Bernhard Naunyn

Bernhard Naunyn: The Physician Who Gave Diabetic Death a Name

Before Bernhard Naunyn coined the word in the late 1870s, doctors watching diabetic patients slip into coma and die had no precise term for the process killing them — only a vague sense that something acidic was accumulating in the blood. Naunyn named it "acidosis," defined its biochemical basis as an excess of acid bodies in severe diabetes, and in doing so gave clinicians and researchers a concept exact enough to eventually be treated, decades before insulin made diabetic ketoacidosis something a patient could actually survive.

Berlin Training Under Frerichs

Naunyn was born September 2, 1839, in Berlin into a prominent East Prussian family. He studied medicine at the University of Berlin under some of the era's leading physicians — Lieberkühn, Reichert, and Friedrich Theodor von Frerichs — qualifying in 1862, then spent several years studying zoology and anatomy at Bonn through 1868. He began his clinical career as an assistant to Frerichs at Berlin's Charité Hospital, absorbing the exacting bedside diagnostic tradition of one of German medicine's most influential internists before striking out to build a research program of his own.

A Chair at Every Major German-Speaking University

Naunyn's career moved through a sequence of professorships that placed him at nearly every major center of German-language medicine of the era: Dorpat, now Tartu in Estonia, from 1868 to 1871; a brief tenure at Bern in 1871; Königsberg from 1872 to 1888; and finally Strasbourg from 1888 to 1905, where he succeeded the eminent Adolf Kussmaul. Each move widened the pool of students and collaborators he worked with, and by the time he retired to Baden-Baden in 1905, he had trained a generation of physician-scientists — among them Eichhorst, Oskar Minkowski, Schreiber, Stadelmann, Umber, and Weintraud — who carried his methods of combining laboratory chemistry with clinical observation into hospitals and universities across Europe.

Diabetes, Ketoacidosis, and the Coining of "Acidosis"

Naunyn's most consequential scientific act was terminological as much as experimental: in the late 1870s he coined "acidosis" to describe the excessive accumulation of acid compounds in the blood of patients with severe, uncontrolled diabetes, giving the fatal metabolic crisis a name and a defined biochemical mechanism rather than leaving it as an observed but unexplained clinical decline. He collaborated with Oskar Minkowski, whose own pancreatic research helped establish the organ's role in diabetes, and in 1898 Naunyn published *Der Diabetes Mellitus*, a foundational treatise that advanced dietary management of the disease and organized the field's metabolic understanding in the decades before insulin therapy existed. For patients with type 1 diabetes at the time, dietary regimens built on this kind of metabolic understanding were often the only intervention available between diagnosis and death.

Gallstones and a Sign Before Murphy's

Naunyn's second major body of work concerned diseases of the liver and biliary system. His 1892 monograph *Klinik der Cholelithiasis* was the first comprehensive scientific study of gallstone disease, tracing stone formation to altered bile composition and bile stasis rather than treating gallstones as an incidental finding; it was translated into English for the New Sydenham Society by A. E. Garrod in 1896, carrying his framework directly into British medical practice. He also described a clinical technique for detecting gallbladder tenderness through costal-margin palpation during inspiration — a maneuver that predates by more than a decade the sign that would eventually be credited to and named for the American surgeon John B. Murphy.

Building the Institutions of Experimental Medicine

Beyond his own research, Naunyn helped construct the institutional scaffolding of modern German internal medicine. In 1872 he co-founded the journal *Archiv für experimentelle Pathologie und Pharmakologie* with Oswald Schmiedeberg and Edwin Klebs, establishing experimental pharmacology as a distinct academic discipline with its own dedicated venue for publication. In 1896 he founded a second journal, *Mitteilungen aus den Grenzgebieten der Medizin und Chirurgie*, with surgeon Jan Mikulicz-Radecki, deliberately built to bridge internal medicine and surgery at a moment when the two fields rarely spoke to each other in print.

A Career Recognized, Never Nobeled

Naunyn was nominated for the Nobel Prize in Physiology or Medicine multiple times between 1905 and 1918 for his work on metabolic disease, and never received it — a gap some historians attribute partly to his advancing age relative to the prize committee's preferences during those years. He remained scientifically active well into retirement in Baden-Baden and died there on July 26, 1925, at eighty-five; his autobiography, *Erinnerungen, Gedanken und Meinungen*, was published posthumously.

Why Bernhard Is Called a Genius

Naunyn's genius was the classic nineteenth-century internist's genius: an unusual capacity to sit at the intersection of laboratory chemistry and bedside observation and produce, from that intersection, terms and frameworks precise enough that other physicians could build on them immediately. Coining "acidosis" was not a laboratory discovery in the sense of isolating a new compound; it was an act of conceptual clarification, naming and defining a process others had merely observed, that proved durable enough to remain in clinical use more than a century later. His body of work spans diabetes, gallstones, liver disease, blood coagulation, and nervous system syphilis, and colleagues of his own era regarded him as a giant of internal medicine. The honest complication is that Naunyn is not remembered for a single transformative breakthrough on the scale of insulin's discovery or germ theory; his repeated Nobel nominations went unrewarded, and his genius shows more in the breadth, precision, and institution-building of a working physician-scientist than in one singular flash of insight.

Legacy

The term "acidosis" that Naunyn coined remains standard medical vocabulary, still used every day in intensive care units to describe the exact metabolic crisis he first defined, and the journals he helped found outlived him by generations as fixtures of German experimental medicine.

Achievements

• Held posts at Imperial University of Dorpat, Charité and University of Strasbourg