The significance of blood and cerebrospinal fluid urea levels estimated after death.

Doubt exists regarding the significance and diagnostic value of raised urea levels found in blood and cerebrospinal fluid after death. Harrison (1947), for instance, considers that in the present state of knowledge of post-mortem chemistry such estimations are without value, as high results are often obtained in moribund patients without kidney disease, and he also suggested that post-mortem changes occur which might influence the urea level. Some workers found post-mortem blood and C.S.F. urea estimations of limited value (Polayes, Hershey, and Lederer, 1930; Hamilton, 1938; Naumann, 1949, 1950; Tarsitano, 1950), but none of them attempted to determine by repeated estimations the degree of change in the blood urea level during the important agonal period. It may be of value when considering a cause of death to know whether a high post-mortem urea level represents an agonal rise, a post-mortem change, or urea retention during life with or without renal damage. This paper concerns the relationship of the pre-agonal and agonal blood urea levels to the post-mortem blood and C.S.F. levels, and an interpretation of the results in the light of the clinical and full post-mortem findings. The conclusion reached is that post-mortem urea levels, particularly those in C.S.F., are of value in diagnosis.