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NORMAL ELECTROLYTE VALUES IN AN ADULT NIGERIAN POPULATION






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NORMAL ELECTROLYTE VALUES IN AN ADULT NIGERIAN POPULATION












ABSTRACT
Serum levels of sodium, potassium and chloride were determined in fifty Nigerian adults (thirty males and twenty females). Sodium and potassium was determined by flame photometry while chloride was determined by modified scales and scales method. The mean values were as follows: Sodium = 137.0 MEq/L, Potassium = 3.9 MEq/L, Chloride = 105.0 MEq/L. There were no significant ( ) differences on the values obtained with sex, nor was there any significant difference between values obtained for the different age groups. The results obtained in the present study compares favorably with result from similar studies carried out on Africans. Compared to non-Africans, the results from the present study are somewhat lower, and the possible causes are explained.















TABLE OF CONTENTS
Title Page -       -       -       -       -       -       -       -       -       -       i
Declaration      -       -       -       -       -       -       -       -       -       ii
Dedication       -       -       -       -       -       -       -       -       -       iii
Acknowledgement    -       -       -       -       -       -       -       -       iv
Abstract   -       -       -       -       -       -       -       -       -       -       v
Table of Contents     -       -       -       -       -       -       -       -       vi
List of Tables   -       -       -       -       -       -       -       -       -       vii
List of Figures  -       -       -       -       -       -       -       -       -       viii

CHAAPTER ONE:    INTRODUCTION AND LITERATURE REVIEW
1.1      Introduction
1.2      Regulation of E.C.F. Electrolyte
1.3      Law Concentrations
1.4      The Concept of Electrolyte Balance
1.5      The Concept of Determining the “Normal” Value
1.6      Literature Review

CHAPTER TWO:      MATERIALS AND METHODS
2.1   Study Area and Criteria
2.2   Collection of Blood Samples
2.3   Estimation of Electrolyte Concentration


CHAPTER THREE: RESULTS

3.1   Results
3.2   Determination of the Range for “Normal” Values
3.3   Effect of Sex on Electrolyte Distribution
3.4   Effect of Age on Electrolyte Distribution
3.5   Comparison of Results of Present Study with Result of Similar Studies



CHAPTER FOUR:    DISCUSSION AND REFERENCES
4.1   Discussion
        References
        Appendices
i.            Analysis of Electrolyte Values in a Nigerian Adult Population University of Port Harcourt, Choba and its Vicinity with Age, Sex, Mean Values and Standard Deviations.
ii.          Student’s t – Distribution Table


       










LIST OF TABLES
Table I:             Age and Sex Distribution of Subjects
Table II:            Mean Values, Range and Standard Deviation of the Electrolytes
Table III:           Normal Values for Serum Electrolytes at 95% Confidence Limit.
Table IV:          Mean Serum Sodium Levels for Different Age-Groups in Males and Females
Table V:           Mean Serum Potassium Levels for Different Age-Groups in Males and Females
Table VI:          Mean Serum Chloride Levels for Different Age-Groups in Males and Females
Table VII:         Mean Electrolyte Distribution According to Age Groups
Table VIII:        Mean Sodium Levels for Age Groups and for the Present Study
Table IX:          Mean Potassium Levels for Age Groups and for the Present Study
Table X:           Mean Chloride Levels for Age Groups and for the Present Study
Table XI:          Serum Electrolytes in Present Study Compared with Similar Studies of African Populations
Table XII:         Serum Electrolytes in Present Study Compared with Similar Studies of Non-African Populations.




LIST OF TABLES
Figure 1:       Effect of Blocking the Adh-Thirst Feedback System on Plasma Sodium Concentration
Figure 2:       Effect of Blocking the Aldosterone System on Plasma Sodium Concentration
Figure 3:       Effect of Blocking the Aldosterone System on Plasma Potassium Concentration
Figure 4:       Simple Bar Chart Representation of Mean Serum Sodium Level for the Different Age Group
Figure 5:       Simple Bar Chart Representation of Mean Potassium Level for the Different Age Group
Figure 6:       Simple Bar Chart Representation of Mean Chloride Level for the Different Age Group
Figure 7:       Multiple Bar Chart Representation of the Mean Serum Levels of Sodium, Potassium and Chloride for the Different Age Groups.







CHAPTER ONE
INTRODUCTION AND LITERATURE REVIEW
1.1      INTRODUCTION
The determination of serum/plasma levels of the various electrolytes in the body now constitutes a major and routine procedure in clinical chemistry laboratories, as well as being subject of increasing research interest. Clinical requests for electrolyte determination are based on the fact that a constant biochemical environment must be maintained by the body of healthy individuals to maintain a state of electrolyte equilibrium. Should the levels of plasma electrolytes be markedly altered from the normal, this condition indicates that there will be disturbance of certain physiological processes in the body, as well as shifts of electrolytes between compartments of body fluids. Thus in the ideal state, the total amount of electrolyte lost each day should be equal to the total amount gained; a state of electrolyte derangement arises if this equation does not occur.
The metabolism of body electrolytes, especially in developing countries, constitute an important aspect of physiological and clinical studies, but most of the data available to show the “normal” biochemical values of such electrolytes in these countries often to differ significantly from the values obtained is other developed countries.
This disparity has led to great interest in investigating what should be regarded as the normal values for these electrolytes in these developing and tropical countries, and comparing these values with what is accepted as normal in temperate countries.
 The electrolytes of the body are distributable into both the extracellular and the intracellular fluid compartments. In the cells, the most important electrolytes are potassium, mapnesium, phosphate, sulphate, bicarbonate and small quantities of sodium, chloride and calcium. These electrolytes are dissolved in the water of the protoplasm, providing inorganic chemicals for cellular reactions, as well as being essential in the operation of some the cellular control mechanisms including the determination of different enzymatically catalyzed reactions necessary for cellular metabolism and also facilitating the electrochemical transmission of impulses in nerve and muscle fibres.
In the extracellular compartment, however, the major electrolytes are sodium chloride, calcium and small quantities of potassium, magnesium phosphate etc. It is not easy to measure the concentration of intracellular electrolytes; this being possible only by indirect determination, but the composition of the ECF may be studied using the blood plasma obtained from subjects.
Some of the electrolytes are excreted in urine, and often this body fluid is used in assessing the quantity of the electrolytes in the body, but obviously it is an imperfect method because since the amount secreted will vary widely within individuals and even within the same subject. The reason is that there are many variables controlling the amount of electrolytes excreted at any particular time.
1.2      REGULATION OF ECF ELECTROLYTE CONCS.
The extracellular fluid sodium concentration determines the osmolality of the ECF as well as ICF (both being in Osmotic equilibrium) since sodium is by far the most abundant cation in the ECF. Also the acid-base control mechanism adjusts the anion concentrations of the body fluids to equal those of the cation. Sodium exerts this Osmolar effect through two control systems:
i.            Osmo-sodium receptor (osmo-receptors) – Anticliuretic Hormone Feedback Control Mechanism.
In this mechanism, increased osmolality excites the osmo-receptor located in the supraoptic nucleus causing release of antidiuretic hormone. This hormone increases the permeability of the collecting waters reabsorption, which leads to increased water retention without concomitant increased sodium retention. This corrects the initial high osmolality of the ECF. Conversely, if the ECF is hypo-osmotic, less ADH is produced leading to increased loss of water thus concentrating the body fluid back to normal.
ii.          Thirst
This is based on the balanced intake and output of water each day. Conscious desire for water is generated in a small area in the lateral periotic area of the hypothalamus called the thirst center is intracellular dehydration, caused by high osmolar ECF drawing water from the thirst center which causes sensation of thirst, leading to increased water drinking thus tending to read just the osmolality towards normal. It would appear that the combined role of ADH-Thirst mechanisms regulates sodium concentration in the body.
40               80           120                   160                         200
Plasma Sodium Concentration MEq/L
152  



148  



144  



140   



136


Normal
0
Sodium Intake (MEq/Day)
Figure 1: The Effect of Blocking the ADH-Thirst Feedback System on Plasma Sodium Concentration.
                                                        ADH-Thirst System
                                                             Blocked

                                                                            



        In addition, aldosterone and other mineralocorticoids are known to play a small role in the control of extracellular sodium concentration. By far the most import effect is to increase the rate of tubular reabsorption of sodium. By micro-puncture techniques, it has shown that aldosterone has an especially potent effect in increasing sodium reabsorption all along the renal tubule. Thus an increased aldosterone level in the body tends to decrease the daily loss of sodium in the urine.
        Although the effect of increased aldosterone is to increase the quantity of sodium in the extracellular fluids, significant hypernatremia does not usually occur because the subject become extremely thirsty and keep adding more water to his body fluid thus diluting the sodium concentration appreciably and thereby maintaining almost normal. Thus aldosterone is regarded as only playing but a minor role in controlling extracellular fluid sodium concentration. It is thus paradoxically that aldosterone should cause sodium retention and at the same time maintain the sodium concentration.

40               80           120                   160                         200
Plasma Sodium Concentration MEq/L
150  



140  



130  



120   



110

100
Normal
0
Sodium Intake (MEq/Day)
    Aldosterone
System Blocked

Figure 2: Effect of Blocking the Aldosterone System on Plasma Sodium Concentration.  






                                        







        This increased reabsorption of sodium also causes hydrogen ions to be secreted into the tubules and lost in urine, leading to alkalosis. This change in body pH is not excessive however, and ordinarily can be adequately compensated by the normal acid-base regulatory mechanisms.
        Aldosterone mechanism plays a very powerful role in the control of extracellular potassium by enhancing its secretion into the distal tubeless and collecting tubules of the kidney. This is caused mainly by the extreme electronegativity created in the tubules by the exit of sodium ions. Thus large amounts of potassium are excreted from the body fluid through urine.
40               80           120                   160                         200
Plasma Potassium Concentration MEq/L
   4.8  



   4.6  



   4.4  



   4.2   


   4.0


Normal
Potassium Intake (MEq/Day)









Figure 3: Effect of Blocking the Aldosterone System on Plasma Potassium Concentration

                               Aldosterone System
                                                                  Blocked










In primary aldosteronism, caused by tunour of the glomerulosa of one of the adrenal glands, the excessive aldosterone secreted results in severe decrease in the extracellular fluid potassium concentration that the patient experiences paralysis caused by failure of nerve transmission of impulses, resulting from hyperpolarization of the nerve membranes. Conversely in addition disease the potassium level is so high that it can frequently cause cardiac death resulting from cardiac arrhythmias that can lead to cardiac fibrillation.
Aldosterone also causes a greatly enhanced reabsorption of anions especially chloride ions. The reason is exactly the opposite to the effects on potassium and hydrogen ions. The chloride ions are repelled from the electronegative tubular fluid and are attracted towards the extracellular fluid. In this way, the total quantity of sodium chloride in the body fluid increase under the stimulus of aldosterone.
Loss of adrenocortical secretion usually causes death within two weeks unless the patient receives adequate salt or mineralocorticoid therapy. Without this, the potassium and hydrogen ion concentration in the extracellular fluid becomes markedly high, the sodium and chloride concentration decrease and the total extracellular fluid volume and blood volume also become greatly reduced.
1.3      LAW OF ELECTRO-NEUTRALITY
An important law of electrolyte solutions is the “Law of Electro-neutrality” which requires that the sum of positive charges on the cations in any solution must be equal to the som of the negative charges on the anions. One consequence of this principle is that methods for determining the total concentrations of the metallic cations (Na+, K+, Ca++ and Mg++) in the plasma, do in fact measure the total concentration of base, only they do so indirectly by estimating the cations whose total concentrations must be the same. Moreso, as Barker and Elkinton (1958) pointed out the concept of “buffer base” which Singer and Hastings (1948) proposed to describe the acid-base status of the blood becomes even more valuable if the “buffer base” is regarded as the total concentration of buffer anions, rather than as the concentration of the unspecified cations which balance their negative charges.
In human, the major electrolytes in the plasma are Sodium (Na+), Potassium (K+), Chloride (Cl-), Bicarbonate (HC03) and Protein (Pr-). If the concentrations of these ions are measured, the principle of Ionic Equality requires that the concentration of the cations should match that of the anions. Any deviation from this state of ionic equality results in a chain of events aimed at returning the state of this body to electro-neutrality but this may result in widespread loss of electrolytes. By selectively excreting excess ingested inorganic ions which are surplus to the body and maximally retaining deficient ions, the kidney maintains the body in electrolyte balance.
Sodium is the principal cation of the Extracellular Fluid (ECF) compartment whereas potassium predominates in the Intracellular Fluid (I.C.F.). Conversely, in the ECF, potassium is only little, just as is sodium in I.C.F. while chloride is an important anion in ECF, phosphate and sulphate are found mainly in the cells.
These differences between ECF and ICF are extremely important to the life of the cell. The differences by ionic composition between I.C.F and E.C.F depend on two main mechanisms: the inability of large molecules to pass freely across the cell membranes and the Active Transport of substances across the cell membranes. These various transport mechanism e.g. the sodium – potassium pump, require the expenditure of energy. Thus the integrity of the cell membrane and a sufficient supply of energy determine the differences and changes in composition between the two compartments is Osmosis of water, resulting from differing osmolality of the two compartments. In this, fluid mainly water, move from one compartment of low osmolality to the other of higher osmolality in a bid to bring the two compartments to the same osmolality.
The total amount of sodium and potassium in the body may be estimated by chemical analysis of cadavers. It may also be estimated by dilution techniques with radioactive isotopes  and . Since the latter isotope occurs naturally as a constant proportion of the total potassium, the body potassium may be estimated by total body scanning of the isotope. The estimation of total body sodium by dilution technique gives a figure 17% lower than that obtained by chemical analysis because only one third of the total amount of sodium is immediately exchangeable. The other is fixed in bones and has a long turnover time.
The determination of Na and K levels in plasma has nowadays been made simple and a routine clinical procedure with the advent of flame emission spectrophotometry. Plasma is separated from the blood cells as soon as possible after collection of the blood sample. The plasma is diluted with lithium nitrate and the solution is sprayed into a flame. The resultant increases in the yellow colour due to Na and violet colour due to potassium are compared with the constant emission in the red part of the spectrum given by the lithium. All electrolytes are obtained from diet, principally food, though drinking water may supply small amounts of some ions. Losses of electrolytes in a temperate climate are in faces, sweat and in urine.
Water can be removed from the body by evaporation from the skin, evaporation from the lungs, excretion of vey dilute urine or, in cases of severe water loss and electrolyte derangement which follow diarrhea and vomiting. In all these conditions, water leaves the extracellular fluid compartment, but on doing so some of the intracellular water pass immediately into the extracellular compartment by osmosis in an attempt to keep the osmolality’s of both compartments equal. The overall effect is called dehydration, an intravenous infusion of the appropriate solutions is normally required, and for effective rehydration, an accurate knowledge of normal electrolyte volumes is of extreme importance.
If an isotonic solution is added to the extracellular fluid compartment, the osmolality of the extracellular fluid does not change, on osmosis occurs and the only effect is an increased extracellular fluid volume. However if a hypertonic solution is added, the osmolality of the internal environment (extracellular fluid) increases and causes osmosis of water out of the intracellular fluid compartment to the extracellular compartment. If, on the other hand, a hypotonic solution is added, the osmolality of the extracellular fluid decreases and fluid pass into the cells.
On this principle, very concentrated glucose, manitol or a sucrose solution are often administered into patients to cause immediate decrease in intracellular fluid volume. This principle is used, for example, in severe cerebral oedema, where the patient could die of too much pressure in cranial vault, which obstructs the flow of blood to the brain. This procedure is of temporary benefit because the substances are either soon excreted or metabolized, but within the two to four hours of its osmotic activity, the lift of a dying patient could be saved.
1.4   THE CONCEPT ELECTROLYTE (CATI0N-ANION) BALANCE
        Combined functions of the buffer system of blood, respiratory system and renal mechanism are of great importance in maintaining the normal composition cations and anions of the body to maintain electrical neutrality. This electrical neutrality is maintained at all times – increase in one anion is accompanied by a corresponding decrease in some other anion or by an increase in cation, so that the neutrality is hardly altered.
Plasma has a volume of 1300 – 1800 ml/sq.m of body surface and constitutes 5% of the body weight. Until now, it was not possible to explain the unequal distribution of most electrolytes between ICF and ECF in terms of physic – chemical theories of diffusion. The Gibbs – Donnan Equilibrium has successfully explained the unequal distribution of chloride and bicarbonate between red cells and the plasma. Van Slyke et al (1923) has shown that higher chloride and bicarbonate content of plasma is due to the presence of the negatively charged non-diffusible hemoglobin inside the red cell, in accordance with the Gibbs – Dannan Equilibrium.
        The bicarbonate buffer system regulates the pH of the body. If the body level of hydrogen ions ( ) is high, more bicarbonate  converts to hydrogen bicarbonate  :-
                 +    HH
If the add base
        H H  +      + 0
In this way the pH of the body is adequately buffered. Of clinical interest in connection with regulation of body pH are the pH of plasma and erythrocytes.
i.            Sodium Balance
Sodium is the major cation of E.C.F and occupies central role in maintenance of normal hydration and osmotic pressure. Normal daily diet has about 130 – 250 m Eq(8 -15 gm) of sodium chloride (NaCl) most of which is completely reabsorbed in the gastrointestinal tract. Excess of these is secreted by the kidney which is the ultimate regulator of sodium content in the body. Sodium is a threshold substance with a normal threshold of 110 – 130 mEq/L. Below this threshold, all sodium present in the glomerular filtrate is reabsorbed in the renal tubule. The reabsorption is greatly affected by adrenal cortical hormones, mainly aldosterone which enhances the tubular reabsorption of sodium as well as chloride but decreases that of potassium. The exchange of Na+ for H+ is an important mechanism of the acidification of urine.
Hypernatremia is found is found in a variety of conditions including the following:
i.            Extreme urine loss, as in diabetes insipidus
ii.          Metabolic acidosis e.g. diabetic acidosis in which the ions are excreted along with the urine.
iii.        Addison’s disease, in which there may be a decrease secretion of corticosteroids, mainly aldosterone, causes decreased reabsorption of sodium by renal tubules and thus loss of serum sodium.
iv.         Diarrhea, in which an excessive amount of sodium is lost through the stool.
v.           Renal tubular disease, in which there may be a defect in either the reabsorption of sodium or the Na+ - H+ exchange. Hypernatremia is found in the following conditions:
i.            Hyperadrenalism (Cushing’s syndrome) in which increase production of corticosteroids causes increased sodium reabsorption and retention.
ii.          Severe dehydration due to primary water loss.
iii.        Certain types of brain injury.
iv.         Diabetic coma after insulin therapy, believed to be due to a retransfer of cellular sodium into the extracellular fluid in order to maintain equal osmotic pressure in both compartments
v.           Excessive treatment with or ingestion of sodium salts and drugs.
Normal values
Range of normal values for serum sodium is 135 – 148 MEq/L urinary sodium excretion vary considerably and show diurnal variations.
ii      Body Potassium
        Potassium is the major intracellular cation. The level in tissue cells is about 150m Eq/L and about 105mEq/L in red blood cells – about 23 times more than that in the extracellular fluid. This concentration difference is maintained by active transport mechanisms and relatively low permeability of K+ through the cells.
        However there are some movements of K+ across the cells and this may occur if the serum is not separated from the cells shortly after collection.
        Unlike sodium and chloride, there is no threshold level for K+, thus it is effectively re-excreted by the distal tubules. Any K+ reabsorption in the gastrointestinal tract causes only a slight and temporary rise in serum level; a fraction of these moves into the I.C.F and the remainder is rapidly excreted by the kidney.
        This mechanism protects the body against high serum  levels which could cause serious (inhibitory) disturbances in muscle irritability, respiration and myocardial function as well as characteristic E.C.G. changes. Such symptoms appear with levels of above 7.5mEq/L; a 10mEq/L level may be fatal
        Low  levels cause excitatory changes in muscle irritability and myocardial function, which are also accompanied by characteristic E.C.G. changes. For these reasons, serum  determination has become a most important diagnostic tool.
        The mechanism of  excretion and absence of threshold level has the disadvantage that the body has no effective mechanism to prevent excessive loss, because even in deficiency, kidney continues to excrete potassium. Thus regular intake of  in diet or in drug us essential.
        Hypokalemia may result from inadequate intake,  loss via prolonged diarrhea or through vomitus. Also increased corticosteroids result in reduced potassium level by causing increased loss. Alkalosis causes movement of  into the cells in exchange of , and the reverse is the case in acidosis. Thus alkalosis can result in reduced serum potassium level. In fact low intracellular  can lead to alkalosis.
        Hyperkalemia is generally observed in cases of oliguria, anuria or urinary obstruction. In renal failure one of the important purposes of renal dialysis is the removal of accumulated potassium from the plasma.
        Specimen for use for potassium level determination should be free from hemolysis. Blood serum should be separated shortly after collection. The shift of  is greater at refrigerator temperatures.
Normal Values:
        Serum value is 3.5 – 5.3mEq/L but higher in newborns (4.0 – 5.9). This may be due to error in collection and banding or it may be due to the accumulated store of potassium existing prepartum. Urine level is variable depending on diet and state of the body physiology.



iii     Body Chloride
        This is the major extracellular anion. It is significantly involved in maintaining proper hydration. Osmotic pressure and normal cation – anion balance in this compartment.
        Chloride ions are completely absorbed by gastrointestinal tract and are removed from the blood by glomerular filtration, then reabsorbed passively by the tubules. It may be lost through excessive sweating during hot periods. Low serum chloride values are observed in salt-losing chromic pyelonephritis. This loss is due to a lack of tubular reabsorption despite body deficit of chloride. In addisionian crisis, chloride (and sodium) levels may drop significantly. Low chloride levels may also occur in those types of metabolic acidosis (e.g. diabetic acidosis and renal failure) caused by excessive production or diminished excretion of acids. Prolonged vomiting may also result in significant loss of chloride.
        High serum  values are obtained in dehydration and in conditions causing decreased renal blood flow e.g. congestive heart failure. Hypercloremic acidosis may be a sign of severe renal tubular pathology.
1.5   THE CONCEPT OF DETERMINING THE “NORMAL” VALUE
        The question of normal electrolyte values constituting electrolyte balance is still on heated debate as to the proper definition of “Normalcy” or “Normalness” of the values obtained or used.
        It is now the contention that ‘normal’ is used not necessarily for person without any physical ailment, because this would rule out virtually all persons of 20 years of age and above (Pryce, 1970, 1964). ‘Normal’ is used to connote the person who is not suffering from any disease or disability likely to directly or indirectly affect the results of the parameters under investigation.
        A normal value for a given constituent or clinical interest is considered to be that of the constituent of interest which is found in the body fluid or excretion of a group of clinically normal (apparently healthy) persons. These normal values are arbitrarily defined as the range of values that would encompass 95% of a population of these clinically normal persons. These normal data may be different from the ideal or physiologically desirably value.
        When establishing normal values for chemical constituents of body fluids and excretions, physiologic variations are taken into consideration, which may include diurnal variations, true day-to-day variation and the environment. Also differences due to race, age, sex, weight, nutritional and absorptive states, degree of physical activity, position of body during blood sampling, stage of menstrual cycle, ovarian status, emotional state, flexographic location and time of day at which sample was taken.
Establishment of Normal Values:
        This is necessary when a new method has been developed or if the laboratory wishes to compare its range of normal values with that found in literature.
        In practice it is necessary to analyze the blood of a group of apparently healthy individuals. Values thus obtained have to be treated in a way that will result in a meaningful normal range. The procedure to be selected will depend on the number of data available on the type of data obtained and their relative distribution.
        In practice, it is usual to consider about 100 data, but frequently such number is not available and consequently, the type of statistical method applied have to be selected accordingly. Data distributed according to a symmetrical bell-shaped pattern is treated differently from that skewed to one direction.
        For most constituents, there may be an overlap of values for normal and abnormal populations if the normal range is set in such a way that it would include the entire normal population. Some of the abnormal values would be in the normal range and go undetected. On the other hand, a narrower normal range is used; a number of normal subjects may have an ‘abnormal’ laboratory result. In the first case, a disease state may be over looked and considered as a normal value just because it falls within the normal range. In the second case where the range is too narrow, a normal subject may be adjudged erroneously to show an abnormal value because the value falls outside the fixed range. Thus a compromise has to be achieved to ensure that the error made either way is minimal.

1.7      LITERATURE REVIEW
It has been reported that Africans have smaller adrenal cortices with cortical hypo-function as compared to Europeans Barnicot et al 1952; Monnet et al, 1952; Politzer et al, 1958; Trowel 1960 and Edozien, 1960. However, only very little work has been done to assess the implication of this hypo-function on their plasma cation composition, and the results are conflicting.
Leschi (1952) in Dakar in a comparative study of plasma cation content of Africans and Europeans reported that the mean level of Na was about 5% lower in Africans. This view was supported by Politzer (1954) in South Africa who reported the South African Bantu Miner workers as having mean Plasma sodium of 137meq/l (range 132-142) which would be regarded as low.
But Owor (1965) in Uganda reported plasma Na values in Africans quire similar to the European text-book values (mean 141 meq/1; range = 134 to 147 meq/1); and so did Edozien (1958) in Nigeria. However, Adedavoh (1970) (personal communication – quoted by Ezeilo, 1972) later reported from the same laboratory as Edozien, a lower range for Nigerians (120 – 140meq/liters).
Also more recently, Ezeilo 1972 reports that there are no significant differences between the plasma or cellular values of sodium and potassium in normal adults of the two races. 
Not much work has aslo been done on the plasma cation composition of pregnant Africans women. The fact that African women fail to gain weight as much as European women (Watts, 1970) could point to a failure to accumulate sodium during pregnancy in Africans. In fact, Ezeilo (1972) found that in pregnant African women, there was a hyponatremia relative to normal adults, which might be contributory for their failure of gaining weight as much as their European counterparts.
Reports in Nigerian adults (Edozien 1958) and in Nigerian adults and children combined (McFarlane et al 1970) are conflicting. The latter report concerned a large population of blood donors, student nurses, pregnant women and random selection of patients with unspecified diagnoses, including children. It is probable that most of the subjects used, excepting maybe the student nurses and blood donors, were not normal subjects. Pregnancy state is known to be associated with hypervolaenia, and many hospital patients suffer from diarrhea and some degree of dehydration. These differences in the subjects studied may be the cause of conflict in the reports in Nigerian adults (Edozien 1958) and combined Nigerian adults and children (McFarlane et al. 1970).
Whereas Edozien reports a plasma Na level similar to that of Europeans (136-150 range), McFarlane et al reports a range of 119-140 a lower range.
Effiong et al (1974) also did a study of serum electrolyte and urea in healthy Nigerian children. They report that “generally, serum electrolytes levels were significantly higher than the levels reported in Nigerians and lower than those for North American children”. The range for serum sodium (130-148 Eq/1) in their study compares favorably with the British range of 136-145 mEq/1 (Birmingham children Hospital Vade-vecum 1970). They also failed to confirm the finding of McFarlane et al (1970) who reported higher mean serum sodium levels in males than in females. Effiong et al. 1974 also found that the chloride values were significantly lower than the values reported from North America but smilar, however, to that for British children, McFarlane et al 1970 and Stone 1936 have reported a low chloride level in Nigerians and South Rhodesian Africans respectively. Politzer, Barry and King (1954) also reported higher values in South African Bantus, whereas Edozien (1958) reports the value of chloride in Nigerians as similar to that of the Caucasians.
Also Effiong et al (1974) concludes that the bicarbonate level are significantly lower than that reported by Gottfried et al (1954).    






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