INTRODUCTION
Preeclampsia is a pregnancy specific syndrome and is one of the leading cause of maternal and fetal morbidity and mortality. Preeclampsia is defined as the existence of hypertension, proteinuria and edema, occurring after 20 weeks of gestation in previously normotensive women, (Sunithaet al.,2012)
The aetiology of preeclampsia is yet unknown, however, it is associated with alteration in electrolyte status in pregnant women (electrolytes like sodium, potassium, chloride, bicarbonate etc). Hypertension is a universal problem and it complicates at least 10% of all pregnancies. Fluid and electrolyte abnormalities are common in critically ill patients of which preeclampsia patients are not excluded,(Indumati et al.,2011). Hypertension or high blood pressure occurs when the blood flowing through the artery walls move faster and harder than needed. This excess pressure unnecessarily pounds the blood vessels and can cause them to get weak. However, when too much sodium is ingested, it can cause the body to retain more water and fluid than is necessary. This hoarding of excess fluid or water by the body and its continuous movement through the body causes blood pressure to increase inside the blood vessel walls,(Carretero and Oparil, 2015).
Electrolyte imbalances have been in the spotlight of medical focus for quite sometime and this has to do with the fact that electrolytes play paramount roles in acid base balance, muscle function as well as serving as co-factors for enzymes. Abnormal electrolyte concentrations may be the cause of, or consequence of a variety of medical disorders, (Burtis and Burns, 2015).
Electrolytes are charged low-molecular-mass molecules that are present in plasma and cytosol; usually ions of sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate, sulfate and lactate,(Brutis and Bruns,2015).Electrolytes may be classified as anions, which are negatively charged ions that migrate towards the anode or as cations, which are positively charged ions that migrate towards the cathode, with the anode being the positive electrode and the cathode being the negative electrode, all in an electrochemical environment,(Indumati et al., 2011)
Among the physiologically important electrolytes, we shall focus on the four major electrolytes for the purpose of this study which include: Na+ ,K+, Cl–and HCO3– which occur primarily as free ions in contrast to Mg2+, Ca2+, trace elements which are bound by proteins, especially albumin,(Burtis and Burns, 2015). Our focus on the four major electrolytes (Na+ ,K+, Cl–and HCO3–) the purpose of this study, stems from the fact that the determination of body fluid concentration of these four major electrolytes is readily carried out in the medical laboratories as ‘electrolyte profile’ and are of high clinical significance,(Baha,2014).
The specimens which are typically assayed in the laboratory for their electrolyte content are mostly serum and plasma. Capillary blood is another sample commonly analysed. Heparinised whole blood arterial or venous specimens obtained for blood gases and pH determinations may also be used with direct ion-selective electrodes (ISES). The use of plasma or whole blood provides the advantage of shortening turnaround time because it is not necessary to wait for the blood to clot, (Manjareeka and Nanda,2012).
Furthermore, plasma or whole blood provides a distinct advantage in determining K+ concentrations which are invariably higher in serum depending on platelet count (Burtis and Burns, 2015).
Sodium is the major cation present in the extracellular fluid. About 40% of the body’s serum is contained in the bones. Approximately 2-5% occurs within body organs and cells and the remaining 55% is in blood plasma and other extracellular fluids. The amount of sodium in blood plasma is typically 140nM, a much higher amount than as found in intracellular sodium (about 5nM). This asymmetric distribution of sodium ions is essential for human life, (Banks,2010).
Sodium helps in the regulation of acid base balance as it readily combines with chloride (Cl–) or bicarbonate (HCO3–) to regulate the acid base balance. Sodium is also largely responsible for the osmolarity of vascular fluids. Doubling Na+ levels gives the approximate serum osmolarity. It is also involved in the regulation of body fluid, such that increased serum levels can cause water retention,(Banks,2010).It maintains blood pressure in the sense that while sodium shifts into the cells, potassium (another electrolyte) shifts out of the cells repeatedly to maintain water balance and neuromuscular activity,(Anuradha and Begum,2016)