Micro-Analysis in Medical Biochemistry

Five years have passed since the second edition of this book appeared, and Professor King now shares the authorship with his colleague at the Postgraduate School, Dr. Wotton. Many changes 'have been made in the text. There is a new section on Normal Values and on the Control of Laboratory Accuracy which is particularly interesting, including as it does an indication of the variations to be expected in estimations and their type of distribution. (One cannot help wondering, after reading this, if the authors are justified in giving such precise limits for normal values elsewhere in sthe text, as for instance, on page 42, where the normal plasma cholesterol is said to lie between 153 and 26o mg./Ioo ml. !) Reference to the use of the Duboscq type of colorimeter has been omitted, and it is everywhere assumed that photo-electric absorptiometers are being used; it is surprising, therefore (particularly after the brief mathematical approach to the problem of variation) to, find that directions are given under each method for calculating the concentration of the unknown from the reading of a single standard. To assume that Beer's Law is universally valid (even for such a wayward substance as creatinine) seems to be unjustified. In any case, most laboratories are probably in the habit of constructing, and frequently checking, calibration curves. Many new and valuable methods are included, and there are new sections on the techniques of metabolic balance studies, of radioisotope studies and of flame photometry. In the last case, the details given apply to the E.E.L. flame photometer but the instructions given for the concentrations of the standards do not appear to be the ones most convenient for this instrument. In dealing with potassium estimations it seems important to stress the need for avoiding haemolysis, since this is such a common source of error. The section on Renal Clearance Techniques now includes the method of Roe, Epstein and Goldstein for Inulin, a welcome addition, but is unorthodox in advocating trichloacetic acid precipitation of plasma proteins, instead of cadmium hydroxide, iri the estimation of P.A.H. Other minor critici-ims might be made, but the book remains an important guide for everyone instrested in clinical biochemistry.