Large kindred. Critical Care Medicine
Volume 28 • Number 6 • June 2000
Copyright © 2000 Lippincott Williams & Wilkins
2022Hypomagnesemia and hypophosphatemia at admission in patients with severe
Head injurykees H. Polderman MD, phd 1Frank W. Bloemers MD 1Saskia M. Peerdeman MD 1Armand R. J. Girbes MD, phd 1
1 From the Surgical Intensive Care
Unit (Drs. Polderman and Girbes) and the Departments of Surgery (Dr.
Bloemers) and Neurosurgery (Dr. Peerdeman), University Hospital Vrije
Universiteit, Amsterdam, The Netherlands.
Copyright © 2000 by Lippincott Williams & Wilkins
Objective: Low serum levels of electrolytes such as magnesium (Mg),
Potassium (K), calcium (Ca), and phosphate (P) can lead to a number of clinical
Problems in intensive care unit (ICU) patients, including hypertension, coronary
Vasoconstriction, disturbances in heart rhythm, and muscle weakness. Loss of
These electrolytes can be caused, among other things, by increased urinary
Excretion. Cerebral injury can lead to polyuresis through a variety of
Mechanisms. We hypothesized that patients with cranial trauma might be at risk
For electrolyte loss through increased diuresis. The objective of this study was
To assess levels of Mg, P, and K at admission in patients with severe head
Design: We measured plasma levels of Mg, P, K, Ca, and sodium at
Admission in 18 consecutive patients with severe head injury admitted to our ICU
(group 1). As controls, we used 19 trauma patients with two or more bone
Fractures but no significant cranial trauma (group 2).
Setting: University teaching hospital.
Patients: Eighteen patients with severe head injury admitted to our
Surgical ICU (group 1) and 19 controls (trauma patients with no significant
Cranial trauma; group 2).
Main Results: Electrolyte levels at admission (group 1 vs. Group 2;
Mean ± SD, units: mmol/L) were as follows. Mg,
0.57 ± 0.17 (range, 0.24-0.85) vs. 0.88 ± 0.21 (range, 0.66-1.42 mmol/L; p
<.01). P, 0.56 ± 0.15 (range, 0.20-0.92) vs. 1.11 ± 0.15 (range, 0.88-1.44
Mmol/L; p <.01). K, 3.54 ± 0.59 (range, 2.4-4.8) vs. 4.07 ± 0.45
(range, 3.6-4.8 mmol/L; p <.02). Ca, 2.02 ± 0.24 (range, 1.45-2.51)
Vs. 2.14 ± 0.20 (range, 1.88-2.46; p = NS). In group 1, 12/18 patients
Had Mg levels <0.70 mmol/L vs. 2/19 patients in group 2 ( p <.01);
In group 1, 11/18 patients had P levels below 0.60 mmol vs. 0/19 patients in
Group 2 ( p <.01). Moderate hypokalemia (K levels, <3.6 mmol/L) was
Present in 8/18 patients in group 1 vs. 1/19 patients in group 2 ( p
<.01). Severe hypokalemia (K levels, 3.0)
Was present in 4/18 patients in group 1 vs. 0/19 patients in group 2 ( p
Conclusion: We conclude that patients with severe head injury are at
High risk for the development of hypomagnesemia, hypophosphatemia, and
Hypokalemia. One of the causes of low electrolyte levels in these patients may
Be an increase in the urinary loss of various electrolytes caused by neurologic
Trauma. Mannitol administration may be a contributing factor. Intensivists
Should be aware of this potential problem. If necessary, adequate.