In this article we will discuss about the History and Advancement of Clinical Biochemistry.
Clinical Biochemistry:
From the time of Hippocrates (C.460-C.375 B.C.) the crude examination of body fluids including urine had been done. Thomas Willis, in the second half of the 17th century wrote a dissertation on urine and did the sweet taste to differentiate between the two types of diabetes.
Boerhaave of Leyden (1688-1738), who had much influence on medicine, taught quite confidently that medical phenomena could be interpreted in terms of chemistry. Physicians had long been interested in urinary calculi. Richard Bright in 1836 showed the relation of albuminous urine with Kidney disease. He did this by heating urine in a spoon and showed that cloudiness developed just before boiling.
In nineteenth century, Henry Bence Jones whose name is associated with “protein” and J. W. L. Thudichum became lecturer in chemical pathology at St. Thomas’ Hospital, London.
Alfred Garrod, just over 100 years ago, first did quantitative analytical methods applied to blood and at about this time, a number of well-known qualitative tests for urine had been done. By the end of the nineteenth century much of modern urine testing had already been done.
At the commencement of the 20th century “Clinical Chemistry” really began to develop into the discipline which we know today. Quantitative tests were carried out in regard to sugar and urea of urine and a series of qualitative tests for acetone, albumin, bile, and sugar were performed.
Different techniques now began to appear, mainly in the United States, for quantitative estimations applied to blood. In 1912, Folin and Denis described the phosphotungstic acid reagent for uric acid; in 1913, Bang described his micro-method for blood sugar, and Van den Bergh used Ehrlich’s diazo-reagent for the determination of bilirubin.
In 1915, Maclean and Van Slyke published their iodo-metric method for chloride. In the same year, the Liebermann-Burchard reaction was applied to the determination of cholesterol in blood. The newly introduced clinical application of insulin to the treatment of diabetes greatly stimulated urine and blood sugar estimations as well as those of electrolytes.
The range of quantitative tests performed in the clinical chemistry laboratory increased remarkably during the years between the two world wars. The B.M.R. was also estimated as well as urea concentration tests, the phenol red excretion test, the fractional test meal, and the test for occult blood. Pancreatic disease was studied by means of urinary diastase, fecal fat, and muscle fibres in the feces.
In relation to neurological disease, cerebrospinal fluid was fairly well investigated. In 1930, there appeared Harrison’s Chemical Methods in Clinical Medicine and Stewart and Dunlop’s clinical chemistry in Practical Medicine. A year later, the two volumes of Peters and Van Slyke were published. These three publications undoubtedly formed the foundation for the numerous text books on the subject in circulation today.
In the late thirties in the United States and in the early forties in the United Kingdom, various types of photoelectric colorimeters had appeared resulting in the speeding up of routine clinical chemical work with accuracy.
Another great progress, in the middle and late forties, there was the appearance of the flame photometer which enabled the estimation of sodium and potassium in the body fluids to be done quite quickly and very accurately. This had helped the clinicians to treat the diseases such as diabetic coma.
In 1938, Callow published the use of the Zimmerman reaction to determine 17- Ketosteroids. This was the first of the steroid determinations applied for routine purposes. Satisfactory methods had been developed for the estimation of catecholamine’s and their metabolites, particularly in urine.
The more recent development of radio-immunological assay and protein-binding techniques has led to the estimation of the hormones themselves, both in blood and other biological fluids.
Bodansky as well as King and Armstrong, in the early thirties, introduced their techniques for phosphates estimation. Specific inhibition techniques then led to the estimation of prostatic acid phosphatase which played a great part in the diagnosis and control of therapy of prostatic carcinoma.
The estimation of aminotransferases, lactate dehydrogenase and a number of other intracellular enzymes had been done. Isoenzyme determination had also been performed. Techniques also became available for the estimation of trace elements by absorption spectrophotometer which gave accurate results for routine purposes.
Grabar and his associates in 1953 made a firm basis on Immunoelectrophoresis which gave detailed study on Para-Pro-teinemias. Individual serum proteins could be investigated also by other immunological techniques, including radio-immunoassay.
Tswett in 1906 described absorption chromatography, Adams and Holmes in 1936 ion-exchange chromatography, Martin and Synge in 1941 partition chromatography, Consden, Gordon and Martin in 1944 paper chromatography, Mottier, James and Martin in 1952 gas-liquid chromatography.
All these techniques are in current use by clinical chemists and have greatly increased the range of substances which can be investigated in relation to disease.
In the fifties and sixties, the improvement in the control of respiratory disorders, open-heart surgery, and renal dialysis had been made by the use of the Astrup technique. Hereditary metabolic disorders had been detected by microbiological methods.
Since clinical chemistry had achieved the status of a recognized discipline in its own right national societies devoted to the subject were formed in various countries. First formed in the Netherlands in 1947 and was soon followed by those in the United States of America and in the United Kingdom. Societies of clinical chemistry have now grown up all over the world.
The first journal, Clinical Chemistry, was published in 1955 by the United States. This was soon followed by Qiniea Chemiea Acta, and now numerous journals have been published in many parts of the world. In addition, there are a good number of excellent books dealing with details of analytical methodology.
Since the national societies had been formed, it was realized that problems related to clinical chemistry should be considered at an international level. This has led to the formation of the clinical chemical section of the International Union of Pure and Applied Chemistry (IUPAC) and the International Federation of Clinical Chemistry (IFCC). These organizations have a number of joint committees.
Sophisticated techniques of this kind will enable the clinical chemist to estimate relatively large numbers of metabolites in relatively to all amounts of blood, tissue fluid, tissue culture, and biopsy samples.
Such development must certainly lead to greater understanding of disease processes as well as to more accurate diagnostic procedures and therapeutic control.
The normal range of these estimations should also be known for detecting diseases. It is now becoming almost mandatory to abolish the old fashioned concept of “normal range” and replace it by “reference values”.
Normal Range for Clinical Biochemistry:
The so-called normal ranges were at first determined on specimens obtained from healthy medical students or laboratory staff. Factors such as bed-rest could effect certain important biochemical values.
Whatever method is used to determine ranges, it soon becomes obvious that these values are dependent on a whole variety of factors including method of collection and handling of the sample for analysis, time of collection, seasonal changes, laboratory analytical method employed, laboratory accuracy, patient’s age, sex, ethnic group, social class, diet, physiological factors such as pregnancy or environment, and so on.
There is also the effect of therapeutic agents on the analytical method employed as well as on the actual blood levels of certain constituents. Many of these variables can be standardized, and then it is possible to obtain so-called reference populations.
These must be defined in terms of the other factors, such as sex, age, ethnic group, social class, etc. It should be pointed out here that in this regard biochemical values resemble many other physical signs obtained at the bedside or by ancillary methods of investigation.
It may also be mentioned that there is the effect of disease itself on biochemical values, which in themselves are not diagnostic of that disease. For example, in renal disease, in addition to an increase of blood urea there is frequently an increase in blood urate. There is a rough clinical correlation.
The clinician learns to associate certain blood urate levels with appropriate increase in blood urea. If the level of the former is too high in relation to the latter, then the possibility of Gout is considered. The latter disease can also be associated with an increase in the blood urea as well as of blood urate and a similar reasoning process must be employed.
Under the above discussion, it indicates that, in relation to diagnosis, biochemical values are merely additional and frequently very important for physical signs. Biochemical findings, as with most physical signs, have significance only in relation to the history of the patient’s illness and the physician’s findings, at the bedside as well as from ancillary methods of investigation.
Maximum difficulty arises to obtain normal reference values in the elderly because of the presence of frequent diseases in them. Therefore, it is difficult to define the “normal” state. The meaningful values are just begun to obtain in pediatrics possibly because of difficulties of sample collection and emotional obstacles.
It will be essential to standardize analytical methodology to obtain meaningful “reference intervals” in all groups of patients. Necessity will come into force to set up reliable reference methods, by which other methods can be standardized.
This is particularly the case in relation to enzyme determination. It is also vital to report laboratory findings in terms of standard units. For this purpose, it has already been decided to adopt SI Units.
SI Units for Clinical Biochemistry:
The conference Generele des Poids et Mesures, in 1960, confirmed the Systeme International d’ Unites (SI), originally adopted in 1954. This system is now based on eight base units relation to eight basic kinds of quantity.
The katal has been included in the following table 45.1. It should be pointed out that a number of authorities believe that the concept catalytic amount is not really viable and its unit would really be derived rather than base. One could introduce the concept catalytic activity per litre (derived coherent unit) which would give a figure which would be the same as if the katal were employed.
The mole and the katal have already been defined. In order to define the Kelvin, it is necessary to state that 273.16 K represents the temperature interval between the absolute zero and the triple point of water.
Temperature is more commonly expressed in terms of Celsius temperature, which is the thermodynamic temperature minus 273.16 K, since the Celsius temperature at the triple point water is 0.01 degree Celsius (0.01°C). The former term “centigrade” should no longer be used. The steam point Celsius temperature is 100°C above the Celsius triple point of water. Other units can be derived from the base units.
Derived Coherent Units for Clinical Biochemistry:
These are the units constructed exclusively from base units. In this category, unit area (unit length x unit length) or unit velocity (unit length divided by unit time) can also be included. The coherent unit of volume is the cubic metre. For the purpose of clinical biochemistry, the litre has been retained as the unit and redefined as exactly one-thousandth part of a cubic metre.
Derived Non-Coherent Unit for Clinical Biochemistry:
These are the units constructed from base units and numerical factors, for example, milligram per decilitre. In other words, the numerical factors are multiples or submultiples, which can be denoted by prefixes as shown in table 45.2.
Certain derived coherent units are used in clinical biochemistry. The unit of force is the Newton (N) and IN = 1 kg m/s2 the unit of energy is the joule (J) and 1J = 1 Nm : 4.2 kg corresponds to 1 kcal (kilocalorie), and the latter unit, which is the medical calorie, will be placed out. The unit of power is watt (W) and 1W = 1J/s. The electrical units are volt (V), farad (F) and ohm (Ω):
1V = 1 W/A; 1F = 1 A/s/V; 1Ω = 1V/A.
Concentration can be expressed in two types of unit. Mass concentration is the mass component divided by the volume of the mixture (kg/1, gm./1, mg/1, etc.). Substance concentration is the amount of substance of the component divided by the volume of the mixture (mol/1, m mol/1, etc.). The latter form of expression is preferable if the molecular weight of the substance is known. It can also be used for formula units.
The multiplication factor is easily derived from the former ways of expressing mass concentration, since it equals η/ V x MW, where η is the numerical value in a stated volume V (measured in litres), MW is the molecular weight of the substance concerned. When concentration has been expressed as mEq/1, it is merely necessary to divide by the valency of the component being determined.
Certain standard abbreviations are also recommended as shown below:
A laboratory report of a measurement should ideally always indicate:
a. The system.
b. The component.
c. The kind of quantity.
d. The numerical value.
e. The unit.
It is also doubtful whether actually the words “substance concentration” will be included in the average laboratory report.