This kidney stone overview integrates the seven articles about kidney stones one to another and offers a reading sequence for those who care.
I have taken the trope of a walking tour as a way of visiting places where we will not tarry long but that taken together tell a story larger and more interesting than any one place alone.
In simple words this introduction tells how protein matrix binds stone crystals into a kind of composite that is hard and can take many shapes. Being hard and large enough to obstruct the urinary system they cause pain and bleeding, and can foster infection. They tend to recur with an average interval of 2 – 4 years. Most importantly stones of any one person contain specific types of crystals and we prevent stones by preventing formation of those crystals. That makes analysis of stones central for prevention. Mere water can reduce recurrence. I show results from the one excellent trial. But treatment specific to stone crystals offers more potential for a long lasting cure.
What are the specific kidney stone crystals? How do they differ from one another? This long article catalogs them and gives quite a background into their physical chemistry and structures for those who want it. I once called this a primer, but gave up that title as obscure. Too bad. Primer can mean an introductory text book or, in this case article. And indeed it introduces what you need to know in order to understand the results of kidney stone analyses. Even more, as a stone former you are named by your stone crystals. How else? The problems you need solved for prevention arise from the problems posed by your kidney stone crystals. Many people read this article weekly to learn the basics of kidney stone disease.
We change all the time, and our stones change, too, from type to type. As they change, given that each type poses its own special problems, we need to know. Struvite may form because bacteria infect old calcium oxalate stones. Uric acid may add on over an older stone, or become the main kind of stone because urine pH falls – from age, increasing obesity, falling kidney function. Phosphate content may rise because of, perhaps, many shock wave lithotripsies. How will anyone know unless they analyse successive stones? But even I, who wrote the article, can falter after a few stones have gone by. I should not. No one should. If the crystals you make chang, treatments may need to change.
When you send a stone out to a laboratory to find out what crystals make it up you expect to get the answer: What crystals are in it, and the relative proportions of crystals when more than one is present. That answer may be true or not – just so. The technique is scientific, but science bounded by economic constraints so that answers are good but not as good as possible. Given enough time and money per stone one can know everything, exactly. But at the marketplace price, one gets reasonable enough answers most of the time. I am not so sure everyone will like this article because of its message: Be aware; analyse as many stones as possible to be sure you know what you are trying to prevent.
Since we are in Ireland, along the coast, I guess lunch can be anywhere on the grass. Here perhaps.
We have been touring the foundations of stone disease, some of its oldest parts. Any doctor who cares for patients with this disease will have known all about what we saw. Patients who form stones will want to know precisely what they are made of and how that fact was ascertained. There is a lot of science left to be done in this seemingly well studied realm.
This afternoon, we are going to look at something much less understood, and seemingly very important. What is it that glues the crystals together? Does the glue matter?
We will also study citrate as a molecule that specifically inhibits crystals from forming and growing.
The article was written for scientists but frankly anyone can read it.
The message is science in evolution.
Right now we are all in the dark. It is as though we have come upon a trove of writings in an unknown language. We do not know what is being said, and have no clue as to the purposes of what we see.
Stones are filled with proteins, perhaps many by random association. We think these proteins, which are present in urine, stabilize crystals, perhaps promote their formation or inhibit their growth, and possibly glue them together to make stones of clinical magnitude.
A link comes off of this article to a working paper I wrote about more scientific papers in this area. It is not polished, but it has the stuff.
Unlike the many and mysterious proteins in stones, citrate is a small molecule we measure in every kidney stone urine study, a molecule with well known abilities to reduce the rate of crystal growth and prevent stones. The article, like the protein article, is demanding but essential if one wants to understand how this simple molecule can be so important as it is. We will visit citrate again, over and over, but here it is in the context of the stones themselves.
Certainly it would be a terrible tour company that offered nothing by way of an exposition after supper. This article considers the problem of the stone crystals in a larger scientific context, and explores what science does and how it attempts to discover in the special province of Medicine. It is part of the series on ‘Site Logic’.
Physicians encounter stones in patients, and always have done so, but they themselves, as physicians, cannot determine what the stones contain, their crystals, their proteins. Scientists do that. The roles differ even in the uncommon situation where a physician is also a practicing scientist. How, then, so medicine and science work together? I say it is marriage – a true commons – and within it is a middle ground across which materials, ideas, and discoveries flow. The common kidney stone offers a perfect example.
Fred Coe, your tour guide.