The relationship between ionized and total serum magnesium concentrations during abdominal surgery.
OBJECTIVE
To determine the necessity for ionized magnesium (iMg) assay by evaluating the effect of abdominal surgery without massive transfusion on total magnesium (Mg) and iMg concentrations.


METHODS
Prospective, observational study.


METHODS
Operating rooms at a university teaching hospital.


METHODS
31 patients without electrolyte abnormalities who were scheduled for abdominal surgery.


METHODS
None.


METHODS
Serum electrolytes, iMg, ionized calcium, proteins before and after surgery, and urine Mg were recorded.


RESULTS
Total Mg and iMg decreased: Mg 23%, iMg 15%; p < 0.0001. Total and iMg were highly correlated (r = 0.728, p < 0.0001). Urine Mg output remained within normal limits (mean 0.24 mmol/hr).


CONCLUSIONS
During abdominal surgery without massive transfusion, both total and ionized hypomagnesemia occur. Changes in iMg and total serum Mg concentrations are closely correlated. Total serum Mg assay, while overestimating the prevalence of ionized hypomagnesemia, is sufficient to screen for hypomagnesemia.
Lanzinger
Marcella J
MJ
Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA. lanzi001@mc.duke.edu
Moretti
Eugene W
EW
Wilderman
Robert F
RF
El-Moalem
Habib E
HE
Toffaletti
John G
JG
Moon
Richard E
RE
D000005:Abdomen / Q000601:surgery*; D000328:Adult; D000418:Albumins / Q000032:analysis; D000768:Anesthesia, General; D001798:Blood Proteins / Q000032:analysis; D002118:Calcium / Q000097:blood; D004573:Electrolytes / Q000097:blood; D005260:Female; D006801:Humans; D007477:Ions; D008274:Magnesium / Q000097:blood* / Q000652:urine; D008297:Male; D011446:Prospective Studies; D013514:Surgical Procedures, Operative
D000418:Albumins; D001798:Blood Proteins; D004573:Electrolytes; D007477:Ions; D008274:Magnesium; D002118:Calcium