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Background: A large percentage (16% of maternal mortality in developed countries, compared to 9% in developing countries), is due to hypertensive disorders in pregnancy. The etiology of preeclampsia remains unknown, with poorly understood pathophysiology. Magnesium and calcium play an important role in vascular smooth muscle function and therefore a possible role in the development of preeclampsia. Aim: We aimed to compare serum magnesium and total calcium levels of preeclamptic and normal pregnant women at the Korle-Bu Teaching Hospital in Ghana. Patients and methods: A comparative cross-sectional study involving 30 normal pregnant and 30 preeclamptic women with >30 weeks gestation and aged 18-35 years, was conducted at the Korle-Bu Teaching Hospital. Magnesium and calcium were determined using a flame atomic absorption spectrometer. Results: Mean serum magnesium and total calcium levels in preeclamptic women were 0.70±0.15 and 2.13±0.30 mmol/L, respectively. Mean serum magnesium and total calcium levels in normal pregnant women were 0.76±0.14 and 2.13±0.35 mmol/L, respectively. There was a statistically nonsignificant difference in serum magnesium and total calcium in preeclamptic women compared to normal pregnant women, with p-values of 0.092 and 0.972, respectively. Conclusion: Serum magnesium and total calcium, therefore, seem not to differ in preeclamptic women compared to normal pregnant women in Ghana.
A comparative cross-sectional study was undertaken from March to June 2016 at the Korle-Bu Teaching Hospital, Ghana. The Korle-Bu Teaching Hospital is the largest tertiary referral hospital in Ghana with 17 clinical and diagnostic departments and a total bed capacity of 2,000, out of which 350 are in the Department of Gynaecology and Obstetrics. The hospital has a daily outpatient attendance of ~1,500 patients, out of whom ~100 are antenatal patients. About 10,000 to 12,000 deliveries are conducted per year at the hospital. All normal pregnant and preeclamptic women with gestations >30 weeks and aged between 18 and 35 years inclusive, visiting the antenatal clinic at the Department of Obstetrics and Gynaecology, constituted the target population, except pregnant women with renal disorders, chronic hypertension, gestational or preexisting diabetes mellitus, and those on magnesium and/or calcium therapy. Preeclampsia was diagnosed using a systolic blood pressure ≥140 mmHg and a diastolic blood pressure ≥90 mmHg plus a random urine sample proteinuria ≥1+ on dipstick.31 The sample size was determined based on a formula by Charan and Biswas32 considering a mean serum magnesium level of 0.58 mmol/L in preeclamptic women compared to 0.73 mmol/L in normal pregnant women33 at a power of 80% and a 5% significance level. Sixty pregnant women comprising 30 normal pregnant and 30 preeclamptic women with >30 weeks of gestation and between the ages of 18 and 35 years inclusive, who met the inclusion criteria were recruited consecutively and included in the study after obtaining written informed consent. After obtaining an informed consent, participants’ demographic characteristics (age, weight and height) were recorded on a structured data collection sheet. The blood pressure of the participants was measured using a mercury sphygmomanometer, twice in each participant 20 minutes apart and averaged, noting the systolic and diastolic blood pressures, from which the mean arterial pressure was calculated using the following formula: where Pulse pressure = systolic blood pressure – diastolic blood pressure Using a 5 mL syringe on a 19G hypodermic needle, 4 mL of venous blood was obtained from participants’ cubital vein under aseptic conditions. For most serum ions, samples are to be separated within 2 hours as recommended by the Clinical and Laboratory Standards Institute.34 Blood samples drawn were immediately placed in a plain test tube and sent to the laboratory for analysis. At the laboratory, the blood samples were centrifuged at 4,000 rpm for ~10 minutes to obtain the serum within 2 hours of sample collection, and subsequently stored at –20°C prior to analysis within 24 hours of sample collection. Serum magnesium and total serum calcium were determined using an atomic absorption spectrometer in an acetylene–air flame (Variant 240FS; Varian Australia Pty Ltd, VIC, Australia) with reference ranges of 0.74–1.03 mmol/L and 2.12–2.62 mmol/L, respectively. Data obtained were stored in Microsoft® Access database 2010 and analyzed with SPSS® software version 20. The age, parity, body mass index (BMI), systolic blood pressure, diastolic blood pressure and mean arterial pressure of the participants are presented as mean values ± SDs. The mean serum magnesium and total calcium levels of normal pregnant women and preeclamptic women were compared using an independent t-test and are presented in a bar chart. Pearson correlation coefficient was used to determine the association between mean arterial pressure and serum calcium and magnesium levels. A p-value <0.05 was considered statistically significant. The Ethical and Protocol Review Committee of the University of Ghana School of Medicine and Dentistry, which is affiliated to the Korle-Bu Teaching Hospital approved the study (protocol identification number: CHS-Et/M.4-P4.5/2015-2016).
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