although many paradigms have been explored to minimize the mortality in critical care units , magnesium loss has been scarcely addressed ; in this respect leading to inconclusive results . serum magnesium monitoring may have prognostic and perhaps therapeutic implications because critically ill - patients are predisposed to both symptomatic or asymptomatic magnesium deficiency that can lead to some important clinical consequences ( such as hypokalemia , cardiac arrhythmias , hypocalcemia , neurotoxicity and psychiatric problems ) , ultimately increasing the morbidity and mortality . there is a paucity of data in indian literature , addressing this common , but underdiagnosed electrolyte deficiency . present study was undertaken against this backdrop at a tertiary care teaching hospital to assess the magnitude of magnesium deficiency and its influence on the outcome of critically ill - patients so that baseline reference data for insight and management of the problem in routine cases in our intensive care units ( icus ) is formed . this study was undertaken in a tertiary care teaching hospital of north india , over a period of 2 years . the study was started after getting clearance from the ethical committee , which is an independently functioning body of this institute . a detailed protocol was presented and discussed with the committee before the start of the study . it was a prospective observational study , which involved patients from both the medical and surgical icus . patients were enrolled at random and the selection bias was avoided by registering those patients who fulfilled the criteria for critical illness and who were newly admitted to icu . thus , the condition of subjects was first demarcated as critical who fulfilled the criterion of minimal physiologic reserve , requiring life support until abnormalities have been reversed , undergone massive disruption of physiology , requiring intensive monitoring in anticipation of possible aggressive intervention or post - operative cares . those patients were included who had 1 organ failure ( acute respiratory failure , acute liver failure , acute renal failure , septicemia , acute myocardial infarction , cerebrovascular accidents or multiorgan failure ) . post - operative ( especially major thoracoabdoninal surgery ) and polytrauma patients were also included . only those patients were included in which it was possible to take day 1 sample for serum magnesium . critically ill - patients in which day 1 of icu stay was missed were excluded . patients who were stable and did not fulfill the criteria for icu admission or who were in the general wards of the hospital were excluded . furthermore , the patients who had documented hypomagnesemia before the icu admission or who were on magnesium supplementation were excluded . patients were enrolled for the study after informed consent was given by first - degree relatives of critically ill - patients in the presence of two witnesses . demographic data ( age and sex ) , medical history , surgical history , medications administrated and length of icu stay were recorded for each patient . the severity scoring system used was acute physiology and chronic health evaluation - ii ( apache - ii ) which includes acute physiology score , glasgow coma scale , points assigned to age with chronic disease and chronic health condition score . other investigations such as arterial blood gases , complete blood count , kidney function tests , liver function tests , serum electrolytes , electrocardiography , chest x - ray and ultrasonography were also done . blood , urine and endotracheal secretions were sent for culture screen in every febrile patient . about 1 ml of venous blood was taken after informed consent from the patient 's first degree relative on day 1 and day 4 of icu admission and immediately used for sera separation . the blood was collected in green top vacutainers and made to stand for 30 min until centrifugation on 3000 rpm in a centrifuge ( sigma usa ) . the concentration of serum magnesium in the samples was determined by magnesium fluid monoreagent ( centronic gmbh - germany ) , a colorimetric endpoint method . the colored complex formed by magnesium with the monoreagent was read on a spectrophotometer ( shimadzu , japan ) in 1 ml cuvettes at 545 nm against reagent blank . normal range for magnesium concentration in our laboratory was 1.70 - 2.55 mg / dl . subjects were divided into normomagnesemic and hypomagnesemic groups and compared for various parameters . serum magnesium level of < 1.70 mg / dl was regarded as hypomagnesemia and 2.56 mg / dl as hypermagnesemia . analysis was performed by using test statistic student 's t - test for the difference of means , chi - square test , fisher 's exact test and correlation . these tests were further referenced for p values for their significance and p < 0.05 was considered to be significant . analysis was performed by using test statistic student 's t - test for the difference of means , chi - square test , fisher 's exact test and correlation . these tests were further referenced for p values for their significance and p < 0.05 was considered to be significant . we studied 70 critically ill - patients ( age > 16 years ) and followed their clinical as well as biochemical parameters from the day of admission to icu to the day of discharge from icu or death . septicemia , multiorgan dysfunction , respiratory failure and patients with major thoraco - abdominal surgery formed more than 50% of our study population [ table 1 ] . of 70 critically ill - patients , 71.43% were normomagnesemic , 24.29% were hypomagnesemic and 4.28% were hypermagnesemic . mean  sd of serum magnesium of hypomagnesemic patients was 1.63  0.06 mg / dl while as mean  sd of serum magnesium of normomagnesemic patients was 2.03  0.22 mg / dl . out of 17 critically ill hypomagnesemic patients , 13 patients had hypomagnesemia on day 1 and day 4 of icu admission while as four patients had hypomagnesemia on day 1 and normomagnesemia on day 4 of icu admission . there was no patient who had normomagnesemia on day 1 and hypomagnesemia on day 4 of icu admission . hypomagnesemic patients mostly comprised of multiorgan dysfunction ( 41.17% ) , respiratory failure ( 17.64% ) and septicemia ( 11.76% ) while as normomagnesemic patients had mostly septicemia ( 20% ) , post - operative course ( 16% ) , respiratory failure ( 14% ) , renal failure ( 10% ) and acute myocardial infarction ( 10% ) . out of three hypermagnesemic patients , two had renal failure and one had respiratory failure . age of hypomagnesemic patients ranged from 21 to 65 years ( males 10 and females 7 ) and that of normomagnesemic patients ranged from 16 to 80 years ( males 37 and females 13 ) . about 52.94% of hypomagnesemic population had a history of underlying chronic illness while as 44% of normomagnesemic population had such history ( p = 0.360 ) . distribution of 70 critically ill - patients mean apache - ii score of hypomagnesemic patients was 23.82  5.90 while that of normomagnesemic patients was 22.26  4.37 ( p = 0.34 ) . in addition , mean icu stay [ table 2 ] in our study was 5.53  4.32 and 5.66  3.99 days for hypomagnesemic and normomagnesemic groups respectively ( p > 0.05 ) . about 2/3 ( 76.47% ) of hypomagnesemic population was on magnesium lowering drugs ( mannitol , aminoglycosides and furosemide ) while as 46% of normomagnesemic population was on magnesium lowering drugs ( p = 0.030 ) . other associated findings were the electrolyte abnormalities such as hypokalemia ( 58.82% of hypomagnesemic patients ) , hyponatremia ( 47.05% of hypomagnesemic patients ) , hypocalcemia ( 70.58% of hypomagnesemic patients ) and hypophosphatemia ( 29.41% of hypomagnesemic patients ) . there was a highly significant difference in mortality between hypomagnesemic and normomagnesemic patients [ table 3 ] . in hypomagnesemic patients , 76.47% ( 13/17 ) expired , while as out of normomagnesemic patients , 36% ( 18/50 ) expired ( p < 0.05 ) . comparison of hypomagnesemic and normomagnesemic critically ill - patients mortality distribution of hypomagnesemic critically ill - patients the physician must therefore rely on determination of serum magnesium to determine if a patient is magnesium deficient . the primary end points of this study were serum magnesium level and outcome of critically ill - patients . secondary outcome measures were the associated electrolyte disturbances and length of icu stay . in our study of 70 critically ill - patients , 17 ( 24.29% ) patients were hypomagnesemic , 50 ( 71.23% ) were normomagnesemic and 3 ( 4.28% ) were hypermagnesemic , signifying remarkable occurrence of hypomagnesemia in icu patients . magnesium deficiency has been found to co - exist in up to 40% of patients with other electrolyte abnormalities . there are multiple reasons for magnesium deficiency in critical care settings e.g. , decreased absorption caused by impaired gastrointestinal activity , malnutrition , renal wasting of various drugs ( e.g. , digoxin , gentamicin , loop diuretics etc . ) , diabetes mellitus , hypokalemia and hypocalcemia . genetic differences in magnesium utilization may account for differences in vulnerability to magnesium deficiency and differences in body responses to stress . in our study , we found 76.47% patients of hypomagnesemia were on magnesium lowering drugs while as 46% of normomagnesemic patients were on magnesium lowering drugs . diuretics acting at loop of henle such as furosemide have been shown by micropuncture studies to result in marked magnesium deficiency . aminoglycosides have been shown to cause reversible renal lesion that results in hypermagnesuria and hypomagnesemia . in a retrospective analysis of 179 children of a pediatric icu , it was found that hypomagnesemia was more often seen in patients receiving diuretics and aminoglycosides . proton pump inhibitor associated hypomagnesemia is a rare , but potentially life - threatening side - effect that has emerged only in the era of mass use of these agents . a higher mortality rate was detected in hypomagnesemia patients when compared with normomagnesemic patients by chernow et al . had found no difference in icu mortality between hypomagnesemic and normomagnesemic groups ( 18% vs. 17% ) ; but noted a higher mortality rate among hypermagnesemic patients . soliman et al . observed that patients who develop ionized hypomagnesemia during their icu stay have higher mortality rates ( 2 - 3 times higher ) . dabbagh et al . observed higher mortality rates in critically ill - patients with daily magnesium supplementation index ( dmsi ) < 1 g / day in comparison to dmsi > 1 g / day ( 43.5% vs. 17% ) . observed that mortality rate in hypomagnesemic group was 57% when compared with 31% in the normomagnesemic group . present study showed the mortality rate of hypomagnesemic patients 76.47% as compared to normomagnesemic patients ( 36% ) , almost similar results as previously reported . the higher mortality in our study can be ascribed to higher incidences of other electrolyte deficiencies and multiorgan dysfunction in the hypomagnesemic group when compared with normomagnesemic group . vital predictors of this deficiency are hypokalemia or hypocalcemia and considerable predisposing factor is the use of magnesium lowering drugs . there is an unfavorable outcome of critically ill hypomagnesemic patients irrespective of insignificant icu stay and apache - ii score . this study highlights the role of magnesium monitoring in critical illness and its value for favorable outcome . our study has a limitation of smaller size of study population to comment on similar icu stay , apache - ii score and co - morbidity ; for that a prospective study with larger sample size is needed .
background : magnesium is one of the major electrolytes , deficiency of which is frequently overlooked in critical illness , leading to an adverse clinical outcome if not monitored regularly.settings and design : single center prospective observational study of 2 years duration.materials and methods : the subjects studied were monitored for serum magnesium levels 2 times : day 1 and day 4 of intensive care unit ( icu ) admission . 
 patients were divided into normomagnesemic and hypomagnesemic groups and compared for various parameters.results:out of 70 critically ill - patients , 50 patients ( 71.43% ) were normomagnesemic , 17 patients ( 24.29% ) were hypomagnesemic and three patients were hypermagnesemic . 
 the stay of the patients in icu ( p > 0.05 ) , acute physiology and chronic health evaluation - ii ( apache - ii ) scoring ( p = 0.34 ) and co - morbidity ( p = 0.360 ) showed an insignificant variation between the two groups . 
 associated electrolyte abnormalities in hypomagnesemic patients were hypokalemia ( 58.82% ) , hyponatremia ( 47.05% ) , hypocalcemia ( 70.58% ) and hypophosphatemia ( 29.41% ) . about 76.47% of hypomagnesemic population was on magnesium lowering drugs while as 46% of normomagnesemic population was on magnesium lowering drugs ( p = 0.030 ) 
 . 
 mortality of hypomagnesemic group was 74.47% while that of normomagnesemic group was 36% ( p = 0.004).conclusion : hypomagnesemia is a significant electrolyte abnormality in critically ill - patients . 
 critically ill hypomagnesemic patients have higher mortality than the normomagnesemic patients .