| Abstract|| |
To determine the nutritional status of chronic hemodialysis (HD) patients and the association of changes in serum albumin levels, C-reactive protein (CRP), Low Density Lipoprotein (LDL) cholesterol and body mass index (BMI) as indicators of nutritional status with the urea reduction ratio (URR) during dialysis, we studied 201 chronic HD patients (97 males and the mean age was 51 ± 15 years). Diabetes was the cause of chronic kidney disease (CKD) in 34% of the patients, hypertension in 57%, chronic glomerulonephritis in 12%, and obstructive uropathy in 10%. BMI less than 18.5 (under weight) was found in 17% of patients, more 18.5 but less than 25 (normal) in 56%, more than 25 but less than 30 (overweight) in 21%, and more than 30 (obese) in 6%. The laboratory investigations revealed hypercalcemia in 62% of the patients (15 patients were found to have tertiary hyperparathyroidism), total cholesterol less than 100 mg/dL in 6% (mean 152 ± 37.5 mg/dL), and URR of less than 60% in 12% of patients and greater than 60 but less than 65% in 33%. Hypoalbuminemia was associated with poor URR (P< 0.05), whereas no statistically significant correlation was found between URR and iPTH, LDL cholesterol, CRP and body mass index. We conclude that poor nutritional status was detected among a significant number of our patients with poor dietary education. Increased risk of malnutrition was significantly associated with older age and inadequate dialysis dose. Hypoalbuminemia was the single most important factor associated with poor URR.
|How to cite this article:|
Abbas HN, Rabbani MA, Safdar N, Murtaza G, Maria Q, Ahamd A. Biochemical nutritional parameters and their impact on hemodialysis efficiency. Saudi J Kidney Dis Transpl 2009;20:1105-9
|How to cite this URL:|
Abbas HN, Rabbani MA, Safdar N, Murtaza G, Maria Q, Ahamd A. Biochemical nutritional parameters and their impact on hemodialysis efficiency. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2019 Dec 6];20:1105-9. Available from: http://www.sjkdt.org/text.asp?2009/20/6/1105/57278
| Introduction|| |
Renal replacement therapy by dialysis is essential for the survival of patients with end-stage renal disease (ESRD).  Malnutrition is an evident problem in 40-50% of patients with ESRD, and it is associated with increased infection; poor wound healing, muscle wasting and increased mortality.
Malnutrition is caused by inadequate dietary intake, anorexia, gastrointestinal disturbances, psychosocial and socioeconomic factors or unmet increased nutritional requirements due to impaired protein or energy and/or concomitant diseases namely cardiovascular disease, sepsis and inflammation.  When dialysis therapy is started, the uremic symptoms are reduced, the diet is less restricted, and some patients may show improved nutritional status.  However, the results of cross-sectional studies throughout the world indicate that maintenance HD patients are still at risk of malnutrition.  This could be due to the losses of nutrients into dialysate, chronic blood loss, inflammation and associated diseases.  We conducted this study to assess the nutritional status of our ESRD patients on maintenance HD and the association of changes in serum albumin levels, C-reactive protein (CRP), Low Density Lipoprotein (LDL) cholesterol, and body mass index (BMI) as indicators of nutritional status with urea reduction ratio (URR) during dialysis
| Patients and Methods|| |
We studied the records of 201chronic HD patients at our dialysis center from October 1, 1990 till September 2004. We excluded from the study the patients who were on maintenance hemodialysis for less than six months, not receiving their prescribed dialysis dose, showed persistent non-compliance with their dialysis therapy, or were diagnosed with liver cirrhosis and proteinuria. The analysis of the data included primary causes of kidney disease, co-morbid conditions, age, sex, duration on dialysis, frequency of hemodialysis, dialyzer size, dialyzer membrane, reprocessing details, Hepatitis B and C status, average blood flow, height, weight, etc. Relevant laboratory investigations included serum albumin, cholesterol, CRP concentrations, and urea reduction ratio (URR) (defined as the percent reduction in blood urea nitrogen concentration during a single dialysis treatment).
| Statistical Analysis|| |
The data feeding and analysis were done on computer package "EPI-info" version 6.0 software of CDC (Centre for Disease Control, Atlanta, USA).
The results were expressed as the mean ± standard deviation (SD). Chi-square and student's "t" test were used for comparison of quantitative variables, whereas Pearson Co-efficient correlation was used to determine the association between the markers of nutritional status and URR. A P-value of < 0.05 is considered statistically significant.
| Results|| |
The 201 study patients included 97 male and 69 (34%) diabetics. The mean age was 51 ± 15 years. [Table 1] shows the characteristics of the study patients. The cause of kidney disease was hypertension in 57% of the patients followed by diabetes in 34%. Of the patients, 83% received hemodialysis therapy thrice a week, 35% received dialysis for more than 5 years, 95 % used 1.5 m 2 dialyzers, 74% re-used dialyzers, 97% received regular erythropoietin therapy, 8% was hepatitis BsAg positive, and 16% was Hepatitis C antibody positive.
Sixty two percent of the patients was unemployed and a 65% of them was supported by welfare department of hospital for coverage of hemodialysis costs. Weekly meat consumption was reported by more than 95% of patients, and weekly egg consumption in more than 90%. In 74% of the patients dialysis was initiated as an emergency and in 26% as a planned intervention; the main reasons were acidosis (35%), pulmonary edema (32%), uremic symptoms (25%) and hyperkalaemia (3%). In 91% of patients temporary access was used at the time of dialysis initiation. More than 80% of patients had some form of sexual dysfunction.
[Table 2] shows the means of the biochemical parameters of the study patients. Hb less than 10 gm/dL was found in 10% of the patients, 1012 gm/dL in 54%, and greater than 12 gm/dL in 36%. Hypoalbuminemia (serum albumin less than 3.8 gm/dL) was revealed in 73% of patients and hypercalcemia in 62%. Tertiary hyperparathyroidism was found in 15 patients and secondary hyperparathyroidism in 31. Total cholesterol less than 100 mg/dL was found in 6% of the patients, more than 100 but less than 150 mg/dL in 46%, and more than 150 mg in 48%. BMI was less than 18.5 in 17% of the patients (under weight), more than 18.5 but less than 25 (normal) in 56%, more than 25 but less than 30 (overweight) in 21%, and more than 30 (obese) in 6%. CRP was found elevated in 18% of the patients. URR less than 60% was found in 12% of the patients, greater than 60 but less than 65% in14%, and greater than 65 but less than 71% in 32%, and greater than 70% in 41%. Hypoalbuminemia and elevated CRP were associated with poor URR (P< 0.05), whereas no statistically significant relationship was found between URR and iPTH and LDL cholesterol [Table 3].
| Discussion|| |
The incidence of ESRD patients in Pakistan, who are maintenance hemodialysis dependant (MHD) for their survival, is estimated to be 100 patients/million population. 
These patients experience a low quality of life, increased hospitalizations, and a high mortality rate; currently 20% annually in the USA. The causes of deaths in MHD patients are diverse, however, at least half of them die of cardiovascular disease.  Up to 40-67% of patients have Protein energy malnutrition (PEM), a complication that appears to be associated with increased mortality.  In addition to high prevalence of PEM in MHD patients, its strong association with underlying inflammatory/infective process (as indicated by C-reactive protein [CRP] has become an established fact. ESRD associated chronic inflammation as assessed by CRP level has been reported in 30-60% of North American and European dialysis patients. 
Hypocholesterolemia, a strong mortality risk factor in dialysis patients and a marker of poor nutritional status was present in 52% of our patients. One of the possible factors that result in hypocholesterolemia is believed to be due to inflammation.  In addition, 73% of our patients revealed hypoalbuminemia, which is the single laboratory finding most closely associated with an increased mortality. 
BMI was less than 18.5 in 17% of patients (under weight), and more than 30 in 6% (obese). It correlates directly with body fat and can be used as a marker of energy nutritional status. 
Numerous studies have documented the relationship between poor outcome in MHD patients with inadequate urea reduction ratio(URR), , probably secondary to reappearance of a more subtle form of the uremic syndrome with progressive catabolism and PEM, while increased KT/V results in a significant reduction of mortality. , Increasing the URR from 61 to 70 percent reduced mortality rate from 22.5 down to 18.1 percent per year;  the improvement was achieved with standard cellulosic bioincompatible membranes. In our study, 45% of patients had URR less than 65.
In contrast to general population, where markers of over nutrition are associated with increased risk of cardiovascular disease, decrease nutritional measures in dialysis patients are strongly correlated with increased morbidity/mortality, including a higher risk of cardiovascular events and death. These paradoxical observations have been referred to as "reverse epidemiology" or "risk factor-paradox".  This may not necessarily indicate that the principles of vascular pathophysiology are different in the ESRD patients but may denote other superimposed and more dominant factors that cause apparent reversed relationship between risk factors and outcome.  It has been suggested, but remains unproven, that this paradoxical association is spurious and results from either reversed causation in which cardiovascular disease leads to inflammation and/or malnutrition and lower cholesterol levels, or a confounding effect of inflammation and/or malnutrition, which leads to lower cholesterol levels and higher mortality. 
In our dialysis population only 6.5% of our patients had high serum cholesterol (> 200 mg/ dL), whereas 17% of patients had high LDL levels (> 100 mg/dL), which has been consistently associated with lower mortality in prospective studies in dialysis patients with marked contrast to the prospective studies and clinical trial findings in the general population. ,
Currently, it is not clear how cardiac disease, inflammation, hypoalbuminemia and other measures of PEM in dialysis patients are interrelated.  It has been postulated that inflammation is the common link.  A common mechanism for the development of CVD and PEM in dialysis patients may be the cytokine activation that is associated with reduced renal function or other pro-inflammatory conditions in dialysis patients such as the frequent contact with dialyzer membranes, vascular access grafts, catheters, or dialysate; each may constitute a pro-inflammatory factor.  Increased release or activation of inflammatory cytokines, such as interleukin-6 or tumor necrosis factor-alpha, may suppress appetite, cause muscle proteolysis and hypoalbuminemia, and lead to atherosclerosis.  Nevertheless, the degree to which PEM in dialysis patients is caused by inflammation is not clear. Some studies suggest that PEM and inflammation each independently contribute to hypoalbuminemia and subsequently increase morbidity/mortality. 
We conclude that poor nutritional status was detected among a significant number of our patients with poor dietary education. Increased risk of malnutrition was significantly associated with older age and inadequate dialysis dose. Hypoalbuminemia was the single most important factor associated with poor URR.
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Malik Anas Rabbani
Kidney Center, Post Graduate Training Institute, 197/9, Rafiqui Shaheed Road Karachi-75530
[Table 1], [Table 2], [Table 3]