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INTRODUCTION
Chronic kidney disease (CKD) is increasing rapidly in the world as well as in Vietnam due to the rapid increase of kidney damage causes such as diabetes and hypertension. Based on the changing of glomerular filtration rate, chronic kidney diseases are divided into five sequential and successive stages. From stage 3 to stage 5 of chronic kidney disease (glomerular filtration rate < 60 ml/min) is considered as chronic renal failure. When glomerular filtration rate < 15 ml / min, patients need kidney replacement therapy such as hemodialysis or kidney transplantation.
Anemia is common in patients with chronic kidney disease. Anemia is often caused by a combination of three causes: dysfunction of hematopoietic organs, lack of hematopoietic materials and bleeding, in which lack of erythropoietin and iron deficiency are two important factors. Iron deficiency oftens occurs in patients with renal failure (glomerular filtration rate < 60 ml/min). Patients with end stage chronic kidney disease often have high proportion of iron deficiency, but in hemodialysis patients, iron overload often occurs. Both situations affects to the quality of anemia treatment in this group of patients.
As the recommendation of the National Kidney Foundation Disease Outcomes Quality Initiative (NKFK/DOQI), to treat anemia effectively in patients with chronic kidney disease, besides providing erythropoietin, patients should be supplemented with amino acids, trace elements and iron in particular. In patients with chronic kidney disease, it is necessary to determine the status of serum iron storage and its classification: iron deficiency, enough iron and iron overload. This recommendation also mention that sufficient iron compensation should be based on ferritin and transferin saturation. Transferrin saturation is calculated through serum iron and Total Iron Binding Capacity (TIBC). Thus, there are three most necessary quantities to assess iron deficiency status: iron, ferritin and TIBC.
In Vietnam, there have been many studies on the status of serum iron, ferritin and transferrin in patients with chronic renal failure, but there have not been many studies that mention to TIBC and the status of iron storage which is recommended by the K/DOQI in patients with chronic kidney disease who have not undergoing renal replacement therapy. For the above reasons, we conducted the study "Study on the concentration of
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plasma iron, ferritin, and total iron binding capacity in chronic kidney disease patients without renal replacement" 1. Objectives of the study The study was conducted in patients who were diagnosed with chronic kidney disease (glomerular filtration rate < 60 ml/min) and had not been treated with kidney replacement therapy in the Department of Nephrology and Hemodialysis, Military Hospital 103, with the following two objectives: Describe the characteristics of anemia, the concentration of plasma iron, ferritin, TIBC and assess the status of iron storage according to the KDIGO in stage 3 to 5 chronic kidney disease patients without renal replacement. Determine the relationship between concentrations of plasma iron, ferritin, TIBC, the iron storage status with some characteristics of chronic kidney disease patients without renal replacement. 2. The urgency of the study Anemia is a common manifestation in CKD patients, especially in patients with GFR < 60 ml/min (renal failure). The mechanism of anemia in CKD patients involves Erythropoietin deficiency and lack of hematopoietic materials including iron. Iron supplementation for anemia treatment in CKD patients requires a scientific basis and is a difficult problem for clinicians. As the recommendation of the World and Vietnam Kidney Association, it is necessary to determine the status of iron storage before iron compensation. Assessment of iron status should be based on serum ferritin concentration and transferin saturation, in which transferin saturation is calculated by serum iron and TIBC concentrations. Thus, the study on the concentration of iron, ferritin and TIBC, thereby determining the status of iron storage in CKD patients who have not been treated by kidney replacement therapy, is a necessary study for clinical practice. 3. New contributions of the thesis
This is the first study in Vietnam that quantifies serum TIBC concentration, that recommended by the Kidney Associations to use along with serum iron and ferritin concentrations to assess the iron storage status of CKD patients who have not been treated by kidney
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replacement therapy. The results of the study confirmed that mean value of serum TIBC concentration in CKD patients was lower than that of normal control group. The results also showed high proportion of patients with lack of iron storage. There are some factors related to TIBC and iron storage reduction. Based on this results, clinicians will have a strategy to compensate for iron, improve the effectiveness of anemia treatment for patients with chronic kidney disease. 4. Thesis structure: The thesis includes 116 pages. Introduction: 2 pages, literature review: 34 pages, subjects and methods: 16 pages, results: 30 pages, discussions: 31 pages, conclusions and recommendations: 3 pages. In the thesis, there are 43 tables, 14 charts, 1 diagram, 2 pictures. The thesis has 136 references, including 21 Vietnamese and 115 English references. Chapter 1: LITERATURE REVIEW
1.1. Anemia in patients with chronic kidney disease According to the World Health Organization, anemia is a condition that reduces circulating hemoglobin in peripheral blood below normal levels of people with the same sex, age and in the same living environment. According to International Society of Nephrology, in patients with chronic kidney disease, anemia was diagnosed when Hb < 130g/l for men, Hb < 120g/l for women and Hb < 110g/l for pregnant women. 1.2. Assessing the status of iron storages in patients with chronic kidney disease Clinically, there are many indicators assessing iron function of healthy people, CKD and kidney failure patients. KDOQI and KDIGO recommend some commonly used indicators such as serum iron, ferritin, transferin, TIBC concentration and transferrin saturation (TSAT). To assess the status of iron storage, International Society of Nephrology recommends that we mostly based on ferritin and TSAT. Calculation of TSAT according to the following formula: Plasma iron (µmol/l) x 100 TSAT (%) = Plasma TIBC (µmol/l) + Absolute iron deficiency:
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CKD patients who have not been treated by kidney replacement therapy: Plasma ferritin concentration < 100ng/ml and/or serum transferrin saturation level < 20%. Patients with hemodialysis: Plasma ferritin concentration < 200 ng/ml and/or serum transferrin saturation level < 20%. + Functional iron deficiency: plasma ferritin concentration ≥ 200ng/ml and/or serum transferrin saturation level < 20%.
+ Iron overload in CKD patients who have not been treated by kidney replacement therapy: serum ferritin concentration ≥ 500ng/ml and/or TSAT ≥ 50% 1.3. Studies on concentrations of serum iron, ferritin and TIBC in CKD patients.
+ In the world, there had been many studies on the use of serum TIBC, iron and ferritin concentrations to assess iron storage status in patients with and without dialysis. Numerous studies had evaluated the results of iron compensation in anemia treatment in patients with chronic kidney disease.
+ In Vietnam: there were some studies on serum iron and ferritin levels, however, there had been no studies on TIBC and iron storage status in chronic renal failure patients who have not been treated by kidney replacement therapy. Chapter 2: SUBJECTS AND METHODS
2.1. Subjects The study was conducted on 190 subjects who was divided into 2 groups:
Study group: 124 patients with stage 3 to 5 chronic kidney disease, who have not been treated by kidney replacement therapy (GFR < 60 ml/min), at the Department of Nephrology and Hemodialysis, Military Hospital 103.
Normal control group: 66 healthy people. Research period: 01/2014 – 04/2018. + Inclusion criteria Control group: healthy adults who do not have kidney or urinary diseases, agree to participate in the study.
Study group: Patients with stage 3 to 5 chronic kidney disease who have not been treated by kidney replacement therapy, age of 16 years
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old and above, agree to participate in the study.
+ Exclusion criteria Control group: Acute blood loss within the previous 3 months or bleeding. People who are pregnant or have just given birth within the last 6 months.
Study group: Blood transfusion during the previous 3 months. Acute blood loss within the previous 3 months or bleeding during the study period. Patients have been taking iron or iron preparations. Patients have an indication for emergency dialysis. 2.2. Methods
A descriptive, crosssectional, comparative casecontrol study Sample size calculation: Percentage of patients with chronic renal disease with iron deficiency from 54.4% to 63.5% in previous studies. Calculation of the sample size according to the following formula: (Z1α/2)2 x p (1p) n = D2 In which: Z = 1,96, with a reliability of 95%
p = 0,544 (lowest value in previous studies) D = 0,1, the desired accuracy.
According to the calculation, the study must have at least 96 patients. In the study, n = 124 patients were used.
2.2.1. Study targets Patients admitted to hospital, were asked for medical conditions and were taken medical examination according to the research form. The following criteria were collected: Age, gender, history of disease Measuring for blood pressure, height, weight and BMI calculation. Laboratory tests include: hematology, biochemistry (glucose, urea, creatinine, albumin, uric acid, four blood lipid indices, electrolytes, hs CRP...) Quantitative determination of plasma iron, ferritin, and TIBC levels: venous blood was taken when patients were hungry in the early morning. Plasma iron and ferritin concentration were quantified on Cobas 6000 system, which using the kit of Roche company, in
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Department of Biochemistry, Military Hospital 103. Serum TIBC concentration were quantified by ELISA method at Department of Pathophysiology, Vietnam Military Medical University for both study and control groups. Calculating glomerular filtration rate under the guidance of NKF K/DOQI using the MDRD formula which was based on creatinine, age, gender and race. Calculation of transferrin saturation by plasma iron and TIBC concentrations. The iron storage status was divided base on the recommendation of KDIGO and KDOQI throughout the ferritin and TSAT indices. The diagnostic, classification and evaluation standards were based on recommendations of national and international specialized associations. Evaluation of increasing or decreasing plasma iron, ferritin and TIBC levels were based on control group results. 2.2.2. Data processing The data was processed according to the medical statistical method using SPSS software program version16.0. The algorithms were used include: multivariate logistic regression analysis, calculating mean values, standard deviations, percentages, comparing two average values and percentage by ttest, compare ratios by Chisquare test, comparing mean values by Anova test, calculating the correlation coefficient (r). 2.2.3. Ethics in research The study did not violate ethics in medicine, serving for screening for chronic kidney disease patients. The study was approved by the Department of Heart Kidney Joints Endocrinology, Vietnam Military Medical University before implementation. TIBC test fee was payed by myself. Chapter 3: RESULTS
3.1. General characteristics of subjects Age and gender characteristics: + Control group included 66 people with average age of 41.86 ± 5.68 years, men accounted for 69.7% and women accounted for 30.3%.
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+ The research group included 124 patients whose average age was 52.65 ± 17.95 years, men accounted for 72.6% and women accounted 27.4%. The cause of CKD: Chronic glomerulonephritis accounted for 49.2%, chronic renal pyelonephritis accounted for 16.9%, hypertension accounted for 15.3%, diabetes accounted for 12.9 %, the lowest due to polycystic kidneys and Gout which accounted for only 3.2% and 2.4% respectively. The proportion of stage 5 CKD patients accounted for 79.8%, stage 3 and 4 accounted for 20.2%. The average glomerular filtration rate was 8.3 ml/min. Up to 89.5% of patients had hypertension in the study, only 10.5% of patients did not have hypertension. The group of patients with normal BMI accounted for the highest rate (70.2%), the proportion of overweight and obesity accounted for only 15.3% and underweight accounted for 14.5%. The average value of BMI was 20.05 3.2. Characteristics of anemia, concentrations of plasma iron, ferritin, TIBC and iron storage status following to KDIGO in patients with chronic kidney disease 3.2.1. Characteristic of anemia in study group Table 3.1. The percentage of patients on the severity of anemia (n = 124) Severity of anemia
No anemia Anemia
Number 05 119 34 43 42 Percentage 4.0 96.0 27.4 34.7 33.9 Mild Moderate Severe Average Hemoglobin (g/l) 91.13 ± 22.01
The proportion of anemia was 96.0%, the average Hb concentration was 91.13 g/l. Mild, moderate and severe anemia accounted for 27.4%, 34.7% and 33.9% respectively.
Table 3.2. Percentage of patients according to the size of red blood cells (n=119) Erythrocyte size Percentage Number
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Microcytic Normocytic Macrocytic 12 107 0 10.1 89.9 0
In group of anemia patients, there were 10.1% of patients with microcytic anemia and 89.9% of patients with normocytic anemia.
Table 3.3. Percentage of patients according to the amount of hemoglobin in each cell (n=119)
Anemia classification Hypochromic anemia Normochromic anemia Hyperchromic anemia Number 42 74 3 Percentage 35.3 62.2 2.5
Among patients with anemia, hypochromic anemia accounted for 35.3%, this proportion of hyperchromic anemia was 2.5%. The highest proportion was normochromic anemia with 62.2%. 3.2.2. The concentrations of plasma iron, ferritin and TIBC in the study subjects
Table 3.4. Comparison of concentrations of plasma iron, ferritin and TIBC between study group and control group
Indices p
< 0.001 Iron* (µmol/l)
Median (IQR) Min Max
Ferritin* (ng/ml) < 0.001 Median (IQR)
< 0.001 TIBC* (µmol/l) Min Max Mean Min Max Control group (n=66) 15.81 (11.56 – 19.26) 7.3 31.4 198.45 (68.05 – 255.22) 16.5 383.4 67.58 ± 11.58 46.12 90.63 Study group (n=124) 10.7 (6.62 – 15.25) 2.1 41.6 403.73 (211.36 548.42) 31 1070.1 50.64 ± 19.79 17.5 98.21
* Approximate normal range by control group: Iron (Percentiles 2.5% 97.5%): 7.31 29.8 µmol/l; Ferritin (Percentiles 2.5% 97.5%): 16.77 375.16 ng/ml; TIBC: Mean ± 1.96xSD: 44.89 90.27 µmol/l
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Plasma iron and TIBC concentrations in study group were significant lower than in control group, p < 0.001. In contrast, plasma ferritin concentration in study group was sighnificant higher than in control group, p < 0.001. Table 3.5. The proportion of patients with increasing or decreasing concentrations of plasma iron, ferritin and TIBC compared to control group (n=124) Indices
Iron (µmol/l)
Ferritin (ng/mL)
TIBC (µmol/L) Decrease Normal Increase Decrease Normal Increase Decrease Normal Increase Number 36 84 4 0 56 68 59 63 2 Percentage 29 67.7 3.2 0 45.2 54.8 47.6 50.8 1.6
The proportion of patients with normal concentration of plasma iron was 67.7%. Up to 29% of patients had decreasing and 3.2% of patients increasing plasma iron concentration compared to control group. Meanwhile, 54.8% of patients increased plasma ferritin concentration compared to control group. The proportion of patients with decreasing TIBC concentration was 47.6%. There was only 1.6% of patients who had increasing TIBC concentration. 3.2.3. Assessment of serum iron storage status according to KDIGO guideline in the study group
Table 3.6. Characteristics of transferin saturation in study group (n=124)
Male (n=90) Female (n=34) P Characteristics
> 0.05 Both gender (n=124) % n 30.6 38 61.3 76 8.1 10 n 26 55 9 % 28.9 61.1 10 n 12 21 1 % 35.3 61.8 2.9 Low Normal High Median (IQR) 22.31 22.3 22.02 > 0.05
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(17.77 – 33.5) (18.5 – 34.47) (13.29 – 26.68)
The proportion of patients with low TSAT (< 20%) was 30.6%. There was 8.1% of patients with high TSAT (> 50%), while normal TSAT accounted for a major proportion (61.3%). There was no difference of TSAT characteristics between men and women. The median value of TSAT was 22.31%.
Table 3.7. Characteristics of iron storage status in study group according to KDIGO guideline (n=124)
Iron storage status * Iron deficiency Enough iron Iron overload Percentage 37.1 24.2 38.7 Number 46 30 48 * Iron deficiency: Ferritin < 100 and/or TSAT < 20%; Iron
overload: Ferritin > 500 and/or TSAT > 50% Based on the recommendation of KDIGO for patients with non dialysis chronic kidney disease, the proportion of patients with iron deficiency in the study was 37.1%, however, there were also 38.7% of patients with iron overload. 3.3. The relationship between concentrations of plasma iron, ferritin, TIBC, iron storage status and some characteristics of patients with chronic kidney disease 3.3.1. The relation to the stage of chronic kidney disease ả B ng 3.8. Comparison of mean values of plasma iron, ferritin and TIBC concentrations between stages of chronic kidney disease (n=124)
Stages of CKD Iron (µmol/L) Median TIBC (µmol/L) X ± SD
3+4 (n = 25) 68.44 ± 16.36
5 (n = 99) 46.15 ± 18.02
p 10.16 (7 – 14.58) 10.7 (6.6 – 15.6) > 0.05 Ferritin (ng/mL) Median 252.6 (177.89 – 437) 435.5 (250.49 – 557.68) < 0.001 < 0.05
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Plasma iron concentration was not related to the stages of chronic kidney disease with p > 0.05. However, plasma ferritin concentration in patients with stage 5 chronic kidney disease was significant higher than that of patients in stage 3 and 4 (p < 0.05). In contrast, the concentration of TIBC in patients with stage 5 chronic kidney disease was lower than that of patients in stage 3 and 4 (p < 0.001). Table 3.9. The proportion of patients with increasing or decreasing concentration of plasma iron, ferritin and TIBC between stages of chronic kidney disease (n=124)
Indices p Stage 3 + 4 (n = 25) Stage 5 (n = 99)
7 (28) 29 (29.3) > 0.05 Iron (mmol/l)
< 0.05 Ferritin (ng/mL)
< 0.001 TIBC (µmol/L) 18 (72) 0 (0) 0 (0) 17 (68) 8 (32) 3 (12) 22 (88) 0 (0) 66 (66.7) 4 (4) 0 (0) 39 (39.4) 60 (60.6) 56 (56.6) 42 (41.4) 2 (2) Decrease (n, %) Normal Increase Decrease Normal Increase Decrease Normal Increase
There was no difference in the proportion of patients with with increasing or decreasing concentration of plasma iron concentration between stages of chronic kidney disease. In contrast, the proportion of increasing plasma ferritin concentration in stage 5 chronic kidney disease patients was significant higher than that of patients in stage 3 and 4, p < 0.05. The proportion of decreasing TIBC concentration in patients with stage 5 chronic renal disease was significant higher than that of patients in stage 3 and 4, p < 0.001. Table 3.10. The relationship between iron storage status and stages of chronic kidney disease in study group (n=124) Stages of Iron deficiency Enough iron Iron overload
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(n, %) 15 (60) 31 (31.3) (n, %) 5 (20) 43 (43.4) CKD 3 +4 (n=25) 5 (n=99) p (n, %) 5 (20) 25 (25.3) < 0.05
The proportion of iron deficiency in stage 3 and 4 CKD patients was sighnificant higher than that of stage 5 CKD patients. In contrast, the proportion of iron overload in stage 5 CKD patients was significant higher than that of stage 3 and 4 (p <0.05). 3.3.2. The relation to anemia
Table 3.11. The correlation between plasma iron, ferritin, TIBC and hemoglobin concentration (n=124) Hemoglobin (g/l) Indices Correlation equation
Iron (µmol/L) Ferritin (ng/ml) r 0.037 0.134 p > 0.05 > 0.05
TIBC (µmol/L) 0.208 < 0.05 TIBC= 0.168*Hemoglobin + 32.474
Plasma iron and TIBC concentration had a weak positive correlation while plasma ferritin concentration had a weak negative correlation with hemoglobin concentration (p <0.05). 3.3.3. The relation to plasma CRP and albumin
Table 3.12. The relationship between concentrations of plasma iron, ferritin, TIBC and albumin concentration in study group (n=120)
Albumin concentration Iron (µmol/L) (Median) TIBC (µmol/L) ( X ± SD)
47.05 ± 20.63 Decrease (<35g/l) (n=57) 8.1 (4.85 – 11.9)
Normal (n=63) 54.12 ± 18.88 11.9 (9.1 – 17.7)
p < 0.001 Ferritin (ng/mL) (Median) 428.23 (187.5 – 563.09) 380.39 (236.76 – 488.28) > 0.05 > 0.05
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Iron (µmol/L) (Median) CRP concentration Plasma iron concentration in patients with decreasing albumin concentration was significantly lower than that of patients with normal albumin concentration (p <0.01). There was no difference between plasma ferritin and TIBC concentrations and albumin concentration status with p > 0.05. Table 3.13 The relationship between concentrations of plasma iron, ferritin, TIBC and CRP concentration in study group (n=112) TIBC (µmol/L) ( X ± SD)
46.52 ± 19.73 Increase > 5 mg/l (n=48) 6.87 (4.35 – 12.34)
54.89 ± 19.45 No increase (n=64) 11.9 (8.8 – 18.6)
p < 0.001 Ferritin (ng/mL) (Median) 431.25 (231.5 – 567.73) 385.2 (193.1 – 544.61) > 0.05 < 0.05
In the group of patients with increasing hsCRP concentration, plasma iron and TIBC concentrations were significant lower than that of non increasing group (p < 0.05). In contrast, plasma ferritin concentration in patients with increasing hsCRP were not significant difference with nonincreasing hsCRP group (p > 0.05). 3.3.4. The plasma TIBC in evaluating iron storage in study group
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Sensitivity Sp = 73.9%
Specificity Se = 69.2%
Area under the curve AUC = 0.755; p < 0.001 Cutoff value= 48.03
Chart 3.1. The ROC curve for iron storage deficiency diagnosis of plasma TIBC concentration Comment: At the cutoff value of 48.03µmol/L, plasma TIBC concentration had a diagnostic value for iron deficiency. The higher TIBC concentration, the more valuable of diagnostic value (p <0.001 and area under the curve AUC= 0.755). 3.3.5. Multivariate regression analysis of the associated risk factors that affected to the decreasing plasma TIBC concentration and iron deficiency
Table 3.14. Multivariate regression analysis of the associated risk factors that affected to the decreasing plasma TIBC concentration (n=124) Factors p
Age ≥ 60 Female Albumin< 35 g/l Odds ratio (OR) 1.387 0.595 1.411 Confidence interval 95% 0.538 – 3.576 0.217 – 1.630 0.522 – 3.814 > 0.05 > 0.05 > 0.05
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1.718 0.439 0.831 19.363 0.65 – 4.539 0.116 – 1.654 0.318 – 2.173 3.884 – 96.53 > 0.05 > 0.05 > 0.05 < 0.001
1,287 0,284 – 5,826 > 0,05 CRP > 5 BMI < 18.5 First diagnosis GFR<15 ml/min Ferritin < 100 ng/ml
Multivariate logistic regression model: Log ( ) = 2.625 + 0.327*
Age of 60 and above 0.519* Female + 0.344* Decreasing Albumin + 0.541* Increasing CRP 0.823* BMI lower than 18.5 0.185* First diagnosis + 2.963* GFR below 15ml/min + 0.253* Ferritin lower than 100ng/ml. GFR <15 ml/min was an independent risk factor for the decrease of plasma TIBC concentration in patients with stage 3 to 5 CKD without kidney replacement therapy (p <0.001).
Table 3.15. Multivariate regression analysis of the associated risk factors that affected to the iron deficiency (n=124) Factors p
Odds ratio (OR) 0.961 2.036 0.489 2.579 0.578 12.177 0.353 Confidence interval 95% 0.342 – 2.702 0.676 – 6.129 0.155 – 1.54 0.805 – 8.267 0.126 – 2.655 3.407 – 43.516 0.093 – 1.336 > 0.05 > 0.05 > 0.05 > 0.05 > 0.05 < 0.001 > 0.05
9.612 2.974 – 31.073 < 0.001 Age≥ 60 Female Albumin< 35 g/l CRP > 5 BMI < 18.5 First diagnosis GFR<15 ml/min TIBC > 48.03 µmol/L
Multivariate logistic regression model: Log ( ) = 2.568 0.04* Age
of 60 and above + 0.711* Female 0.715* Decreasing Albumin + 0.948* Increasing CRP 0.547* BMI lower than 18.5 + 2.5* First diagnosis 1.041* GFR lower than 15ml/min + 2.263* TIBC higher than 48.03. First diagnosis and increasing plasma TIBC concentrations were independent risk factors of iron deficiency (p <0.001).
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Chapter 4: DISCUSSION
4.1. General characteristics of study group In our study group, male accounted for a majority proportion. Glomerulonephritis accounted for nearly a half of CKD causes. Our results were consistent with other author’s results. The patients with stage 5 CKD were predominant. Patients mostly had unpleasant clinical manifestations such as anemia, nausea, headache… (manifestations of prolonged uremic syndrome) The proportion of patients with hypertension was high, which was consistent with the characteristics of chronic kidney disease. 4.2. Characteristics of anemia, concentrations of plasma iron, ferritin, TIBC and iron storage status in study group 4.2.1. Characteristic of anemia in study group Anemia is a common manifestation in patients with CKD, even if patient has no renal failure. The prevalence of anemia in our study was 88.6% with an average hemoglobin level of 97.14 g/l. When compared with domestic and foreign authors, we found that the proportion and severity of anemia differed in the studies. Table 4.1. Comparison of anemia among studies
Authors Subjects Proportion of anemia Mean value of Hemoglobin
53.1% 126 g/l Mercadal L. et al. (2014)
51.5 % 126.33 g/l
44.9 % 126.5 g/l
75.8 % 109 g/l Li Y. et al. (2016) Ryu S.R. et al. (2017) Salman M. et al. (2016)
96.0% 91.13 g/l Our study (2018) 1011 stage 15 CKD patients. Mean GFR of 35.9 ml/min 2420 stage 15 CKD patients 2198 stage 15 CKD patients 615 CKD patients with GFR of 27.8 ml/min 124 stage 35 CKD patients. Mean GFR of 8.3 ml/min
For patients with stage 15 CKD, the incidence of anemia as well as the mean value of hemoglobin concentration showed similar results: The lower GFR, the higher anemia proportion as well as the lower the
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hemoglobin concentration. Our study group had the lowest GFR, so the highest anemia proportion and the lowest hemoglobin concentration in our study were understandable. When analysis of the nature and characteristics of anemia, we found that in 119 anemia patients, the proportion of patients with microcytic anemia accounted for 10.1% and hypochromic anemia accounted for 35.3%. Anemia in patients with CKD was usually characterized by normochromic and normocytic anemia, but when the GFR was significant reduced, especially in patients with endstage kidney failure, anemia tent to be hypochromic anemia and red blood cell size became smaller. Thus our research results were consistent with literature. 4.2.2. The concentrations of plasma iron, ferritin and TIBC in study group In this study, because there was no TIBC concentration reference range for Vietnamese people, we used control groups to determine the cutoff point and the percentage of patients with increasing or decreasing TIBC concentration. Distribution of iron and ferritin concentration was not according to the normal distribution, so we determined TIBC reference range base on the range of 2.5% percentile and 97.5% percentile (iron: 7.31 – 29.8 µmol/l; ferritin: 16.77 375.16 ng/ml; TIBC: 44.89 90.27 µmol/l). The results showed that serum iron and TIBC concentrations in study group were significant lower than in control group, while serum ferritin concentration was significant higher than in control group (p <0.001). Our results were consistent with results of domestic and foreign authors.
Authors, subjects Ferritin (ng/ml) TIBC (µmol/l)
88.66 Control: 36 healthy people 77.8 (418.1 μg/dl)
Gupta S. et al. (2009) 513.82 55.28 (297.2 μg/dl)
Table 4.2. Comparison of concentrations of plasma iron, ferritin and TIBC between studies Iron (µmol/l) 12.4 (66.65 µg/dl) 18.8 (101.5 µg/dl) 14.06 56.5 110 102 stage 5 CKD patients – hemodialysis 199 stage 1 5 CKD patients Mercadal L. et al.
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157.7 100 stage 3 5 CKD patients 11.16 (60 µg/dl) 62.78 (337.5 μg/dl) (2015) Goyal H. et al. (2017) 15.81 198.45 67.58
Our study (2018) 10.7 403.73 50.64 Control: 66 healthy people 124 stage 3 5 CKD patients
Thus, with the same quantitative method and calculation unit, our results as well as other authors showed that iron and TIBC concentrations in CKD patients without dialysis were lower than in control group, while serum ferritin concentration was higher in control group. Based on the results of control group, we calculated the proportion of increasing and decreasing of these indices. Our results showed that 29% of patients had decreasing and 3.2% of patients had increasing plasma iron concentration. There was no patients with decreasing plasma ferritin concentration, but 54.8% of patients had increasing plasma ferritin concentration compared to the control group. There was 7.6% of patients with decreasing TIBC concentration and only 1.6% of patients with increasing TIBC concentration compared to the control group. 4.2.3. Characteristics of transferrin saturation and iron storage status in the study group * Characteristics of transferrin saturation in the study group
Evaluating characteristics of transferrin saturation, we found that 30.6% of patients had TSAT <20% and also 8.1% of patients had TSAT> 50%. Only 61.3% of patients had TSAT within the normal limits. The average value of TSAT was 22.31%. When compared with the results of domestic and foreign authors, we found similarities. In the study of Phan The Cuong in 2015 on 105 endstage CKD patients, mean value of TSAT was 21.8%. 52.4% of patients had low TSAT (<20%) and 1.9% of patients had high TSAT (>50%). The study of Waziri B et al. in 2016, the mean value of TSAT in 67 patients with stage 35 CKD was 24.45%. The study of Li Y. et al. in 2016 on 1338 patients with stage 3 CKD had a mean value of TSAT of 23.62%. Thus, the results of foreign authors with the same research subjects were the same as ours.
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The results of Phan The Cuong had a higher proportion of TSAT < 20% and lower mean value because in that study,100% of patients was end stage CKD, while our study had only 79.8 % of patients with stage 5 CKD. * Characteristics of iron storage status in the study group Based on the recommendation of KDIGO for patients with non dialysis chronic kidney disease, the proportion of patients with iron deficiency in our study was 37.1%. However, up to 38.7% of patients had iron overload. If only based on the ferritin status, the rate of iron deficiency was only 8.9%. So up to 28.2% of patients had wrong assessment of iron deficiency and there was a missed diagnosis of 4.0% of patients with iron overload. If iron overload patients continue to receive iron compensation, patients will be overloaded and iron poisoning. Conversely, if 28.2% of patients are not compensated, it will lead to poor treatment for anemia. The calculation of iron status for CKD patients is extremely important because besides providing EPO, proper and adequate iron supplementation is required in clinical practice.
Table 4.3. Comparison of serum iron status according to KDIGO among studies
Authors Subjects
The proportion of patients with Ferritin < 100 ng/ml and/or TSAT < 20%
61.3% Trivedi H.S. et al. (2003)
54.4 % Ryu S.R. et al. (2017)
63.5 % Fishbane S. et al. (2012)
Our study (2018) 37.1% 31 CKD patients with mean value of GFR of 22.9 ml/min 2198 stage 15 CKD patients 26142 CKD patients with 6.6% of patients with stage 35 CKD 124 stage 35 CKD patients with mean value of GFR of 8.3 ml/min
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In CKD patients with and without renal failure, we found that the proportion of patients with absolute iron deficiency according to KDIGO standards in various studies was different. Our results had a lower proportion of iron deficiency compared with other authors' results, although our subjects had the lowest mean value of GFR. Explaining this, we believed that this may cause by the difference of race. 4.3. The relationship between concentrations of plasma iron, ferritin, TIBC, iron storage status and some characteristics of patients with chronic kidney disease 4.3.1. The relation to the stage of chronic kidney disease Plasma iron, ferritin and TIBC concentrations were related to the stage of CKD: The group of patients with stage 3 + 4 CKD had a higher mean value of plasma iron, lower mean value of ferritin and lower mean value of TIBC concentration than patients with stage 5 CKD, however, only the difference of ferritin and TIBC concentration was statistically significant with p < 0.05. The proportion of decreasing serum iron concentration was not different by the stage of chronic kidney disease. We only found differences in the proportion of increasing ferritine and decreasing TIBC concentration by the stage of chronic kidney disease (p < 0.001). Plasma ferritin concentration was not correlated with creatinine concentration. TIBC had a negative correlation with creatinine concentration with correlation coefficient r = 0.39 and p < 0.01. The proportion of patients with iron deficiency increased along with the severity of chronic kidney disease. The results of Lukaszyk E. et al. in 2017 on 84 CKD patients in which 28 patients with GFR of 3059 ml/min and 56 patients with GFR of 60 ml/min and above. The results were similar to ours. GFR was not correlated with plasma concentration, however GFR had a negative correlation with plasma ferritin concentration. The study of Alam F et al. in 2015 on 126 CKD patients who were divided into 3 subgroups: 42 patients with mean value of GFR of 79 ml/min, 42 patients with mean value of GFR of 45 ml/min and 42 patients with mean value of GFR of 20.22 ml/min. The concentration of serum iron decreased gradually from the group of patients with higher GFR to lower GFR group, while the mean value of ferritin concentration increased gradually (p <0.001).
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The study of Waziri B. et al. in 2016 on 67 stage 35 CKD patients and Mercadal L. et al. in 2015 on 199 stage 15 CKD patients showed that serum TIBC concentration decreased gradually along with the reduction of glomerular filtration rate. 4.3.2. The relation to anemia In order to answer the question of whether iron storage was related to the anemia characteristics of stage 35 CKD patients or not, we conducted an assessment on the group of anemia and without anemia. When conducting the correlation of plasma iron, ferritine and TIBC concentrations with some peripheral hematological indices such as Hemoglobin and Hematocrit, we found that TIBC had a weak positive correlation with two indices above (p < 0.05). We found that plasma iron and ferritin concentration were not correlated with two indices above. 4.3.3. The relation to the plasma CRP and albumin When comparing mean concentrations of plasma iron, ferritin and TIBC in decreasing albumin and normal albumin groups, we found that decreasing albumin group had lower iron concentration and higher TIBC, ferritin concentrations than normal albumin group, however only plasma iron had a significant difference with p <0.01. For further analysis, we determined the correlation between plasma iron, ferritin, TIBC and albumin concentration. The results showed that only plasma iron had a weak positive correlation with albumin concentration (p <0.05). The study of Sezer M.T. et al. in 2007 also showed that low albumin concentration was a risk factor for the production of oxidants caused by iron overload. Malnutrition and inflammation had a closely relation. In inflammatory patients often had albumin reduction and vice versa. In this study, we determined the relationship between plasma iron and hsCRP concentrations. The results showed that patients with increasing plasma hsCRP concentration had a higher mean value of iron and ferritin concentration and lower mean value of plasma TIBC concentration than group of patients with normal hsCRP concentration. However, only plasma iron and TIBC had a significant difference between two group above with p < 0.001. There was a moderate negative correlation between plasma iron and hsCRP concentrations (r = 0.229, p < 0.05). Małyszko J. et al. in 2012 evaluated ironrelated
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factors of 98 endstage CKD patients with hemodialysis. The results showed that the mean value of albumin concentration in patients with decreasing plasma iron concentration was 37.5 g/l which was significant lower than that of the group of patients without decreasing plasma iron concentration (40.6 g/l) with p < 0.05. In contrast, the mean value of hsCRP concentration in patients with decreasing plasma iron concentration was 7.11 mg/l which was significant higher than that of the group of patients without decreasing plasma iron concentration (5.32 mg/l) with p <0.01. 4.3.4. The plasma TIBC in evaluating iron storage The question is what factors can assess the iron storage status when we can not calculate TSAT? As we know, free iron had a limited significance, so K/DIGO recommends that we should rely on ferritin and TSAT to assess iron status. We found that TIBC had a diagnostic value of iron deficiency at a cutoff value of 48.03 µmol/L. In fact, although it is recommended to use the concentration of ferritin and TSAT to assess iron storage status, nephrologists often rely on plasma ferritin to assess the CKD patient's iron storage status, thereby providing specific iron supplement regimens for each patient. Thus, TIBC can be used as a tool to evaluate iron storage status for CKD patients. 4.3.5. Multivariate regression analysis of the associated risk factors that affected to the decreasing plasma TIBC concentration and iron deficiency Although univariate analysis had many factors that related to decreasing of plasma iron and TIBC concentration as well as increasing ferritin concentration. However, when using multivariate analysis, we found that there were some key points to consider for clinicians. Using multivariate regression analysis of the associated risk factors that affected to the decreasing plasma TIBC concentration, we found that GFR < 15 ml/min was an independent risk factor of decreasing plasma TIBC concentration (p < 0.05). Typically, iron is absorbed from food and transported throughout the body by transferrin which is produced by the liver. About 70% of iron is transported to the bone marrow and combined with hemoglobin in red blood cells. The rest is stored in tissues such as ferritin or hemosiderin. The amount of transferrin in the blood depends on the liver function and the nutritional status of the
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individual. TIBC is an index that measures the amount of iron that can bind to blood proteins, including transferrin and other proteins (in which transferrin is the main protein binding iron). Because TIBC nature is also a protein, it changes in the elderly group. In patients with chronic kidney disease, malnutrition increases along with decreasing GFR and increasing inflammation. In multivariate regression analysis of risk factors that affected to the iron deficiency, we found that first diagnosed CKD and TIBC > 48.03 µmol/L were independent risk factors for iron deficiency (p < 0.01). Anemia in CKD patients is usually normochromic anemia, but the iron deficiency status was increased gradually along with the reduction of GFR, despite of increasing ferritin concentration. Thus, first diagnosed CKD patients had a very high possibility of iron deficiency. This results had a clinical significance in the diagnosis of iron storage deficiency and iron supplementation should be given to patients when the patient is diagnosed with lowGFR CKD from the first time regardless of serum iron quantification.
LIMITATION OF THE STUDY Although the study had achieved the given objectives, however, the proportion of stage 3 and 4 CKD patients was quite small, so the change of plasma iron, ferritin, TIBC concentration and iron storage status in this group of patients has not been clear. CONCLUSION
Characteristics of anemia, concentrations of plasma iron,
Study on plasma iron, ferritin and TIBC concentrations in 124 non dialysis CKD patients and compare with 66 healthy people, we draw some conclusions: 1. ferritin, TIBC and iron storage status in study group. * Characteristics of anemia + The proportion of anemia in study group accounted for 96%, including 33.9% of severe anemia, 34.7% of moderate anemia and 27.4% of mild anemia. The mean value of hemoglobin concentration was 91.13 g/l. + Characteristics of anemia: 10.1% of microcytic anemia and 35.3% of hypochromic anemia.
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* Concentrations of plasma iron, ferritin and TIBC in patients with
stage 3 to 5 chronic kidney disease + In study group, the mean value of plasma iron and TIBC concentration was lower, while the mean value of ferritin concentration was higher than that of control group (p <0.001). There were 29% of patients with decreasing plasma iron concentration, 54.8% of patients with increasing ferritin concentration and 47.6% of patients with decreasing plasma TIBC concentration compared with the reference range of control group. + When based on ferritin concentration and transferrin saturation to diagnos iron status (KDIGO recommendation): 37.1% of patients had iron deficiency, 24.2% of of patients had enoug iron and 38.7% of patients had iron overload. 2. The relationship between concentrations of plasma iron, ferritin, TIBC, iron storage status and some characteristics of patients with chronic kidney disease Decreasing plasma iron, TIBC concentration, increasing ferritin concentrations and iron storage deficiency related to patient characteristics: + In patients with stage 5 CKD, the mean value of TIBC concentration was lower, while the mean value of ferritin concentration was higher than that of stage 3 and 4 patients (p <0.05). However, there were a positive correlation between iron and creatinine and a negative correlation between TIBC and creatinine with the correlation coefficients of 0.201 and 0.390 respectively (p <0.05). + TIBC concentration had a positive correlation with hemoglobin and hematocrit (the correlation coefficient r = 0.208 and 0.191 respectively, p < 0.05). + The reduction of iron storage significantly associated with decreasing albumin and increasing CRP concentration (p < 0.05). At the cutoff value of 48.03 µmol/L, TIBC had a diagnostic value for iron deficiency status (p < 0.001, AUC= 0.755, Se = 73.9% and Sp = 69.2%). + GFR < 15 ml/min is an independent prognostic factor for decreasing TIBC concentration.
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RECOMMENDATIONS
Through research, we draw out the following recommendations: 1. Conducting another studies with a larger sample size and in all stages of chronic kidney disease to draw conclusions about plasma iron, ferritin and TIBC concentration in CKD patients. 2. Reducing the concentration of albumin and increasing the concentration of CRP have been associated with decreased levels of TIBC. It is necessary to control inflammation and improvement nutrition for patients to ensure normal levels of TIBC.
LIST OF PAPERS ON THE DISCLOSURE OF RESEARCH RESULTS OF THE THESIS TOPIC
ễ ễ ậ ệ ắ t Th ng
1. Nguy n Văn Hùng, Nguy n Cao Lu n, Lê Vi
(2018). Survey on the relationship between serum concentration
of iron, ferritin and some characteristics in patient with stage 3
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ạ ượ ọ c h c to 5 chronic predialysis kidney disease. T p chí Y d
quân sự, 43(9): 114120.
ễ ễ ậ ệ ắ t Th ng
2. Nguy n Văn Hùng, Nguy n Cao Lu n, Lê Vi
ế ắ ủ ắ ắ ả ẩ ị (2018). Giá tr ch n đoán thi u s t c a kh năng g n s t toàn
ế ươ ầ ở ệ ậ ạ T pạ ph n trong huy t t ng b nh nhân suy th n m n tính.
ọ ệ chí Y h c Vi t Nam , 470 (2): 47.
