How do kidney stones form?

(See a visual timeline of kidney stone formation below)

Kidney stones are formed from substances known as soluble salts. Calcium oxalate-the most common type of kidney stone, is a soluble salt. It can exist in a dissolved form or in a solid, crystalline form.

When the concentration of a soluble salt in solution is high enough, it will begin forming into solid crystals, in a process known as precipitation. An example of a common soluble salt is sodium chloride in seawater. When seawater is allowed to stand and evaporate, the previously dissolved sodium chloride precipitates out of solution in the form of sea-salt.

Urine contains many chemical elements that can also combine to form soluble salts. These chemicals normally remain in a dissolved form in urine. Surprisingly, the concentrations of these salts in urine are usually much higher than what could remain dissolved in pure water. This unusual situation can occur because of the presence of inhibitors in urine that make it more difficult for soluble salt crystals to develop.

Some kidney stone inhibitors are substances from our diet, such as citrate, while others inhibitors are proteins manufactured by our bodies to help prevent the development of stones. Two examples of inhibitor proteins made by our bodies include Tamm-Horsfall protein and nephrocalcin.

Kidney stones initially form in a process known as nucleation when the factors encouraging salt crystals to develop outweigh the factors inhibiting salt crystals to develop. These crystals will continue to get larger over time and result in a detectable kidney stone if the conditions in urine remain favorable for stone formation.

Other important factors that affect the development of kidney stones include the amount of urine a person makes, with lower volumes leading to more concentrated urine, and the presence of slowed drainage, which can make it easier for crystals to gather and combine. The presence of a binding site can also make it easier for stones to start forming by acting as an “anchor” for crystals to develop on. A natural binding site is thought to be the small calcifications that can develop in kidney tissue known as “Randall’s plaques”.

A visual timeline of kidney stone formation

Click on images to enlarge them.


Image of precursor of kidney stone formation


Early development of a kidney stone



Growth of a kidney stone

Detachment and start of a kidney stone episode


43 Responses to How do kidney stones form?

  1. JoAnne says:

    To get rid of stones without lithotripsy, take a gallon of water, put in 1/2 cup of Real Lemon and drink it (for as long as it takes, I guess.) Lemonade is not quite as good because it has sugar in it. This concoction tastes terrible, but it works.

  2. santosh luitel says:

    is it possible to form 8.6 mm stone to a 18 month old child? if yes how to remove it ? is it possible to operate for such young child?

  3. povera says:

    I had a 30mm uric acid stone removed in April 2015 by pcnl . I had pain. In left side and frequent barring from march 2014. Doctors did not give me any results that I had a stone till Feb 2015. Why would I f orm such a large stone? How long would it take to form a stone so large stone o large? First 2 doctors I saw were not competent re diagnosing my

  4. I am a bladder cancer patient and lost my bladder Nov.3,2015. I have reassignment of my lower intestines formed and have a stoma to expell my urine . I wear a bag . I change it every couple days . I have been experiencing stones on my bag . Last night was one . I got it out of the bag and actually looked at it . I also had one the month before . I saved that one also .Both stones are almost identical in size and shape .Both look like a corn kernel , and just about the same size as a kernel . Both have a darker flatter side that looks like it was attached at some point . But also both seem to have metal wire Incorporated . But my belief is it might be a clip / staple from my reconstruction surgery . Both stones are whitish in color and darker grey on the flatter side . The white side also looks like sparkles are incorporated throughout. At this point it seems to me they are forming at a rate of one per month . Oh before I actually forget . Before my bladder removal my left kidney was in failure an a stent was in placement and I had a bag to catch the urine . I suffered my whole growing up with painful UTI’s . At 25 the UTI’s stopped until I was in my later 40’s . At 47 after leaving work I passed out and that day started my cancer journey . I had chemo almost one year. And still lost my bladder. I now have a rumor that showed up on a test just before this last Christmas . About August as far as I can remember . Anyway sorry about spilling my guts on this page . But alot of my friends are dying lately and it scares the crap out of me . Thinking I could be next . But I fought to stay alive ,and almost check out twice . I want to live and enjoy my life even with my stoma , which I hated at first but have come to except fully . It did save my life . And for that I’m greatful for it . But now my life is altered and different and I am learn my new setup of my intestines. And need to make sure to take the best care of them . It is a learning process but I can do it . I am strong willed and made it this far hence all the medical appointments , hospital stays , doctors appointments , and so on . Anyone willing to chat me about bladder cancer , kidney disease please do so . @ . Or message me on Facebook @ Libet DiChiara Sparks . Just send me a message as I don’t accept friend requests at allunless I actually know the person . Just say you seen this post I made . Thanks everyone for reading my post here . And good luck to everyone.

  5. Mas Mason says:

    I had a stint put in Thur and the nurse said I could play Golf in day that not true cause I
    have to pee ever 15 min if I walking round and the pain start at kindey and go to end of penis this is the first one that I could not pass have had 3 more that I passed don’t want no more that they have to put a stint in I can handle the one you pass /

    • Robert Hill says:

      I’ve had a stent in place for 12 days now. As long as I do nothing and don’t move, I can avoid peeing for an hour and a half to tow hours. When I stand up, I’d better be headed for the bathroom. I’m generally an active person at the age of 55, and the constant need to pee is driving me nuts. Can’t ride my motorcycle, can’t ride my bicycles. Went swimming today, and while at the pool 30 minutes had to pee three times.

      It’s known as “over-active bladder”, and it occurs because when you are active, the curl in the stent that is in your bladder, hits on the inside surface of the bladder, causing stimulation and the need to pee.

      I thought that it would go away over time. WRONG! It’s no better after 12 days than it was after two days. And the constant need to pee keeps me from enjoying sex. The erection fades away, and once flaccid I have to pee big time. It’s infuriating.

  6. William coley says:

    I am a kidney stone factory, currently I had 3 stones removed from some tube in my kidney because one was stuck a a couple lined up behind it. Now a stint is placed. Plus 3 more in my right kidney and 3 more in my left kidney, all waiting for stint to be removed.
    Without me having to read so many articles please recommend a strategy for me to kill these little boogers.

  7. Prince says:


    I have had some checkups and got to know that there’s some blood in my urine… doctor said it can be stone… what should i need to do … please suggest

    • Brett Bennett says:

      Drink a lot of water. With my stones, I always urinated blood before any pain hit. I’ve had two so far (20 years old) yet my mom has had over a 100 and no blood in urine ?.. But both times blood came before the pain. I never passed mine naturally.. I had to get surgery for the two and both were 4mm. But that’s me, and I have contricted vains in my family ( which apparently effects the urged dilation size), you should be fine though. Drink water, lemonade, and even beer ( be off pain meds for atleast 8-12 hours. Good luck! Avoiding surgery is the best option, so push fluids!!

      • Brett Bennett says:

        **Ureter dilation size**, and **constricted vains**, sorry for the grammar, I didn’t read over my post before I posted it.

      • Titus says:

        Are you sure that beer can cure kidney stone? B’cos i too have it in my ureter tube and i wnt treatment with surgery/operation

      • John gordon says:

        With kidney stones you want to avoid alcohol soda and sugar so lemonade isn’t good water and lemon will help. but no sugar alcohol or soda these things can lead to kidney stones

  8. JAMES says:

    Calcium Oxalate is not soluble in water, which is why the precipitate does not dissolve again when your kidneys are hydrated again.

  9. Hussein says:

    I had kidney stones fir 4 years now ,been to hospital many times , in fact get sick going to hospital as my kidney firm stones as shirt as 3 months , do nit know how to stop that.any help

  10. tapan barman says:

    I was just fit &cool ,I was reading newspaper, suddenly I felt severe pain when doc suggested to get a report of ultrasound .Their I came to know I have one stone in kidney (4.1) and in gallbladder multiple stones(5.0-11.5).I was stunned because I usually go to gym, I never felt so . No what I sued do?????

    • Robert Hill says:

      Whether you’re fit or not has nothing to do with stones. I’m fit as well, work out just about every day. I’m 55 and my urologist describes me as a Well Developed male. Yet I get stones frequently. I usually pass them with no complications, and have a collection of the damn things. Yet I have a 9mm plugging up my right side, that may kill my kidney. My urologist is unsure at this time. He’s going to get the stone with a laser, place a stent, and allow time to see if the kidney recovers, or not. Should know by this time next month.

  11. lee says:

    I didn’t know I had kidney stone until recently, the pain was terrible. But as soon as i found out that I had kidney stone, I started drinking a lot of water, cranberry juice and coconut water.

    these substances helps the stone to move especially when it is between the kidney and bladder (always keep drinking fluids to the tube would be open for the stone to move). I also stopped eating greasy foods and anything consisted of oil because it aggravates the stone and in a week’s time I was able to pass out my stone – it was small.

    So now I drink a lot of fluids and monitor my eating habits, there is a possibility of getting another, since my father and grand mother had kidney stone. I’m trying to stay positive and keep with this new plan of mine.

  12. jerry says:

    I had a 4cm stone(which you can see in xrays on my youtube channel libertyforamericanow)removed in 2013.took it out with tube thru back over a few surgeries.
    Had my last one removed in sep 2013.was 8mm stuck in uretor.removed thru penis.
    went 1 1/2 years no probs.
    untill last night.another 8mm in uretor.removed thru penis.
    Dont let surgery scare you.its nothing.

  13. divs says:

    Hi everyone, after having first stone I did a little research and got to know that eating more animal protein overloads kidneys and may lead to kidney stone even if drinking lot of water. potassium magnesium citrate pills can be taken with lot of warm water for few weeks to dissolve these stone and can help flush out this nagging stones.
    I have left taking any supplement of protein or vitamins now and now shifted towards diet suitable for kidney health like barley in place of wheat and eating horse gram twice a week which are considered to melt away stones. now I don’t stress out my body with too much exercise so I don’t require more protein supplements. only moderate exercise. turned towards natural ways to get nutritious diet. let’s see if it helps me. please share your experiences.

  14. Glen says:

    I normally drink a lot of tap water ( about 8 glasses a day) but I went on a 17 day trip to Russia where I had to get bottle water and so I was drinking very little (about 3 or less a day). I was also trying to stop from getting a cold tor a few days before I left and the first week so I was taking A LOT of vitamin C, B & Zinc and was eating a lot of chocolate…. A week after I got back I got my first kidney stone 2mm. Does anyone know could these facts be how I got this kidney stone??? Do they form that fast???
    Thank you,

    • Joe says:

      I was in Russia recently and drank less water also. I had eaten chocolate and nuts between meals while there. I was also taking zinc also before my trip. I passed a stone as soon as I got home and passed four more stones two days later at the hospital. I believe the long flight dislodged the stones I’m done with nuts and will cut back on chocolate to small amounts on special occasions. I have to see a urologist soon and hope to prevent future attacks.

    • divs says:

      I had same problem with 3.8 mm stone. I started taking a multi vitamin tab which contains a large dose of every vitamin. after taking this tab I felt less thirsty so I didn’t drink enough water only 3 glass of water a day. with in 5 days from starting this medicine and less water consumption I had this stone.
      while science says it take at least few months. confused…

  15. chandu says:

    thank u for giving information

  16. sophia archer says:

    I had a UTI back in Nov ’13 and continued to feel milaise. PCP SENT me to urologist and they took tests, CT and ultrasound. Then I had a cystoscopy. Kept find blood in urine, but could not pin point nothing.this was end of May.beginning I my of July, find myself in ER, killed in pain…come to find kidney stones in both kidneys, multiples in the right, largest being 8mms and the other in my left is just over 1 cm. I now have stents. Good times…not bad at first, but seems be less accommodating to my body than when we first meant. Can’t wait for removal of stones,and then f I’ll nail departure of stents!

    • Concetta says:

      Sophia, I know your post is old, but was wondering this: did the dr not see the kidney stones when you had the ct scan? I had microscopic blood in urine, had a cat scan and cystoscopy and dr said everything was fine. Now, two months later I’m in a lot of pain and peeing blood. I’m thinking its a kidney stone–but shouldn’t that have been discovered thru the scan and scope?!?

  17. Andrew says:

    I had a kidney stone back in 2008 (my first one) at age 23. I enjoy working out and was on a high protein diet, but i drank close to a gallon of water a day. Fast forward to 2014 and I am starting to notice lower back pain. its very light and i dont notice it very much, but i recall from my last one it starting out that way. I believe i am doing enough to prevent them by drinking a lot of water. I still stay very active and maintain a high protein diet, but I still drink a TON of water and don’t consume an abundance of sodium

    Am I in that wheelhouse of a recurring stone due to my bodies composition, or is high protein diet still the the reason my stone(s) may be forming. I do eat a lot of almonds and other nuts, as well as eat spinach, but i still drink a lot of water. My first experience I had two at once and my concern is that I will develop another one if I don’t change my diet.

    Should I discuss with my Dr. if I am prone to continuous stones? Or, is it just my diet that is the culprit?

    • Marcus Braga says:

      Hey, im in the same exact boat!!!! My first was at age of 23 in 09, now last week I had my second. I was wondering if you could share info on the diet part. I do eat alot of protein. Can u recomend anything to help dissolve and avoid them? Thank you so much!

  18. Sheryl Ferguson says:

    The worse part is having to wait so long to have them removed!

  19. Barbara says:

    I just had a kidney stone attack 6 days ago. My back had been hurting increasingly over 2 weeks & then at 3am that morning I woke up in horrible pain with nausea & vomiting. There’s an 8mm just outside the kidney & another 8mm about to drop out of the kidney. They placed a stent & scheduled surgery for one month away. Today the opposite side of my back is starting to hurt. I do not know if the CT was of both sides but think not since they confirmed about 100 times that it was my left side. Would that be improbable & weird to get stones in both kidneys at the same time. …the first time??

    • Sheryl Ferguson says:

      I had pain on both sides of my back and abdomen, but had 2 stones – one in the left kidney and one just outside the left kidney.

    • Suzanne Midson says:

      Yes….I have had several stones over a number of years. Fortunately for me I recognised the symptoms and contacted my GP for a referral
      to get a CT scan done that day. I also contacted my urologist for an appointment the same day. After the CT scan was done , I made my way to see the urologist. Whilst sitting in his reception area my GP phoned me and told me to get to hospital asap. I had a 6mm stone on either side of my kidneys and needed surgery immediately. He performed a cystoscopy procedure .
      I have just had my annual check up and have been told I have 10 stones in my left kidney and 4 in my right. I am drinking more water and have added fresh lemon juice to each glass. Hopefully this will slow down the growth of the stone. Good luck with your stones

  20. Santosh Sushil says:

    A good and useful site.

  21. stewart mckenzie says:

    i get stones atleast once a year it starts with kidney pain and when i go to the toilet to wee the wee is so red from blood does it mean the stone is moving down and causing damage to the kidney ?

    • sulleh says:

      yes, very, check it out with a doctor.

      • Sheryl Ferguson says:

        I have blood in my urine with a bladder infection – without a kidney stone, so I don’t necessarily think it means your kidney is being damaged. However, if you are not treated for your stone, it can cause damage.

        • Pathology student says:

          My renal pathologist professor told us that if you ever see blood in your urine, always, always get it checked out! It could easily escalate into something more serious.

  22. Shehab says:

    This information is very helpful. Putting it in layman terms makes it so much easier for those of us who are not familiar with medical terms. Is there any tests to comply with on a monthly basis to ensure one does not suffer from stones ?

  23. Michelle says:

    I have been trying to manage the pain from a large kidney stone for more than 7 mos now. No insurance to do anything about it. Meanwhile I have been trying to learn about them and why and how and where they are in my kidney. I am haveing the sound wave surgery in a week. Although I have learned a lot about the kidneys and their functions, I have learned very little about the kidney stones and how they are formed. This article has taught me more than anything I have read so far. I now have a much better idea of how this happened to me and what I can do to help prevent it. The best thing is that I understand what is happening inside of me. I have adreanal mass inside my kidney, which I was like Huhhhh? Now I understand from this article that it is called “Randall’s Plaque” and because of it this is how my kidney grew such a large stone. Totally make since now. Thank you for an article so clearly written in layman’s terms. Not understanding what is happening to you is very stressful. Again thank you for helping me to understand and feel a whole lot better.

  24. bea russo says:

    How long does it take for a kidney stone to form

    • says:

      Here’s the answer from our frequently asked questions page:

      It appears that stones can form in as short a period of time as three months. This is based on research of soldiers deploying to Kuwait and Iraq where the mean time to development of a symptomatic stone was 93 days in the hot desert environment. (Evans and Costabile, J Urol, 2005)

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