen. The pain often radiates to the groin, upper leg or genitals. During an attack, there is often extreme urge to move. Patients are restless and walk around. Some people literally crawl on the ground in pain. Sometimes, there is simultaneously fever due to a secondary urinary tract infection. Other possible symptoms are nausea, vomiting, sweating, blood in the urine and having to pee more frequently.
The symptoms are often, together with the detection of blood in the urine, sufficient to make the diagnosis. However, there are more diseases which present themselves in a similar way. If the symptoms and the blood in the urine don’t disappear during about a week, an ultrasound of the kidneys is often made in order to see if the stone is still present or another reason can be found for the symptoms.
Usually, a drug is given for the severe pain. This is often an anti-inflammatory painkiller (NSAID), such as diclofenac. After about a week, the symptoms should be over and there should be no blood in the urine anymore. Kidney stones which cannot be discharged spontaneously, can be removed in several ways:
- By comminution with a lithotripter.
- By removing the stone with a ‘gripper’ from the kidney or ureter via the ureter and the bladder.
- By surgery (rarely necessary).
- By dissolving them.
During a kidney stone attack, the patient should not drink too much because this can trigger a new attack.
More than half of people who have been treated for kidney stones, will often suffer from kidney stones again within seven years. Kidney stones can cause permanent damage to the kidneys. If both kidneys are involved, there is danger for chronic renal impairment (kidney failure).
- Drink sufficiently fluids each day.
- Drink before going to sleep, in order to let the production of urine continue at night.
- Take more fluid in hot weather, also if you are moving a lot and have an elevated body temperature.
- Don’t use gastric acid binders, which contain calcium.
- A patient may get the advice from the general practitioner to use less dairy products.
- Don’t eat rhubarb, spinach or asparagus in order to prevent stones made up of salts of oxalic acid.