HYPERNATRAEMIA AND HYPONATRAEMIA 



WITH SPECIAL REFERENCE TO 



CEREBRAL DISTURBANCES 



Paul Fourman and Patricia M. Leeson 



Medical Unit, Royal Infirmary, Cardiff 



Introduction 



An abnormal concentration of sodium in the extracellular 

 fluid often presents a puzzling problem for the clinician. As 

 is well known, a change in the total amount of the sodium or 

 of the water in the body can explain many instances — water 

 deficiency or sodium excess producing hypernatraemia, 

 water excess or sodium deficiency producing hyponatraemia. 

 But many cases appear to require more than a simple account 

 of gains and losses to explain them. Is this because a simple 

 explanation, such as a change in the amount of water in the 

 body, has been overlooked, or must one in such cases invoke 

 some new mechanism, possibly under the control of the 

 nervous system? 



There have been a number of reports of "cerebral" hyper- 

 natraemia and hyponatraemia (Knowles, 1956; Edelman, 

 1956). With regard to hypernatraemia it seems likely that 

 some of the contradictions in the present views (Welt et al., 

 1952; Higgins et al., 1954) might have been avoided, for in 

 hardly any of the patients reported could a frank water 

 deficiency confidently be excluded from the information 

 supplied. This question is discussed in the first section. The 

 subject of hyponatraemia seems much more difficult, but if 

 sodium deficiency is excluded, many of the remaining cases 

 can be accounted for by an abnormal retention of water 

 diluting the body fluids. In the second section we present 

 some new data on the problem, derived from a study of two 

 patients. 



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