A Case of Magnesium Deficiency 



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magnesium therapy does not alter the output of faecal 

 magnesium (McCance and Widdowson, 1939) and that this is 

 also true of the magnesium content of ileal fluid. If this 

 assumption is true, then we can calculate the magnesium 

 content before therapy by measuring it in the fistulous fluid 

 after therapy had started. On 18 days a sample of ileal fluid 

 was measured and the mean magnesium concentration was 



Table I 

 Magnesium deficiency — A.M. 



18 AprU-19 May, 1954. 

 Volume of fistula loss = (Oral + Intravenous) Intake + Metabolic water 

 — (Urinary output + Extrarenal loss) 

 = 109-4 1. 



Magnesium loss 



Fistula = 109-4 x 4-1 = 447 m-equiv. 

 Urinary = 19-4 x ? 1 = 19 m-equiv. 



Magnesium intake 



Oral = 105 m-equiv. 

 Intravenous = 15 m-equiv. 



Total = 466 m-equiv. 



Total =120 m-equiv. 

 Balance = —346 m-equiv. 



Body weight 17.4.54 = 34 kg. 



less fat 7% = 31-6 kg. 

 Body Mg at onset = 31-6 X -45 = 14-2 g. = 1180 m-equiv. 



Deficit = 29 % 



4-1 m-equiv. /I. The total loss of magnesium through the 

 fistula can now be calculated and is 447 m-equiv. 



The urinary loss of magnesium cannot be measured in this 

 way since the infusion of magnesium salts has been reported 

 to increase the amount put out by the kidney (McCance 

 and Widdowson, 1939) and this was certainly true in this 

 patient. Since the kidney was functioning well as judged by 

 its concentrating power, the urinary concentration in the 

 period before symptoms occurred probably never rose above 

 1 m-equiv./l. This gives a total urinary loss of 19 m-equiv. 



