The international nephrological community grieves for Prof. Dr. med. Eberhard Ritz, who passed away in Heidelberg, Germany on 29 October 2023 aged 85 years (Fig. 1). His patients, peers, and colleagues will miss a passionate physician, brilliant academic teacher, and outstanding scientist, who enthusiastically promoted advances in dialysis technology and the understanding of physiological principles of renal failure. His scientific contributions motivated generations of medical and bioengineering students to step into the once new realm of nephrology and related dialysis techniques whilst performing their doctoral thesis. Renal therapy could, thus, be brought to nearly perfection for the long-term clinical benefit of kidney patients. The medical community will also miss a popular lecturer throughout nearly all European countries and a competent discussant. Based on his linguistic competence, Ritz spoke fluent English, French, and Italian, and he was a highly welcome speaker in international scientific meetings because he attracted the curiosity of his audience for complex physiological details. Through his always constructive diplomatic attitude and based on his outstanding knowledge of the scientific literature, he was able to moderate controversies in scientific discussions by guiding them to acceptable conclusions. His interest for historical and cultural details allowed him to draw visionary conclusions for future medical therapies and the treatment of kidney patients, in particular. Eberhard Ritz never wanted to take centre stage in these discussions, he was the centre.

Eberhard Ritz was born in Heidelberg, Germany on 23 January 1938. During the difficult years before and during World War II, he was a pupil in Southern Bavaria, where he transiently lived together with his mother and sister. Back again in Heidelberg after the war, he graduated in 1957 and began his studies of medicine at the universities of Heidelberg, Munich, and Montpellier/France. He pursued his clinical education with studies on vascular problems and atherosclerosis in Zürich/CH in the group of Prof. Siegenthaler and as a postdoc of the National Institute of Health (NIH) in the Department of Biochemistry of St. Louis University in the USA with Prof. Kirk. Having returned to Germany in 1967, Ritz joined the Medical Clinic Heidelberg. He became chief of the Division of Nephrology in 1977 and was appointed professor for “internal medicine” in 1979. At the beginning of his academic career, Ritz expected to continue his research on cardiovascular complications and organ transplantation, but there was one thing, he hadn’t reckoned with. Instead of doing research on problems of human physiology, his department chief relocated him in order to start in the dialysis and nephrology department. Ritz was at first not “amused,” but the young discipline of nephrology became one of his “love affairs,” as mentioned later in an interview with the American pathologist Kim Solez (MD) [1]. Obviously and due to their broad knowledge and interests, gifted scientists need some guidance and pressure at the beginning of their career. Ritz shared this obligation with Stanley Shaldon, another pioneer of dialysis therapy and cofounder of the European Dialysis and Transplantation Association (EDTA). Shaldon once started his scientific investigations in hepatology until his department head and first female professor in medicine, the hepatologist Dame Sheila Sherlock at the Royal Free Hospital in London commanded him to switch to dialysis therapy in 1961.

The scientific work of such an internationally renowned scientist like Eberhard Ritz comprises more than 1,500 publications that are documented in PubMed. It would challenge the scope of this obituary, given that we would reference all these and mostly stellar manuscripts in detail. The personality and merits of the physician, teacher, scientist, and visionary Eberhard Ritz will be described instead in more detail.

Already at the beginning of his engagement as a nephrologist, Ritz had a close eye on medical device technology related to clinical haemodialysis, such as dialysis equipment and disposables and their impact on patient well-being. The term “machine doctor,” which was coined at that time, was far beyond his understanding of a caring physician. To optimize the high treatment burden of dialysis patients and understand involved physiological mechanisms, he investigated prominent topics of dialysis treatment of today, namely “Dialysis related bone disease [2],” “Hypercoagulability in uraemia [3],” and compared hemofiltration and haemodialysis for “Sympathetic activity” [4] among others already in the 1970s. He complained later that PubMed does not offer references to manuscripts published before 1975 [1] and is, thus, not accessible for students and physicians despite their groundbreaking research. Together with his peer, Jürgen Bommer, details affecting patients during dialysis treatment raised his interest, such as spallation of silicon particles from tubing [5], allergic reactions due to PVC tubing [6], ethylene oxide sterilization of dialysers [7], and water quality in dialysis [8]. In 2021, the Centres for Medicare and Medicaid Services (CMS) in the USA encouraged the greater use of home dialysis and implemented the “ESRD Treatment Choices Model (ETC)” [9], to provide better patient care under the premise of cost constraints. Already in 1969, the “Kuratorium for Home Dialysis (KFH)” was founded with the purpose to make dialysis available for kidney patients. Shortly afterwards, E. Ritz and his peer J. Bommer established a training centre for home dialysis in Heidelberg in 1972, although Heidelberg University clinic was not allowed to perform ambulant dialyses. As Ritz stated later, knowledge and permanent training of dialysis techniques are the essentials for the benefit of kidney patients.

Many international conferences profited from the profound teaching of complex details always combined with an entertaining element of Eberhard Ritz. Asked about his strategy to teach, he advised never to overload his audience with findings irrelevant to clinical practice, not to be too theoretical and insert from time to time a joke in the presentation. Reading his scientific publications, the interested reader will frequently find a question mark, both in the title and in subtitles within the text. Some examples may be referenced here: “Vascular calcification – is aldosterone a culprit?” [10], “Intestinal renal syndrome: mirage or reality?” [11], “Is there an obesity-metabolic syndrome related glomerulopathy?” [12], or “Salt – A potential ‘Uremic Toxin’?” [13]. Obviously, question marks in publication titles and subtitles were vehicles to raise the awareness and curiosity of a reader for a specific actual topic, whilst offering answers for clinical solutions.

The performance and improvement of medical devices for the treatment of kidney failure depend on the manufacturer’s understanding of underlying principles, which may lead to technological excellence. Thus, many bioengineers from the MedTech industry were invited by E. Ritz to visit the nephrology department of Heidelberg University Clinic either for a course, a PhD thesis, or intense discussions. As a result, they received a detailed education on physiological principles combined with practical advices on nephrological reality in a dialysis centre with focus on patient well-being.

Together with his peer, Prof. Norbert Lameire from Ghent University in the years 2000 ff., Eberhard Ritz organized and performed seminars for advanced technological and clinical education entitled “Dialysis Academy” and realized both in Ghent/Belgium and in Heidelberg. Invited European young nephrologists will never forget the controversial discussions between the two protagonists, Lameire and Ritz. The audience was fascinated by their scientific comments flavoured with subtle irony and humorous remarks based on long-term experimental and theoretical knowledge and not excluding perspectives of clinical reality.

Further the internationally well-recognized annual Heidelberg Nephrology Seminar was founded by E. Ritz in 1976. It has attracted and updated generations of nephrologists till date and proves the intention of E. Ritz to propagate recent scientific findings and put them in perspective.

When Kim Solez asked about his favourite scientific topics [1], Eberhard Ritz confessed to have had three “love affairs,” which stimulated his scientific interest most, namely calcium metabolism, diabetes, and the hormone aldosterone. Numerous publications on these topics have fascinated the nephrological community. Ritz was able to review and combine these topics and put them in perspective, such as in a review, entitled “Atherosclerosis in dialysed patients” [14]. Concerning aldosterone [10, 15], he commented and outlined a more general approach to the hormone that “…apart from the classical endocrine action, i.e., causing blood pressure elevation as a result of salt retention, aldosterone has numerous blood-pressure-independent actions on nonepithelial tissue. Under conditions of high salt concentration, aldosterone is injurious to the kidney, heart, and vasculature” [15]. His consequent advice, that salt may be added to the list of uremic toxins [13], shows his epidemiologic visions. The interested reader may also be impressed by the unbiased scientific attitude of Ritz and his collaborating peers, shown in an introduction to a publication on bicarbonate dialysis [16] and as indicated above, the paper entitled “Bicarbonate dialysis – so what?” has a question mark. It reads: “The authors of this contribution may have perfect scientific credentials to discuss the above problem, because with the exception of one study we never did research on this subject. However, on the other hand, this may be an advantage in disguise, since we do not have an ax to grind and can look at the problem dispassionately from a certain intellectual distance!” [16].

Ritz’ native modesty, when it was about himself comes up, when he was asked about the most influential scientists, who provides ideas and advice, namely Prof. Karl Julius Ullrich from the Max-Planck Institute in Frankfurt, Prof. A. Heidland from Würzburg University, and Dr. B. Scribner from Seattle University, adding to the list all his collaborators without their contributions and environment of trust research in his department would not have been possible.

The treatment of kidney patients by haemodialysis has undergone a metamorphosis in the last 2 decades and has assumed a commodity therapy. As an epidemiologist and far-seeing visionary, Ritz foresaw already in 1999 the impact of diabetes on the future global prevalence of kidney disease [17]. He was also aware of the fact that the development of new pharmaceutical drugs would considerably impact dialysis therapy and related economic conditions. As an example, SGLT-2 inhibitors and the recombinant GLP-1-receptor-agonist semaglutide, will both, efficiently affect the treatment of diabetes. Consequently, the risk of progression of chronic kidney failure and cardiovascular outcomes will be reduced [18, 19]. It can be assumed that Ritz as a visionary was certainly sympathetic with, but would critically assess, the strategy of the American Kidney Foundation to advance quality through the “Kidney Disease Outcomes Quality Initiative.” This initiative applies penalties to dialysis facilities payments based on quality metrics across four major domains: clinical, care coordination, safety, and patient and family engagement [20], although pay-for-performance has not yet proven successfully in medical treatments [21]. He would have certainly promoted the “End-Stage Renal Disease Treatment Choices Model,” which encourages the greater use of home dialysis and kidney transplants in the USA [9].

A clinical discipline, such as nephrology, would lose its attraction without the propagation of renowned personalities, such as Eberhard Ritz. As a co-editor of the journal “Nephrology Dialysis and Transplantation” between 1993 and 1999, he successfully provided a platform for the science of nephrology. He served as a board member of many nephrological societies, both in Germany (GFN), in Europe (ERA-EDTA), and internationally as a president of the ISN from 2007 to 2009. As a result, many national nephrological societies awarded him with honorary memberships, whilst he received an honorary doctoral degree by the universities of Katowice and Szczecin in Poland, Budapest in Hungary, and Iasi in Romania.

Eberhard Ritz’ knowledge in science, medicine, history, and music was unparalleled and supportive for the education of his colleagues and friends. His dedication to facilitate international scientific cooperation across boundaries based on friendship and enthusiasm will be unforgettable. Together with his wife Dr. Christina Ritz and his four children, the international nephrological community has lost one of his esteemed members and protagonists. His friends and colleagues say farewell to a true pioneer and visionary.

Additional Information

*“Whatever you do, do it wisely and consider the end!” Re: Gesta Romanorum, Middle Ages.

1.
Legacy interview with pioneers of European nephrology by Kim Solez. You tube video
.
2018
.
2.
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,
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,
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,
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,
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F
.
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.
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.
1971
;
7
(
3
):
520
.
3.
Andrassy
K
,
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E
,
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,
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.
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.
Proc. EDTA
.
1971
;
8
:
546
9
.
4.
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U
,
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,
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,
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,
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.
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.
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.
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;
15
:
610
2
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5.
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6.
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91
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.
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11
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8
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,
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31
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6
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12.
Ritz
E
,
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.
Is there an obesity-metabolic syndrome related glomerulopathy
.
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.
2011
;
20
(
1
):
44
9
. .
13.
Ritz
E
,
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R
,
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,
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.
Salt: a potential ‘uremic toxin’
.
Blood Purif
.
2006
;
24
(
1
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63
6
. .
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Ritz
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,
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22
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28
7
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15.
Ritz
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N
.
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29
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3
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16.
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96
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17.
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,
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1999
;
34
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795
808
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2023
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89
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19.
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