94 R. E. Tunbridge 



Numerous reports have been published during the past 

 twenty years, attempting to correlate the values for certain 

 functions — renal, cardiovascular, respiratory — with chrono- 

 logical age. Prof. Verzar and Dr. Landowne have already 

 referred to the results obtained by the use of some such 

 tests. Clinicians and pathologists have also reported variations 

 in the values for many of the principal constituents of the 

 blood with age. There are many potential fallacies in such 

 reports, those due to the method of sampling, to the inter- 

 pretation of the norm and to errors inherent in the technique. 

 Many of these points have already been referred to in this 

 symposium and I do not wish to labour them. The matter of 

 the sample is most important and so rarely has a truly 

 representative sample of the total population been studied. 

 The recent survey by Hobson and Pemberton (1955) was 

 based on what the statisticians would accept as a fairly 

 reliable cross-section of the city population of Sheffield. 

 These workers attempted a correlation of the haemoglobin 

 levels, blood urea, blood cholesterol, serum calcium and serum 

 alkaline phosphatase with chronological age. The results for 

 the serum alkaline phosphatase illustrate the inherent diffi- 

 culties in interpreting results and the difficulty of assessing 

 the norm. The findings were very closely grouped, with the 

 exception of eleven, seven males and four females, in all of 

 whom the value was abnormally high. In eight of these 

 individuals, six males and two females, further investigation 

 revealed that they were suffering from osteitis deformans 

 ( Paget' s disease). No specific cause was found for the high 

 value in the remaining three patients but it does not neces- 

 sarily follow that the latter were not suffering from some 

 disease in a clinically quiescent phase or from a disability for 

 which they had been able in part to compensate. 



There is always the difficulty of deciding what is normal, 

 and this criticism must be applied to the majority of the 

 clinical surveys of ageing populations. Certain pioneer 

 surveys, such as the survey of Wolverhampton by Sheldon 

 (1948), were invaluable in focussing attention upon the medical 



