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). Inheritance of sickle cell disease predisposes to four main types of crises: vaso-occlusive, splenic sequestration, aplastic and hemolytic. The morbidity and mortality from these events may be manifested as pain, acute chest syndrome (intrapulmonary sickling), pulmonary hypertension, cardiac abnormalities, cerebrovascular hemorrhage/infarct, splenic or hepatic sequestration, autosplenism, renal disease, liver disease, avascular necrosis of the femoral head, priapism, and life-threatening acute hemolytic or aplastic anemia. Triggers for an acute crisis include hypoxemia, dehydration, acidosis, stress, infection, trauma, hypothermia or in some cases, no identifiable predisposing risk factors (Aldrich and Nagel, 2008).
Electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. The balance of electrolytes in the body is essential for the normal functioning of the cells and organs. Electrolytes measured by blood testing includes sodium (Na+), Potassium (K+), Chloride (Cl-) and bicarbonate (HCO3-). Electrolytes have normal range values, and complications may arise, if any of the electrolytes are higher or lower than the normal range values. Sodium (Na+) is the major positive ion (cation) in the fluid outside of the cells. In combination with chloride, it forms a salt (NaCl). Sodium (Na+) regulates the amount of total body water and plays a critical role in electrical communication especially in the brain, nervous systems and muscles.
Biochemical abnormalities have been associated with sickle cell disease; however there is paucity of information on the roles of these ions in the pathogenesis and management of sickle cell disease (Oladipo et al., 2005). In sickle cells, an abnormal activation of potassium chloride (K+Cl-) co-transport system was proposed to be involved in cell potassium (K+) loss and dehydration (Vitoux et al., 1989). Deoxygenation of sickle cell is known to increase cation permeability of sodium (Na+), Potassium (K+) and calcium (Ca2+) (Rhoda et al., 1990), At lower Hydrogen ion concentration (pH), urea was able to stimulate potassium – chloride (K-Cl-) loss from sickle cells, leading to cellular dehydration, even in regions of low pulmonary oxygen tension (PO2). Potassium – Chloride (K+ Cl-) co-transport is abnormally active in erythrocytes containing positive charged haemoglobins such as haemoglobin (S) (HbS) On deoxygenation, haemoglobin(S) (HbS) cells exhibit a distinctive solute permeability pathway, P sickle, activated stochastically and partially inhibited by 4,4- disothiocyano 2 – 2 disulfostibene (DIDS) and dipyridamole. It is often referred to as a cation channel although its permeability characteristics remains vague and it molecular identity is unknown (Browning et al., 2007).
Sickle cell disease is a public health problem and accounts for a lot of morbidity and mortality in the society. Sickle cell disease is much more prevalent in Africa
and Mediterranean crescent. Although the effects of sickle cell disease (SCD) on general morbidity and mortality have been studied but not much work has been done on the comparative study of the electrolyte pattern in sickle cell disease patients. There is therefore the need to bridge this gap. Therefore this work is done to justify the electrolyte pattern in sickle cell patient in Owerri metropolis.
1.2 AIMS AND OBJECTIVE
(1) To determine the level of the sodium, potassium, bicarbonate and chloride electrolyte in patients with sickle cell disease.
(2) To compare the sodium, potassium, bicarbonate and chloride electrolyte level of patients with sickle cell disease with those of normal individuals.