Léon Ambard (1876-1962) was born in Marseille (France). He studied at the Sorbonne in Paris where he received his medical degree in 1905. In the years 1909-1914 he was chief of the laboratory of the Department of Urology at the Necker Hospital. His task was to find a method for assessing renal function with the goals of: 1. prognosticating the effects on the kidneys of surgical operation on the urinary tract and 2. for the early detection of renal impairment. He successfully devised the Urea Secretory Constant which was named after him (Ambard’s Constant). He was able to establish the laws governing urea handling by the kidney in health and disease and attracted to the topic the most innovative physician scientists of those days including Thomas Addis and Donald Van Slyke. His findings ensured his promotion to Professor of Pharmacology at the University of Strasbourg in 1919. In 1930 he was nominated correspondent member of the National Academy of Medicine. In the same year he was promoted to professor of medicine. Ambard is credited with an impressive list of excellent papers and books including Physiologie Normale et Pathologique des Reins which had 3 editions (1914, 1921 and 1930). He retired in 1947 but remained very active till the end of his life (May 19, 1962). His last publication (Ultrafiltration) was written in English with Simone Trautmann (1961).
Keywords: Léon Ambard, Urea Secretory Constant, Urea Clearance, Thomas Addis, Donal D. Van Slyke, laws of renal urea excretion