Summary - Hypomagnesemia was associated with alcoholism in the late 1960s. In serum, magnesium exists in three fractions: protein bound, complex-bound and in a free ionized form. Only the free ionized fraction is biologically active. We compared the use of ionized (iMg) vs total (tMg) magnesium measurements in patients with confirmed ethanol ingestion and in chronic alcoholism. iMg was measured by the ISE method; tMg was measured spectrophotometrically with xylidyl blue in groups of patients with ethanol ingestion (n=91) and chronic alcoholics (n=64) at the end of their hospitalization without ethanol ingestion. These results were compared to those of the control group (n=74). iMg level was significantly lower in the ethanol-containing specimens (0.49±0.07 mmol/L, mean±SD) compared to the control group (0.55±0.06 mmol/L, p<0.05). In the group of chronic alcoholics, iMg (0.52±0.06 mmol/L) level was not significantly different compared to the control group. tMg level from the ethanol-containing specimens (0.91±0.13 mmol/L) was not significantly different from the controls (0.95±0.11 mmol/ L), but the tMg level in the group of chronic alcoholics (0.85±0.12 mmol/L) was significantly lower (p<0.05) compared to the controls. The correlations between the ethanol concentrations vs iMg and tMg concentrations were not significant. Measurement of serum iMg instead of tMg may be of advantage in assessing the appropriate management of patients with ethanol ingestion and chronic alcoholics.
Key words: Ionized magnesium, Total magnesium, Ethanol ingestion, Chronic alcoholism.
Magnesium is a cofactor for more than 300 enzymes and the second most abundant intracellular cation in the human body. Magnesium affects many cellular functions such as transport of potassium and calcium ions, modulation of signal transduction and energy metabolism.1
Deficiency of magnesium (measured as tMg) occurs frequently in chronic alcoholism and contributes to the increased incidence of cardiovascular disease and osteoporosis2. Magnesium deficiency in chronic alcoholism is primarily due to renal magnesium wasting and is exacerbated by dietary Mg deprivation, gastrointestinal losses with diarrhea or vomiting as well as the concomitant use of drugs such as diuretics and aminoglycosides.2 Hypomagnesemia is almost always documented through total serum values (tMg), but it has recently become user-friendly to assay the biologically active, ionised fraction (iMg). While ion selective electrodes for the measurement of free magnesium are available, these are not widely deployed for routine clinical use.
Recent data obtained through the use of the noninvasive technology suggest that alcohol induces hypertension, stroke and sudden death via its effects on intracellular iMg, which in turn alter the cellular and subcellular bioenergetics and promote an iCa overload.3 Alcohol ingestion can result in profoundly different actions on the cerebral circulation depending upon dose and physiological state. After the administration of an acute dose of alcohol to the experimental animals, brain iMg dropped rapidly and significantly.4'5 Several studies described a marked deficiency of total and ionized magnesium in chronic alcoholic and lower iMg (not tMg) in the ethanol-containing specimens.67 It was pointed out that the determination of iMg concentration in biological fluids is influenced by several factors, and values may differ when measured with different instruments.7 The observation of magnesium status in health and disease depends on which magnesium fraction is measured.17
In the present study we compared the use of iMg vs tMg in a group of patients with ethanol ingestion and in patients with chronic alcoholism, after a period of abstinence and health controls.
SUBJECTS AND METHODS
Three groups of subjects were examined from February 1st to September 31st, 2004. The first group consisted of 74 healthy individuals, randomly selected, of both sexes, aged between 25 and 50 years, without any clinical or laboratory signs of chronic alcoholism or acute alcohol ingestion. …