Urinalysis in clinical diagnosis.

It is appropriate to commence this article on the history of urine examination with the words of Auguste Comte (1798-1857), who wrote in Positive Philosophy that "To understand a science it is necessary to know its history".' In this context and with special reference to urine, the most freely accessible of all biological fluids, it is not surprising to know that over the course of history it was probably the first body fluid to be studied scientifically. Indeed, it was Count Antoine Francois de Fourcroy (17551809) who stated in A general system ofchemical knowledge, and its application to the phenomena of nature and art, Volume X, Article 25 (translated by W Nicholson), that "The urine of man is one of the animal matters that have been most examined by chemists, and of which the examination has at the same time furnished the most singular discoveries to chemistry, and the most useful application to physiology, as well as the art of healing. This liquid, which commonly inspires men only with contempt and disgust, which is generally ranked amongst vile and repulsive matters, has become, in the hands of the chemists, a source of important discoveries".I One of the earliest references pertaining to the diagnostic value of studying urine is found in the ancient Sanskrit literature. Ants and other insects were observed to accumulate selectively around the sites of urination of certain individuals; this was referred to as "honey urine" or "sugar cane urine", the insects having been attracted to the sweet flavour and meaty smell. The urine had, of course, been passed by people with diabetes mellitus; similar observations had already been reported by ancient Chinese physicians.2 Ancient medical texts from Mesopotamia also reveal carefully documented observations on the appearance of urine; there was note, in particular, of the changes in odour and colour.' The earliest procedure described in the literature which could be specifically regarded as a diagnostic test was used, not only to confirm pregnancy, but also to identify the sex of a foetus. These tests were performed about 1000 BC by Egyptian priests who poured urine over mixed cereal seeds. It seems that if germination occurred then the test was regarded as positive; however, it is stated that only by noting the actual type of seed that germinated was it possible to predict the sex of the foetus.' Uroscopy, which was inspection of the urine for diagnostic purposes, had been practised by Hippocrates (460-370 BC); he attempted to link his observations with the doctrine of the four humours-namely phlegm, blood, yellow bile and black bile, which had been proposed earlier by Aristotle (384-322 BC). Aristotle had regarded health as a balance between these four biological components.4 In Hippocrates' Book of Prognostics there is a paragraph on uroscopy, in which he described the changes he observed in the composition of urine during the course of fever, both in children and adults; he also included differences in colour and odour.4 Inspection of urine in its container was at that time considered to be an effective way of demonstrating, not only fundamental changes in balance of the four humours, but also location of disease within the body; this practise was used for prognostic purposes, too. Uroscopy (which comprised observations on colour, consistency, quantity, transparency, odour, and the presence or absence of froth) was to be part of the diagnostic repertoire for some considerable time and, indeed, was practised by Galen of Pergamum (129 to approx. 199), the Byzantines and the Arabs. Avicenna (980-1037), whose full name was Abu Ali Husain ibn Abdullah ibn Sina, in his vast tome of medical knowledge entitled Canon, developed the art further by taking into consideration the conditions that should be observed prior to collection of a urine sample; he included observations that would enable differentiation of urine samples from other similar liquors that might have been brought with the patient in order to "test the competence of the physician".5 (Perhaps this was one of the earliest attempts at quality control!) In the thirteenth century Gilles de Corbeil (?1 165-1213), in his analysis of urine inspection, regarded the sample in the urinal as being divisible into four levels, each of which represented the various parts of the body; the uppermost level represented the head, the next the chest, the third the abdomen, and the lowermost level, the urogenital organs.6 During the middle ages there was no further progress and uroscopy became the trademark of physicians, even being portrayed in some paintings in which it was not uncommon for a urine glass to represent the sign of a physician (fig 1). This should not, of course, be confused with the uromancers who were popular at that time; they claimed to possess the ability, not only to define disease states by examining the urine, but also to foretell the future. Uromancy was soon to be practised quite widely, being accepted by surgeons, charlatans, apothecaries, Department of Pathology and Bacteriology, University of Oxford, John Radcliffe Hospital, Headington, Oxford J Bolodeoku