(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.
A good and useful site.
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 ?
yes, very, check it out with a doctor.
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 ?
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.
How long does it take for a kidney stone to form
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)