“Formation of urinary stones remains a mystery despite decades of research efforts. Unfortunately, that kind of research has stagnated”

As a young surgeon in the early 1970’s I was surprised to meet so many patients with acute stone colic. That was different from the impression I had from my medical studies. Subsequently, when I was clinically trained in the art of surgery it was obvious that whereas some stones were very easy to remove, others presented technical difficulties, sometimes of a nightmare character. Two questions emerged: Firstly, can we understand the mechanisms of stone formation and accordingly counteract stone formation and secondly, can the method for removal of complex renal stones be improved and facilitated?

In 1974 I had just finished a research project for a doctor’s degree in medical/clinical chemistry, with studies on the metabolism of vitamin B6 and I had defended my dissertation. My question now was how difficult will it be to understand the problem of pathological crystallization and stone formation in urine?

This was the short background to why I became interested in urine composition and how the process of abnormal crystal precipitation could result in stone formation. Not without local difficulties did I succeed to get a lab bench at the research laboratory in Linköping. At about the same time I also visited Bill Robertson in Leeds to learn something about methods to study crystallization.

Let me now return to the problem of stone formation. To expand the analyses of urine composition I had the favor to establish a fruitful collaboration with Lasse Larsson at the Department of Clinical Chemistry in Linköping. Easy access to routine analysis of urine composition laid the ground for several clinical improvements such as for instance formulation of the AP(CaOx) index, a practical parameter with which supersaturation of urine with CaOx could be clinically estimated. Numerous other analytical steps were applied to learn more about stone formation both during my time in Linköping (up to 1998) and subsequently in Stockholm. The importance of the balance between supersaturation and inhibition of crystal growth and crystal aggregation was demonstrated. The research efforts during these intensive years resulted in several dissertations. Close collaboration with Dr Torsten Denneberg also brought me in touch with the problem of cystine stone formation.

When, for various reasons, I was forced to finish my active stone research, my focus was on the importance of pH for the tubular crystallization of calcium phosphate and the subsequent development of CaOx stones. Unfortunately, at the time when molecular chemistry and molecular genetics generally were in focus of biochemical research it became increasingly difficult to get financial support for basic stone research. It is my impression, however, that several of the observations that emerged from our many studies still might be useful to imply in clinical practice. Butthe interest in biochemical issues among colleagues at my department was low and nobody was interested to continue the research. This lack of interest in biochemical questions became even more apparent with recent and more attractive technical improvements in endourology.

Unfortunately, so far there is no way to clinically dissolve CaOx stones and moreover, medical treatment became less interesting also from a patient perspective when the modern surgery had made stone removal so easy.

So, what has happened to urolithiasis research in general? It is obvious that shortage of funding is a major factor that negatively affected stone research. Young urologists’ enthusiasm for low-invasive stone removal is an important factor. In my opinion there is a low interest in medical aspects of stone disease, not only among urologists but also among nephrologists, at least in Sweden. When money mainly was allocated to endourological issues, what remained for medical stone research was the publication of a never-ending series of systematic reviews of what others had done, both in terms of surgical and medical aspects. That development in fact killed active research on stone formation and its prevention.

Now, back to the problems of stone surgery that I encountered as a young surgeon. To make a long story short, the invention of extracorporeal shock wave lithotripsy (SWL) came as gift sent from heaven. It was almost as a fairy-tale when Christian Chaussy in 1980 disintegrated the first renal stone non-invasively. The method was introduced in Linköping in 1985 and showed a capacity that was much more powerful and considerably more successful than initially expected. Subsequent experience showed that the method could be used also for both large and hard stones as well as for ureteral stones. Patients were treated without or with gentle auxiliary procedures such as ureteral catheters, ureteral stents, percutaneous catheters and chemolysis.

Moreover after a few years, stone treatment was carried out with only analgesics and sedatives instead of regional or general anesthesia. Important observation: Only few exceptional cases, difficult to treat with SWL were handled low-invasively with the simultaneously introduced methods percutaneous surgery or ureteroscopy. But what happened to SWL and why?

There is no doubt that during past years modern endourology has taken the leading place in stone removal from SWL. This is the consequence of less efficient lithotripters than we initially used. That was the manufacturers’ natural answer to urologists’ desire to carry out SWL without any kind of anesthesia or analgesics. Thereby, it was ignored that also the most powerful lithotripters that we had used were possible to run with only analgesics and sedatives.