Frequency of hypomagnesemia and hypermagnesemia. Requested vs routine
R. Whang and K. W. Ryder
Department of Medicine, Veterans Administration Hospital, University of Oklahoma Health Sciences Center, Oklahoma City.
This study was designed to assess the effectiveness of identifying serum
magnesium abnormalities by comparing physician-initiated requests for this
analyte with routine magnesium determinations. Because magnesium
abnormalities frequently accompany other electrolyte abnormalities, we
measured magnesium in 1033 serum specimens submitted for electrolyte
analyses. Physician-initiated requests for magnesium measurements were
received for 81 (7.4%) of these specimens. Serum magnesium abnormalities
were identified in 546 of the 1033 specimens (hypomagnesemia [less than
0.74 mmol/L], 487; hypermagnesemia [greater than 0.99 mmol/L], 59). Only
10% of the hypomagnesemic patients (48/487) and 13% of the hypermagnesemic
patients (7/59) were identified by physician-initiated requests for this
analyte. Fifty-three patients were both hypomagnesemic/hypokalemic and 30
patients were both hypomagnesemic/hyponatremic, but only 8 (15%) and 3
(10%), respectively, had physician-initiated requests for magnesium.
Because magnesium abnormalities in significant numbers of patients are not
being detected, we recommend routine measurement of this analyte when
analyses of electrolytes are required for the care of patients.
