HTN: Magnesium (2015)


Bayir A, Kara H, Ak A, Cander B, Kara F. Magnesium sulfate in emergency department patients with hypertension. Biol Trace Elem Res. 2009; 128: 38-44.

PubMed ID: 18953498
Study Design:
Randomized Controlled Trial
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Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To compare the effect of IV magnesium with other anti-hypertensives in emergency department (ED) patients with hypertension.
Inclusion Criteria:
  • SBP higher than 135mm Hg
  • DBP higher than 85mm Hg.
Exclusion Criteria:
  • Pregnancy
  • Symptoms or signs of hypertensive emergency
  • Neurologic deficit
  • History of head trauma in the previous week
  • Acute or chronic renal failure
  • Chest pain.
Description of Study Protocol:


Patients with hypertension presenting in emergency room were approached.


Randomized controlled trial.

Blinding Used

Implied with measurements.


Subjects were randomly assigned to receive one of the following treatments:

  • Infusion of 1.5g IV magnesium sulfate over 30 minutes
  • Oral or IV anti-hypertensive agent as determined by examining physician (ACE inhibitor, calcium channel blocker, beta blocker or nitrate)
  • A total of 1.5g IV magnesium sulfate over 30 minutes with oral or IV anti-hypertensive agent.

Statistical Analysis

  • Blood pressure changes over time calculated as percentages
  • One-way analysis of variance conducted with post-hoc Tukey HSD Test
  • Chi-square test for categorical data
  • Repeated measures compared by paired T-test with ANOVA Bonferroni correction.
Data Collection Summary:

Timing of Measurements

Blood pressure measured at 15 minutes, 30 minutes, 45 minutes and 60 minutes after medication administration.

Dependent Variables

Blood pressure was measured after resting for 10 minutes by emergency physicians using a sphygmomanometer.

Independent Variables

Subjects were randomly assigned to receive one of the following treatments:

  • Infusion of 1.5g IV magnesium sulfate over 30 minutes
  • Oral or IV anti-hypertensive agent as determined by examining physician (ACE inhibitor, calcium channel blocker, beta blocker or nitrate)
  • A total of 1.5g IV magnesium sulfate over 30 minutes with oral or IV anti-hypertensive agent.
Description of Actual Data Sample:
  • Initial N: N=144 patients with hypertension presented to the Emergency Department
  • Attrition (final N):  127 patients (57 females, 70 males)
  • Age: 59±10 years.
  • Significant differences in baseline Na, K and Mg levels were not found among the three groups. A significant difference in baseline Ca levels was found between the magnesium sulfate and anti-hypertensive groups (P=0.02).
  • Percentages with obesity among the three groups ranged from 9% to 15%; the significance not specified.
  • Baseline SBP (extrapolated from figure): Approximately 175 to 200mm Hg
  • Baseline DBP (extrapolated from figure): Approximately 95 to 110mm Hg




Summary of Results:

Key Findings

  • Compared to systolic blood pressure and diastolic blood pressures at time zero, both were lower at 15 minutes, 30 minutes, 45 minutes and 60 minutes in all groups (P<0.05)
  • No significant difference in systolic BP or diastolic BP at any time point was observed when response to treatment was compared between the three treatment groups:
    • Decrease in SBP (extrapolated from figure): Approximately 20mm Hg to 50mm Hg
    • Decrease in DBP (extrapolated from figure): Approximately 20mm Hg to 30mm Hg.
Author Conclusion:
Magnesium sulfate provided through an IV to emergency department patients with hypertension is an effective alternative to other anti-hypertensive agents.
Funding Source:
University/Hospital: Selcuk University, Turkey
Reviewer Comments:
A significant difference in baseline Ca levels was found between the magnesium sulfate and antihypertensive groups (P=0.02).
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? ???
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? ???
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes