Last updated date: 11-Mar-2024

Medically Reviewed By

Interview with

Dr. Sung Yul Park

Medically reviewed by

Dr. Lavrinenko Oleg

Originally Written in English

Urinary Stone Disease Facts - Viewpoints from Expert Doctors

    Our kidneys are amazing organs. They are the bean-shaped organs on either side of the spine. They work silently, filter the blood, remove waste, keep the body’s fluid balance, and keep normal levels of electrolytes without you noticing anything. 

    All of the blood passes through them several times a day. When the blood goes into them, waste is removed, minerals and water levels are adjusted, and salts balance is achieved. 

    Each human kidney has around one million tiny filters called nephrons. Surprisingly, we can only have 10% of our kidneys working, and we wouldn't feel any difference at all, no symptoms and no problems. 


    But what happens if there is a disturbance of the minerals and salts concentrations in the urine? What happens if they crystallize inside the kidney? 

    This is when the kidney forms stones; a condition that is known as renal calculi, nephrolithiasis or urolithiasis. 

    Kidney stones can affect any part of the urinary tract starting from the kidney down to the urinary bladder. It originally forms where the urine becomes concentrated, and minerals and salts stick together and crystallize forming hard deposits. Then, stones can move from one place to another according to their size. 

    You might have heard about how hard it is to pass a urinary stone and how painful it could be. However, a urinary stone will be silent with no symptoms until it moves within the kidney or passes into the ureters. If the stones become lodged in the ureter, it will block the flow of the urine from the kidney to the bladder, and it will cause back pressure on the kidneys. Consequently, the kidney will be swollen, and the ureters will spasm resulting in severe pain in the lower back where the kidneys are located, the pain is known as the renal colic. 


    At this point, patients experience the following symptoms and signs:

    • Severe sharp pain in the areas where the kidneys are located, in the side and back below the ribs. 
    • Pain that radiates to the lower abdomen and groin.
    • Burning sensation while urinating. 
    • Painful urination. 
    • An intense need to urinate. 
    • Nausea. 
    • Vomiting. 
    • For men, pain at the tip of the penis. 
    • Blood in the urine. Sometimes there is very little blood that can't be seen by the naked eye. 
    • Cloudy urine with a bad odor. 
    • Difficulty passing urine. 
    • Fever and chills, if there is a superadded infection. 

    The pain resulting from a urinary stone can be different in location or intensity from time to time as it moves around within the kidney. 


    So, what are these kidney stones made of? 

    Kidney stones come in different types and compositions. The treatment of a kidney stone or the prevention of forming a new one depends on knowing what type of stone it is. 

    There are four types of kidney stones. 

    The most common type that represents 80% of all stones is calcium stones. Calcium stones are subdivided into two other types: calcium oxalate and calcium phosphate. Calcium oxalate is, by far, the most common type of calcium stones. People who have too much calcium in their urine are at a higher risk of forming calcium stones. And even if there are normal amounts of calcium, these stones can form for different reasons. 

    The second type of stones is uric acid stones. They represent 5-10% of kidney stones. But what is uric acid anyway? Uric acid is a waste product that is produced from some chemical changes in the body. The harmful character of uric acid is that it doesn’t dissolve well in acidic urine and, hence, form uric acid stones. 

    The third type of stones is struvite or infection stones which represent 10% of all kidney stones. They are related to chronic urinary tract infection. Some infections make the urine more acidic while some others make the urine more alkaline. Magnesium ammonium phosphate (struvite) stones form in alkaline urine and they grow very fast becoming very large with branches.

    People with chronic urinary tract infections or improper emptying of the bladder due to neurologic disorders are at a higher risk of forming struvite stones. 

    The fourth and last type of kidney stones is cystine stones with the least percentage of 1%. Cystine is one of the building amino acids of proteins. Inherited metabolic disorders with too much cystine in the urine are one of the causes of cystine stones. 


    Kidney stones have no single definite cause, they usually form due to a mixture of risk factors. As a general rule, stones form when there is more crystalline-forming substance than fluids that the urine can dilute. 


    Let’s talk about some of these risk factors and causes

    • Low urine volume. It is majorly due to low fluid intake or high fluid loss. It results from dehydration, hard exercise, living in a hot place, or not drinking enough water. When the volume is low, urine becomes more concentrated and darker, which means that there isn’t enough fluid to keep the salts and minerals dissolved. That’s why adults who form stones are advised to drink around 2.5 litres of water every day. 
    • Certain diets. Diets can affect the probability of stone formation in the kidney. For instance, calcium stones form due to high calcium amounts in the urine. But does that mean we have to decrease calcium intake in our diets? In fact, doctors found that if we decrease the calcium in the diet, that wouldn’t stop calcium stones from forming. On the contrary, that would be harmful to the teeth and bones and calcium stones will still be forming. Too much salt in the diet is a risk factor for calcium stones. Too much salt will keep the calcium from being reabsorbed from the urine to the blood. 
    • Bowel conditions. Certain bowel conditions that cause diarrhoea or certain surgeries can increase the risk of forming calcium oxalate kidney stones. 
    • Obesity. It is considered a risk factor because overweight and obesity may change the acidity of the urine and give a favourable medium for certain kidney stones to form. 
    • Medical conditions. Some medical conditions can lead to kidney stones formation such as parathyroid gland enlargement which leads to abnormal calcium levels in the blood and urine and stone formation. Another condition is distal renal tubular acidosis in which there is a rise of acid levels in the body and a high risk of calcium phosphate stones formation. 
    • Medications. Some medications, calcium supplementation, and vitamin C supplements can increase the risk of kidney stones. 
    • Family history. The chance of having a kidney stone is much higher for a patient if he has a parent or sibling who had kidney stones before. 

    Those are the reasons why some people get stones and others don’t. 


    Now we will move to a new part of our video. We will talk about how doctors can diagnose kidney stones. 

    If your doctor suspects from the patient's history that he has kidney stones, he or she will conduct a physical examination to confirm or rule out this suspicion. 

    After finishing the physical examination, some investigations will be required to confirm the diagnosis, know the location of the stone and study its composition. 

    These investigations include: 

    • Blood test. It can reveal the level of certain minerals and salts in the blood such as calcium and uric acid. It can also help monitor the condition of the kidneys during treatment and check for other medical conditions. 
    • Urine test. The doctor might ask for a 24-hour urine collection to detect any abnormality in the composition of the urine. It may reveal the presence of too many stone-forming substances or too few stone-preventing materials. Sometimes your doctor will ask you to perform this test over two consecutive days. 
    • Imaging. This is a very useful investigation. Options of imaging are many and each one has its benefits and limitations. For instance, ultrasound is a non-invasive, quick and easy imaging test. X-rays are also used but less frequently because they can miss small kidney stones. There is also a CT scan that may reveal even the tiny stones. 
    • Analyzing the stone when passed. If the doctor thinks that the stone is going to pass, he or she will ask the patient to urinate through a strainer to catch this stone. Then it will be analyzed in the lab to discover its composition and the makeup of your kidney stones. This is extremely helpful because, according to the results, the doctor will be able to identify the cause of the stones and formulate a treatment plan to prevent further formation of stones. 

    Sometimes there is what’s called a “silent kidney stone”, and it is usually discovered on regular checkups while performing X-rays. 


    As for the treatment of kidney stones, it varies according to the type of the stone and the cause behind it. 

    Small stones are usually treated by drinking plenty of fluids, pain relievers, and medical therapy. 

    Larger stones, however, have different treatment options. 


    Our role today is to answer most of your questions regarding Urinary Stone Disease. Today we have Dr. Park, who is a leading doctor at Hanyang University Hospital in Seoul. He is going to discuss Urinary Stone Disease from an experienced medical point of view.



    Dr. Sung Yul Park Interview


    Professor, can you tell us a bit about what urinary stone disease is?

    In our bodies, we can develop stones in various places. There are two types of stones that people are familiar with. One is gallstones that are in the gallbladder. You’ve heard of it right? Urine is produced from the kidneys, descends through the ureter, and is collected in the bladder, and then exits. During this whole process, whatever urine-related stone is produced, we call it a urinary stone.


    How about the symptoms of urinary stones, and maybe the treatments afterwards?

    For urinary stones, the treatment is not just one method. Like I mentioned before, if there are stones in the kidney, we call it kidney stones. If there are stones in the ureter, we call it ureter stones and if there are stones in the bladder, we call it bladder stones. So according to the location and size, there are many ways for treatment.

    When there are stones in the kidney, you have no symptoms at all. But because these urinary stones exist in the path of urine, symptoms arise when it interferes with the urine flow. So even if these stones are in the kidney, if it doesn’t interfere with the urine flowing down, there is no problem. However, if it blocks the way of the urine flow, just like a clogged sewer, it makes the urine flow upwards instead which causes pain. But the pain of urolithiasis is so severe, like that of labor pain, so the pain is in both the left and right sides of the back. On the back of the ribs, you have your kidneys - this is where it hurts. And that is the main symptom. If these stones come lower down and block the way of urine, even urinating can be impaired.

    Earlier, I said that hematuria can occur in bladder cancer. Urolithiasis can also cause hematuria, but characteristically, this one hurts. So, hematuria in bladder cancer is painless, but the biggest symptom of urolithiasis is pain, including in hematuria.


    Doctor, you talked about the types of urinary stones, can you tell us in more detail about the types?

    So many of us know that there’s a lot of calcium in stones. In fact, around 70% of what makes the stones is calcium. And calcium is the same ingredient as our bones. So just like our bones are very visible on x-rays, 70% of urinary stones are easily visible. But we eat a lot of meat and high-calorie foods. And a metabolite of protein produced by eating meat is called uric acid, which is also closely related to a disease called gout. And this uric acid does not show in x-rays so a CT scan should be done to check. So, the main ingredient is calcium, but it also contains other ingredients such as uric acid.


    Are there any examinations we can do to know if we have urinary stones or not?

    If you already have clear symptoms, in some cases, we can already assume just by looking at how the patient walks in pain. Usually, we do an X-ray as we can see 70% of the stones on the x-ray. But if it is hard to tell or if it is still unclear whether they are stones or not from the x-rays, a CT scan must be done. In CT scan, over 99% of stones can be diagnosed.

    As I said earlier, there are various ways of treating stones according to location and size. So, it’s not just a matter of whether you have stones or not, but we need to examine where it is exactly located, how big it is and what it’s surrounded by to treat it accordingly.


    In this case, what are the treatments used and after the treatment, is there any diets patients should follow?

    The most common treatment is to let it disappear on its own. Stones that are around 5mm, as small as sand, can disappear by itself if we drink lots of water. But even if the stones are out and the treatment is finished, the state of the body does not easily change. This change only comes from daily effort, and the main one is drinking plenty of water.

    An ingredient of urine turns into stone, just like salt is formed from sea water. So, whatever the case, we must drink plenty of water to dilute urine and also to help drain out small stones quickly. We always recommend drinking 2-3 liters of water a day which is actually a huge amount. It is good to always drink lots of water, but when drinking water to specifically drain out small stones, it is better to drink large amounts at once rather than little by little.

    On the internet, it is rumored that drinking beer can help drain out stones, but I’m not saying we should drink lots of alcohol. I’m saying drink lots of water at once to increase the amount of urine so that the stones can be drained out. So, when you have stones, that is the way to do it, but normally you should be drinking 2-3 liters of water a day.

    Another thing that makes it a good condition for stones to form is salt. Salt itself doesn’t create stones but consuming a lot of food that contains salt increases calcium excretion in the urine. And as calcium is the main ingredient of stones, the saltier food you eat, the easier it is for stones to form. As mentioned before, uric acid can also develop, and this is closely related to meat so if you have lots of stones, you need to cut down on meat. Also, oxalate contained in food such as nuts are known to have an effect of clustering stones, so it is said to cut down on food that contains such ingredients.

    There are also helpful ingredients like citrus fruit such as lemons or oranges. We call it citrate. Citrate is in citrus fruits like lemon or oranges and this is known to have such a strong and positive effect on preventing stones, that there is even a medicine made with this ingredient. So, if you normally drink orange juice or lemon juice, it can help prevent stones. And lastly, preventing obesity and exercising regularly can also help prevent stones.


    My last question, in the case of urinary stone disease, are males more likely to have it than females?

    This as well, men have it more often. It is twice as common. But there is a period when women start to have it similarly to men. This is after menopause. The female hormone, which only women have, is effective in preventing stones from occurring. So, this is why young women don’t usually have stones as they have female hormones that are superior to men. But women eventually reach menopause when they get older, and as you lose female hormones, the effect in preventing stones becomes ineffective.

    This is why women increasingly have stones as they get older. So normally drinking plenty of water is important but also strongly advised especially after menopause. But usually, men have it more often.


    Urine is produced from the kidneys, travels down through the ureter and collects in the bladder, then comes out. During this process, if stones are produced, we call them urinary stones.

    The main symptom of urinary stones is pain, very intense and characteristic, it may be accompanied by hematuria. You can also have urinary stones without any symptoms, and this is the case with kidney stones.

    70% of urinary stones are made up of calcium, visible on x-rays. The rest is uric acid that cannot be seen on x-rays, so a CT scan is needed to confirm the diagnosis.

    The most common treatment is to let the stone go by itself by drinking lots of water. There are also useful ingredients like citrates in citrus fruits such as lemons or oranges. It is also important to prevent obesity and exercise regularly.