When healthy, the kidney removes waste products and fluids from the blood stream and excreting them in the urine, also the kidneys maintain the body's internal equilibrium of water and minerals (sodium, potassium, chloride, calcium, phosphorus, magnesium and sulfate) [ 1]. Renal failure is a situation in which kidney fails to function adequately [ 2]. Chronic renal failure (CRF) is a syndrome characterized by progressive and irreversible deterioration of renal function due to slow destruction of renal parenchyma [ 3]. Symptoms develop slowly, diagnosis is based on laboratory testing of renal function, sometimes followed by renal biopsy [ 4]. Acidosis is the major problem in CRF with development of biochemical azotemia and clinical uremia syndrome [ 3]. Prolonged decline in the ability of the kidney to regulate acid–base balance, eliminate waste products, and manage water homeostasis and entered chronic phase, toxic metabolic accumulates and erythropoietin secretion by the kidney is decreasing and causes hematological changes include decrease of HCT, MCV, RBCs, and platelet counts [ 5]. Treatment is primary directed at the underlying condition but includes fluid and electrolyte management and after hemodialysis, peritoneal dialysis, or transplantation [ 2,4]. The CRF refers to decline in the GFR caused by a variety of disease, such as diabetes, glomerulonephritis, hypertensive nephropathy, congenital and hereditary diseases [ 6], and polycystic kidney disease [ 6,7].

Dialysis is a procedure that removes excess fluids and toxic end products of metabolism such as urea from the plasma and corrects electrolytes balance by dialyzing the patient's blood against fluid containing no urea but has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood [ 8]. It may be used for those with an acute disturbance in kidney function or for those with progressive but chemically worsening kidney function a state know as chronic renal failure (CRF) [ 9]. Hemodialysis became a practical treatment for kidney failure and is the most common method used to treat advanced and permanent kidney failure [ 10].

End stage kidney disease (ESKD) is a major public health problem in Libya with diabetic kidney disease and chronic glomerulonephritis being the leading causes. The most frequent co-morbidities were hypertension, obesity and the metabolic syndrome [ 11]. The total number of patients with ESKD in the Middle East is almost 100 000, the mean prevalence being 430 per million population [ 12]. In 2003, the reported incidence of ESKD and prevalence of dialysis-treated ESKD in Libya were the same at 200 per million population (pmp). In 2007, the prevalence of dialysis-treated ESKD was 350 pmp, but the true incidence of ESKD was not available. The most recent published WHO data in 2012 showed the incidence of dialysis-treated ESKD had risen to 282 pmp and the prevalence of dialysis-treated ESKD had reached 624 pmp [ 11]. Between 2007 and 2009, the number of patients on dialysis in Libya increased from 2116 to 2417. It is projected that the number of patients on dialysis will increase from 2417 in 2009 to 7667 in 2024 [ 6]. To maintain a patient to dialysis machine ratio of 1: 3.4, the number of dialysis machines will need to grow from 1045 in 2014 to 2255 in 2024. The required number of general nephrology beds in 2014 is estimated around 468, with 59 additional regional transplant beds. These numbers are expected to be around 547 and 69 respectively by 2024 [ 6].

Anemia is a condition in which the number of RBCs (and consequently their oxygen carrying capacity) is insufficient to meet the body&#x02019;s physiologic needs [ 13]. It is one of the most common complications in hemodialysis patients [ 14]. The severity of anemia is related to the stage of kidney disease affecting nearly all patients with stage 5 CKD [ 15], and the deficiency or reduction in erythropoietin production which is the main cause. Also, inflammation, hyperparathyroidism, deficiency of folic acid, iron, and vitamin B₁₂, hemolysis, and blood loss are causes of anemia in among chronic kidney diseases patients [ 16,17]. Anemia causes fatigue, reduced exercise capacity, reduced libido, and cognitive function, which ultimately have a negative impact on their quality of life [ 18,19]. Anemia in CKD is associated with deprived general health, manifested as dizziness, fatigue, shortness of breath, reduced quality of life and exercise capacity, when Hb<10 g/dl [ 20]. In addition to being related to CVDs, heart failure are the leading causes of mortality in CKD [ 21]. Anemia in CKD is associated with cognitive impairment, sleep disturbances, CKD progression, cardiovascular comorbidities, and higher mortality [ 22,23].

Most of the previous literatures studied the prevalence of anemia among hemodialysis patients among anemic patients were in other countries but, to our knowledge, the evidences reporting it in our country are very few. So, for this reason, we carried out the current study.

The current study aimed to evaluate the prevalence of anemia among hemodialysis patients and investigate the variations of hematological parameters among anemic hemodialysis patients in the Tripoli region.

The present study was conducted on 250 renal failure patients, attending Tripoli Center for dialysis and 100 normal healthy subjects. The study design was reviewed and approved by the Ethical Committee of the medical centers and the Libyan Academy of graduate studies. Ethical approval and patient consent statements were taken from every patient. Personal information's regarding hemodialysis were collected through face-to-face interviews, using a structured questionnaire. Demographic and anthropometric data were included file number, gender, age, and duration of dialysis.

A blood sample of 5 ml was drawn by venous puncture from each normal healthy individual and hemodialysis patient. 2.5 ml of the blood sample was collected in K-EDTA tubes for the hematological examinations and another 2.5 ml of the blood sample was collected in plain tubes for biochemical tests (serum urea, creatinine, and uric acid).

The blood samples of all the study subjects were sent to the hospital laboratory for estimation of CBC and concentrations of serum urea, creatinine, and uric acid.

The complete blood count (RBCs count, Hb, HCT, MCV, MCH, MCHC, WBCs count, differential count of WBCs, and Platelets count) were determined using an automated hematology analyzer Sysmex (K- 4500) machine.

According to the World Health Organization [ 24] criteria for anemia in men is Hb<13 gm/dL and women is Hb<12 gm/dL. The degrees of anemia were mild, moderate, and severe in male>14 years, when hemoglobin concentrations were (11&#x02013;12.9), (8&#x02013;10.9), and <8g/dL and in female>14 years, when hemoglobin concentrations were (11&#x02013;11.9), (8&#x02013;10.9), and <8 g/dL, respectively [ 25].

2.5 ml of the blood sample was collected in a plain tubes for estimation of serum urea, creatinine, and uric acid concentrations. After clotting of blood in the plain vial, serum was separated, within an hour; by centrifugation at 3000 - 5000 g for 5 min. Serum was used for measurements of the levels of serum urea, creatinine, and uric acid. Biochemical studies were performed using commercially available kits from Biomeriux (France), and serum parameters were quantified according to the manufacturer&#x02019;s instructions.

The data of blood parameters of both healthy individuals and hemodialysis patients were performed on a computer excel sheath and captured from excel for further analysis on GraphPad Prism 9.0 software. The Kolmogorov-Smirnov test was used to assess the normality of distribution of continuous variables. The statistical significance of differences between groups was evaluated with the independent t-test. A P-value of <0.05 was considered significant for all statistical test.

Table 1 andFigure figure 1 show that anemic hemodialysis patients were 247 patients (98.8%) and non-anemic patients were 03 patients (1.2%).

The distribution of anemic hemodialysis patients according to the degrees of anemia was 42 patients (17%) with severe anemia, 177 patients (71.66%) with moderate anemia, and 28 patients (11.34%) with mild anemia (Table 2&#x00026;Figure 2).

The distribution of anemic hemodialysis patients according to the types of anemia was 33 patients (13.36%) with Microcytic hypochromic, 204 patients (82.59%) with normocytic hypochromic, and 10 patients (4.05%) with macrocytic hypochromic anemia (Table 3 &#x00026;Figure 3).

The data shown inTable table 4 andFigure figure 4 showed a significant (P<0.01) decrease in RBCs counts (3.24 &#x000b1; 0.04) x10⁶ cell/&#x003bc;l in the hemodialysis patients compared with the healthy individuals (4.81 &#x000b1; 0.04) x10⁶ cell/&#x003bc;l.

A significant (P<0.01) decreased in hemoglobin concentrations (9.27 &#x000b1; 0.10) g/dl were recorded in the hemodialysis patients when compared with the healthy individuals (14.21 &#x000b1; 0.11) g/dl (Table 4 &#x00026;Figure 5).

Hematocrit values were a significantly (P<0.01) decreased (27.97 &#x000b1; 0.35%) in the hemodialysis patients when compared to the healthy individuals (41.33 &#x000b1; 0.30%) (Table 4 &#x00026;Figure 6).

A significant ((P<0.01) increase was observed in mean corpuscular volume (MCV) (87.36 &#x000b1; 0.41fl) of hemodialysis patients compared with the healthy individuals (85.11 &#x000b1; 0.60fl) (Table 4 &#x00026;Figure 7).

A significant (P<0.05) decrease in MCH (28.84 &#x000b1; 0.16) was observed in the hemodialysis patients when compared with the healthy individuals (29.40 &#x000b1; 0.14) (Table 4 &#x00026;Figure 8).

Table 4 &#x00026;Figure figure 9 were showed a significant (P<0.01) decrease in MCHC (32.90 &#x000b1; 0.11) in the hemodialysis patients when compared with the healthy individuals (34.32 &#x000b1; 0.10).

WBCs count was showed a significant (P<0.01) decrease (6.39 &#x000b1; 0.13) x10³ cell/&#x003bc;l in the hemodialysis patients as compared to the healthy individuals (7.80 &#x000b1; 0.18) x10³ cell/&#x003bc;l (Table 5 &#x00026;Figure 10).

The data recorded inTable table 5 andFigure figure 11 indicated a none significant (P>0.05) changes was observed in neutrophils % (63.79&#x000b1; 0.77) in the hemodialysis patients as compared with the healthy individuals (63.63 &#x000b1; 1.48).

Lymphocytes % was significantly (P<0.01) decreased (24.05 &#x000b1; 0.69) in the hemodialysis patients when compared with the healthy individuals (29.43 &#x000b1; 0.81) (Table 5 &#x00026;Figure 12).

The blood platelets count was significantly (P<0.01) decreased (203.06 &#x000b1; 4.03)x 10³/&#x000b5;l in the hemodialysis patients when compared with the healthy individuals (241.50 &#x000b1; 5.55) x 10³/&#x000b5;l (Table 5 &#x00026;Figure 13).

Data inTable table 6 show the correlation between RBCs count, Hb, Hct, and MCV with hematological parameters. A significant (P<0.01) positive correlation was observed between RBCs count with Hb, Hct, and WBCs (r = 0.851, 0.838, and 0.236, respectively), and lymphocytes% (P= 0.042, r = 0.129). While, a significant (P<0.01) negative correlation was recorded between RBCs count with MCV, MCH, and MCHC (r = -0.296, -0.401, and -0.265, respectively).

A significant (P<0.01) positive correlation was observed between Hb concentration with RBCs count, Hct, and WBCs (r = 0.851, 0.831, and 0.177, respectively), and MCV, and lymphocytes% (P= 0.020&#x00026; 0.037, r = 0.148, 0.32, respectively).

A significant (P<0.01) positive correlation was observed between Hct value with RBCs count, Hb, WBCs, and lymphocytes% (r = 838, 0.831, 0.174, and 0.224, respectively). While, a significant (P<0.01) negative correlation was recorded between Hct value with MCHC (r = - 0.279).

Also, a significant (P<0.01&#x00026; P<0.05) positive correlation was observed between mean corpuscular volume with MCH and Hb (r = 0.834 &#x00026; 0.148), respectively. While, a significant (P<0.01) negative correlation was recorded between mean corpuscular volume with RBCs count (r = - 0.296).

Data inTable table 7 show the correlation between serum urea, creatinine, and uric acid with hematological parameters. A significant (P<0.01) negative correlation was observed between serum urea with Hb (r = 0.174), and RBCs count and Hct (P= 0.010&#x00026; 0.027, r = 0.172&#x00026; 0.146, respectively). While, a significant (P<0.01) positive correlation was recorded between uric acid with platelets count (r = 0.232).

Data inTable table 8 show the correlation between gender and blood groups with hematological data. A significant (P<0.05) positive correlation was observed between gender with platelets count (r = 0.163), while, a significant negative correlation was recorded between gender with serum urea (P<0.01, r =-0.220), creatinine (r = -0.391), and uric acid (P<0.05, r=-0.180), and Hb (P<0.05, r=-0.160).

A significant (P<0.01) negative correlation was observed between blood groups with serum uric acid (r=-0.225).

Data inTable table 9 show the correlation between body weight and durations of hemodialysis with hematological data. A significant positive correlation was observed between body weight with WBCs count (P<0.01, r = 0.236), and serum uric acid (P<0.05, r = 0.162).

A significant (P<0.01) positive correlation was observed between durations of hemodialysis with RBCs count (r = 0.206) and Hb (r = 0.184), while, a significant (P<0.05) negative correlation was recorded between durations of hemodialysis with body weight (r =-0.157), and MCHC (r=-0.131).

The present study aimed to evaluate the prevalence of anemia and investigate the variations of hematological parameters among hemodialysis patients in Tripoli region

In chronic kidney disease patients, RBCs count, hemoglobin concentration, hematocrit value, MCHC, and MCH are changed compared with the healthy individuals [ 26]. The kidneys are the main site of erythropoietin synthesis which is the primary regulator of erythropoiesis [ 27], that produce approximately 90% of erythropoietin by the Juxta glomerular apparatus (JGA), while the liver and other organs are produce about 10% of it [ 26].

The results of the current study showed a significant decreased in RBCs counts, Hb, Hct, MCH, and MCHC, and increase in MCV in the hemodialysis patients compared with the healthy individuals. These results run parallel with those obtained by the previous studies [ 27,28,29,30,31]. Olasunkanmi et al. [ 26] and Singh and Bhatta [ 30] reported that hemoglobin concentration, Hct value, and RBCs count were significantly changes in chronic kidney disease patients compared with the healthy individuals.

The present study showed that the prevalence of anemia among hemodialysis patients was 89.8%. The degrees of anemia were 17% severe, 71.66% moderate, and 11.34% mild anemia. The types of anemia were 13.36% microcytic hypochromic, 82.59% normocytic hypochromic, and 4.05% macrocytic hypochromic anemia. These results are in concordance with those of the previous studies [ 26,32].

The moderate and normocytic normochromic anemia were the most prevalent [ 26]. Juma, [ 32] mention that the prevalence of anemia was 97% (26% mild, 31% severe, and 40% moderate and 47.4% normocytic normochromic, 28.9% microcytic hypochromic, 16.5% normocytic normochromic and microcytic hypochromic, 5.2% macrocytic, and 2% microcytic normochromic) in patients with chronic kidney disease at Muhimbili national hospital Dar Essalaam. The severity of anemia is directly proportional to the degree of renal function [ 33]. Rathod et al., [ 34] mentioned that the most common anemia in chronic renal failure is normochromic normocytic, which can be correlated with the severity of renal failure. A severe anemia was observed in 18% of renal failure patients [ 35], mild, and moderate anemias were recorded in up to 69% and 100% of patients [ 36] and Normochromic normocytic blood picture is commonly seen in chronic disorders specially in renal failure patients, which is seen in all patients in Nigeria [ 26,36], but a low percent (30%) was recorded in India, macrocytic anemia is seen in 5% of patients, and microcytic hypochromic is seen in 65% of patients [ 37].

Erythropoietin hormone regulates RBCs production and preserve the viability of RBCs by retarding the cleavage of deoxyribonucleic acid. When the EPO is absent, the cleavage of deoxyribonucleic acid is rapid which leads to the death of cells [ 30,38]. Also, EPO excites the effect of , and megakaryocyte colony activating factors [ 30,39].

The main causes of the decrease in red blood cell count, hemoglobin concentration, and hematocrit in chronic kidney disease patients are decrease in the production of erythropoietin, factors increase hemolysis, low levels of serum iron, suppression of bone marrow erythropoiesis, hematuria and gastrointestinal blood loss, and decrease of RBCs life span [ 26,30,40,41,42,43,44,45,46]. Also, the affinity of hemoglobin to oxygen decreases and the availability of O₂/unit of Hb circulating through the kidney increases [ 34]. In addition, iron and folate deficiency, and chronic disease with endogenous erythropoietin resistance, heavy metal toxicity, blood loss, and a reduction in red cell survival induced by toxic radicals are from the contributing factors [ 47]. Iron replacement is required in the treatment of renal failure anemia [ 40].

Proinflammatory cytokines antagonize the action of erythropoietin by inhibiting erythroid progenitor cells and disrupting iron metabolism in renal failure patients. Erythropoietin resistance may be induced by inflammation. Also, it could be caused by inflammation-induced changes in erythropoietin-receptor properties, recycling, and assembly and by interference with post-receptor signaling routes. In addition, Neocytolysis might have a role in erythropoietin resistance [ 48], which is a physiological process initiated by a drop in erythropoietin levels, leads to selective hemolysis of young circulating red blood cells and subsequent down regulation of red cell mass when it is excessive [ 49].

Arogundade et al. [ 36], and Akinsola et al. [ 50] reported that the degree of anemia was worsened with the progression of chronic kidney disease.

The present study showed a significant decrease in WBCs count and lymphocytes % in the hemodialysis patients compared with the healthy individuals. These results are in agreement with the result of the previous studies [ 30,33]. Olasunkanmi et al, [ 26] and Singh and Bhatta, [ 30] recorded that WBCs count was significantly changes in chronic kidney disease patients compared with the healthy individuals. Wasti et al.[ 33] mentioned that the lymphocytes count was decreased in 16.3% of chronic kidney disease patients which may be due to severe stress, kidney failure, chronic infections, and prolonged use of cortisone injection.

The decline of WBCs count in chronic kidney disease patients during dialysis is because of complement activation which causes the aggregation of neutrophils and adherence to the internal wall of the blood vessels [ 30,51]. Suresh et al. [ 28] reported that WBCs count showed a non-significant decreased in CKD patients.

On the other hand, Kadhim et al. [ 31] observed an increase in WBCs count in CKD patients compared to the control group, which caused by up regulation, presence of interleukin-6 (IL-6) and TNF-&#x003b1; in blood, that contribute to inflammation in renal failure patients [ 31,52].

The current study appeared a significant decrease in platelets count in the hemodialysis patients compared with the healthy individuals. This result is compatible with the result of Abdu et al. [ 37] who reported that the prevalence of thrombocytopaenia in chronic kidney disease patients was 52%. Mohamed, [ 53] confirmed that the patients with renal failure are at high risk of bleeding due to decrease of platelets count and platelet dysfunction. Also, Dorgalaleh et al. [ 5] found that platelet count was a significant decreased in chronic renal failure patients. In addition, Olasunkanmi et al., [ 26] and Singh and Bhatta, [ 30] mentioned that platelet count was significantly changes in chronic kidney disease patients compared with the healthy individuals. In patients with CKD the decrease of EPO leads to fall in platelets count [ 30,39].

On the other hand, Kadhim et al. [ 31] recorded a significant increase in platelet count among CKD patients compared to the control group.

Previous studies were showed that a negative correlation was observed between serum creatinine concentration and hematological parameters in renal failure patients and the degree of changes depends on the severity of the disease (Suresh et al., 2012, and George et al., 2015).

It can be concluded that a higher prevalence of moderate, normocytic hypochromic anemia among hemodialysis patients. In addition, results showed a significant variation in hematological parameters among the anemic hemodialysis patients. So, hemodialysis patients advice to examine the hematological parameters and treated from anemia if detected.