Circulating ionized and total magnesium in end-stage kidney disease.
BACKGROUND
Circulating magnesium exists in the ionized state and in the undissociated form, either bound to albumin, or complexed to various anions. Until recently, only the measurement of total plasma magnesium has been possible. Now circulating ionized magnesium can be assessed as well.


METHODS
Total and ionized plasma magnesium were determined in 43 patients on maintenance hemodialysis (dialysate composition: calcium 1.75 mmol/l, magnesium 0.75 mmol/l) before a dialysis session and in a group of 23 healthy subjects.


RESULTS
The total (1.16 [1.03-1.31] versus 0.81 [0.78-0.89] mmol/l; median and interquartile range) and the ionized (0.71 [0.66-0.78] versus 0.54 [0.53-0.59] mmol/l) plasma magnesium levels were significantly higher (p < 0.01) and the ionized plasma magnesium fraction lower (0.61 [0.58-0.65] versus 0.67 [0.64-0.70]; p < 0.02) in patients than in controls.


CONCLUSIONS
The determination of circulating ionized magnesium using selective electrodes is an attractive method to evaluate extracellular magnesium in kidney disease.
Pedrozzi
N E
NE
Department of Pediatrics, University of Bern, Switzerland.
Truttmann
A C
AC
Faraone
R
R
Descoeudres
C E
CE
Wermuth
B
B
Lüthy
C M
CM
Nuoffer
J M
JM
Frey
F J
FJ
Bianchetti
M G
MG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D002648:Child; D005260:Female; D006801:Humans; D007477:Ions; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy*; D008274:Magnesium / Q000097:blood*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis
D007477:Ions; D008274:Magnesium; D002118:Calcium