Serum Sodium Concentration In Sickle Cell Patient

Introduction

1.1 Background to the Study

Sickle cell disease (SCD) is a group of inherited disorders of the beta-hemoglobin chain. Normal hemoglobin has 3 different types of hemoglobin – hemoglobin A, A2, and F. Hemoglobin S in sickle cell disease contains an abnormal beta globin chain encoded by a substitution of valine for glutamic acid on chromosome 11 (Bunn,2007). This is an autosomal recessive disorder. Sickle cell disease refers to a specific genotype in which a person inherits one copy of the HbS gene and another gene coding for a qualitatively or quantitatively abnormal beta globin chain. Sickle cell anemia (HbSS) refers to patients who are homozygous for the HbS gene, while heterozygous forms may pair HbS with genes coding for other types of abnormal hemoglobin such as hemoglobin C, an autosomal recessive mutation which substitutes lysine for glutamic acid. In addition, persons can inherit a combination of HbS and β-thalassemia. The β-thalassemias represent an autosomal recessive disorder with reduced production or absence of β-globin chains resulting in anemia. Other genotype pairs include HbSD, HbSO-Arab and HbSE (Meremiku, 2008).

Sickle hemoglobin in these disorders cause affected red blood cells to polymerize under conditions of low oxygen tension resulting in the characteristic sickle shape. Normal red cells live about 120 days in the blood stream but sickled red cells die after about 10 – 20 days. Because they cannot be replaced fast enough, the blood is chronically short of red blood cells, a condition called anaemia. Aggregation of sickle cells in the microcirculation from inflammation, endothelial abnormalities, and thrombophilia lead to ischemia in end organs and tissues distal to the blockage (Hayes, 2004).

Sickle cell disease (SCD) is a group of haemoglobinopathies characterized by the inheritance of two abnormal haemoglobin genes in which at least one is the Haemoglobin S gene. The synthesis of Haemoglobin S is a result of a point mutation in the beta-globin gene resulting in the substitution of glutamic acid for valine in the beta-globin protein. Homozygous form of the SCD, which is commonly termed as sickle cell anaemia, is a combination of two forms of the Haemoglobin S genes, while a combination of another variant haemoglobin gene (HbC) with the Haemoglobin S gives the heterozygous form. About 20 million people are affected by the disease worldwide, with a high prevalence, especially of the homozygous form, living in Africa.1

Sickling, which is associated with Haemoglobin S and erythrocyte haemolysis, affects the overall electrolyte balance in sickle cell patients and may lead to increased cell dehydration.2,3 Electrolytes such as sodium (Na+) plays a vital role in the body and are required for optimal functioning of cells and organs. Sodium is one of the major cations and functions in regulating the total amount of water in the body. It also plays a vital role in electrical communication in many systems especially the nervous and muscular systems. However, potassium is responsible for regulating heartbeat and muscle function and is important for the overall functioning of the cell. Chloride helps maintain a normal balance of body fluids. Alteration of these electrolytes could, thus, lead to detrimental effects.

In SCD, commonly encountered events, such as intravenous potassium administration and blood transfusion, can lead to increased serum potassium level and can also affect the levels of other electrolytes.4,5 This may consequently put SCD patients at risk of experiencing fatal outcomes including episodes of vaso-occlusion. Abnormal activation of the potassium chloride (K+-Cl−) co-transport system and the Gardos channel has been proposed to be involved in intra-erythrocytic shift of potassium.6

In most cases, the deoxygenation of sickle cell promotes cation permeability of electrolytes including potassium and calcium.3 These processes may consequently lead to increased cell dehydration in the sickle cell patients, with aggravated clinical complications. Previous studies have been conducted mainly to determine the levels of electrolytes in patients with sickle cell anaemia (HbSS),7-10 as well as other sickle cell genotypes other than HbSC.11 In Nigeria, no single study has been done to determine and to compare the relative levels of electrolytes in patients with HbSS and HbSC genotypes. In most cases, clinical characteristics are inferred from studies involving only HbSS. Meanwhile, the clinical presentations of these two genotypes (HbSS and HbSC) have been shown to be different,12 with the latter being less severe. In this study, serum levels of some major electrolytes were determined in sickle cell patients (HbSS and HbSC genotypes) and compared with ‘healthy’ controls in Nigeria.

Sickle cell disease is a group of haemoglobin disorders in which the sickle beta (β) globin gene is inherited (Hoffbrand et al., 2006). Sickle cell disease affects millions of people worldwide, which poses significant challenges for clinicians and scientists as one of the most commonly observed haemoglobinopathies.

There are excellent treatments for the symptoms and complications of the condition, but in most cases there is no cure. Some researchers believe that bone marrow transplant may offer a cure in a small number of cases (Harvey, 2002).

The clinical manifestation of sickle cell anaemia in India seems to be milder than in Africa and Jamaica (Mohanty et al., 2002). In Africa few children with sickle anaemia survive to adult life without medical attention. Even with standard medical care approximately 15% die by the age of 20 years and 50% by the age of 40 years (Boon et al., 2006). Harvey (2002) reported that sickle cell gene for haemoglobin(s) Hb(s) is the most common inherited blood condition in America, about 72,000 disease.

1.2 Objectives of the Study

The objective of this study is to examine the concentration of serum sodium in sickle cell patients.

1.3 Significance of the Study

This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.

1.4 Scope of the Study

This study is on serum sodium concentration in sickle cell patient.

1.5 Limitations of the study

The demanding schedule of combining school work with this research made it very difficult getting the specimen needed for this study. As a result, retrieving the specimen in timely fashion was very challenging. Also, the researcher is a student and therefore has limited time as well as resources in covering extensive literature available in conducting this research. Information provided by the researcher may not hold true for all experiments but is restricted to experiment carried out during the cause of this research.

1.6 Definition of Terms

Sickle Cell:

Sickle cell disease is a group of disorders that affects hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this disorder have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle, or crescent, shape.

Patient:

A patient is any recipient of health care services. The patient is most often ill or injured and in need of treatment by a physician, nurse, psychologist, dentist, veterinarian, or other health care provider.