304 W. I. Card and I. N. Marks 



than 35 kg. she was losing the equivalent of about 15 per cent 

 of her body weight daily through the fistula. 



The patient during this time was, of course, extremely ill 

 with consistently rapid pulse and occasional fever. Towards 

 the end of a month, however, an entirely new symptomato- 

 logy appeared. It was noticed that the patient became 

 excitable, apprehensive, and required doses of sedatives some 

 three or four times what would ordinarily be adequate. It 

 was indeed difficult to procure sleep. This excitable mental 

 state was an entirely new clinical picture to us and we finally 

 wondered whether it might not be due to magnesium de- 

 ficiency. Signs of tetany, in the sense of peripheral neuro- 

 muscular irritability, were lacking. An electrocardiogram was 

 within normal limits. Her serum calcium was 8-1 mg. per 

 cent. 



Arrangements were therefore made for serum magnesium 

 estimations and magnesium sulphate was given intravenously. 

 In 24-48 hours the state of the patient altered very consider- 

 ably, the excitement disappeared and the ordinary doses of 

 sedative were able to induce sleep. Magnesium therapy was 

 therefore continued to repair the deficit, and balance studies 

 were started and continued for some three weeks. All mag- 

 nesium therapy was given intravenously and the magnesium 

 ingested orally was not increased. This is important in the 

 light of subsequent calculations. 



Table I shows how the deficit prior to the institution of 

 therapy was calculated. It should be made clear that the loss 

 of fluid by fistula could not be measured directly, since a 

 complete collection was quite impossible. It was calculated 

 as follows : — 



Fistula fluid loss = (Oral + Intravenous) Intake + 



Metabolic water — (Urinary output + Extrarenal loss). 



Calculated in this way the total volume of fistula loss over 

 the period was 109-4 litres. The magnesium content of the 

 fistula fluid before therapy was started was never measured. 

 We have therefore made the assumption that intravenous 



