CHAPTER ONE
1.0 INTRODUCTION
Chronic renal failure (CRF) is defined as either kidney damage or GFR<60mL/min/1.73m 2 for≥3months. Kidney damage is defined as pathologic abnormalities or markers of damage, including abnormalities in blood or urine test or imaging studies.
In United Kingdom the prevalence of CRF is approximately 600 individuals per million population per year (0.06%).
2 The incidence of end stage renal failure (ESRF) is of the order of 200 per million population per year (0.02%) 2. In Nigeria, although accurate figures are not available, the size of the problem has been estimated using hospital admission records. Hospital admission rates of CRF in South -West Nigeria vary from 1.6%to 6.7%-8%. 3,4 However, much earlier reports by Adetuyibi et al showed that CRF accounted for 11.4% of deaths on the medical wards of a major teaching hospital in the region 5. Hence CRF is not uncommon amongst Nigerians. Chronic glomerulonephritis, hypertension and diabetes mellitus account for the majority of CRF cases in Nigeria with obstructive uropathy and autosomal dorminant polycystic kidney diseases accounting for smaller proportions 4.Uptill two decades ago, diabetes mellitus was reported to be an uncommon cause of CRF in Nigeria, but in the last few years, reports from several Renal Units in the country now place diabetes nephropathy as the third most common cause of CRF 3,6.
There are several irreversible but modifiable complications of chronic renal failure and these include anemia, cardiovascular disease, metabolic bone disease and malnutrition. These complications begin early in the course of renal failure 7. Patients on maintenance haemodialysis are at risk of developing malnutrition. Malnutrition in these patients is associated with reduced life expectancy because of infections and cardiovascular complications 8. Adequate nutrition is essential to life. Many of the major medical problems of public health importance in all parts of the world have either a nutritional basis or at least an important nutritional contribution. This includes chronic renal failure. This is particularly important because of the huge economic cost of maintaining such patients on renal replacement therapy 9. It has been shown that renal diet is not palatable to most patients and this therefore modifies their eating habit 10. Previous study has identified protein malnutrition as the main factor responsible for mortality and morbidity in dialysis patients. 11, Low serum albumin has also been reported to be an adverse prognostic factor in adults with end stage renal disease on continuous peritoneal dialysis 11,12. Malnutrition has been shown to lead to progressive decline in glomerular filtration rate, decreased excretion of acid or osmolar load, decreased urinary phosphate excretion, diminished response to expanded extra cellular volume and higher incidence of urinary tract infection.
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13 Addition of soybeans protein to low protein diet has been
demonstrated to have effectively reduced the rate of chronic renal failure progression.
1.1 ASSESSMENT OF NUTRITIONAL STATUS
No single method is appropriate in evaluating nutritional status in CRF patients before the initiation of dialysis therapy and when on haemodialysis. Most authors agree that a multiparametric evaluation in which various assessments are included is most appropriate. 8,14 Nutritional status is conventionally assessed by mea ns of a combination of anthropometric measurements and laboratory assessments 14,15. The National Kidney Foundation recommends the following tools for use in adult dialysis patients and these include; (a) normalized protein equivalent of nitrogen appearance (n PNA), which is derived from the daily net generation of urea and is normalized to the body weight. (b) serum albumin and pre-albumin which measure proteins in the blood. (c) subjective global assessment, which is a set of observation based on patients symptoms and physical examination findings (d) anthropometry is a measure of skin fold thickness and other aspects of body composition. (e) dual energy x-ray absorptiomentry (DEXA) which is an x ray technique measuring the components of body mass 69. Some studies have also recommended the use of total daily protein intake as a nutritional marker 16,17,18. However, measurement of food intake is difficult because individual food intake fluctuates and the
fluctuation can be due to social and economic reasons. Change in appetite also accounts for substantial change in food intake from day to day and week to week. Measuring food intake also does not absolutely indicate whether or not an individual is malnourished, since this will depend on the effectiveness of absorption, on the individual’s specific needs and on any metabolic change in utilization. Accurate assessment of the nutritional status of an individual therefore requires direct measurement of body size, nutrient stores, metabolism and functional capacity. 19,20 Anthropometry involves measurements of subcutaneous fat as skin fold thickness and skeletal muscles as mid arm circumference, these are important to determine the severity of malnutrition. Other anthropometric factors associated with malnutrition include low body weight and hand grip strength. The use of anthropometry is limited by the requirement of specialized calipers, the experience of the observer, and the potential confounding effects of oedema or dehydration.
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Biochemical factors that are associated with malnutrition include visceral proteins like serum albumin, pre_ albumin, transferring, serum levels of creatinine, plasma levels of insulin – like growth factor 1 (IGF- 1) and branched chain amino acid (isoleucin e, leucine and valine). Factors that can influence albumin values include age, sex and serum c-reactive protein. Other studies have reported the use of serum levels of tumor necrosis factor - 1, cholesterol, Immunoglbulins, urea, phosphorus, potassium bica rbonate, transferrin, total lymphocyte
count, alpha -1-acid glycoprotein and ceruloplasmin as markers of either nutritional intake or body protein or muscle mass. 18,20 Malnutrition is present in 42% - 77% of end-stage renal disease population in developing countries , is strongly associated with increased morbidity and mortality 21 and is common in patients on maintenance haemodialysis. However, in another study, a 40% prevalence of malnutrition was found in patients with advanced renal failure at the beginning of dialysis treatment 8,16. In other studies it has been demonstrated that about one third of patients have mild to moderate malnutrition and 6 to 8% have severe malnutrition 8. Signs of malnutrition are observed in 10-70% of haemodialysis patients and 18- 51% of patients on continuous ambulatory peritoneal dialysis.
There is paucity of data regarding the prevalence of protein malnutrition in the CRF population in developing countries. However, Agaba et al using body mass index (BMI) and serum protein levels studied the prevalence of malnutrition among 74 Nigerians with CRF before commencement of dialysis therapy. Protein malnutrition (serum albumin < 29g/l) was present in 32 (43.2 %) of patients with CRF and only one (2%) of the control subjects 23 suggesting protein malnutrition is common in Nigerian CRF patients.
1.2 OBJECTIVES OF THE STUDY
1.2.1 a) General:- To assess the nutritional status of CRF patients before the initiation of dialysis therapy.
1.2.2 b) Specific: (1) - To determine the baseline prevalence of malnutrition in CRF patients before dialysis therapy. (2) To correlate the nutritional status with the glomerular filtration rate (GFR) of CRF patients.
1.3 Relevance of the study
1. Malnutrition often begins before patients with chronic kidney disease develop end stage renal failure. The physical fitness of these patients as evident by their nutritional status at the time of initiation of dialysis therapy plays a pivotal role in their long term survival. Screening for malnutrition early in the course of CKD can help detect patients at risk of malnutrition so that health care providers can offer nutrition intervention, thus improving out comes and lowering cost. 2. Most of the previous work done on nutrition in CRF patients were either carried out in patients on maintenance dialysis therapy or ESRF with little known about the prevalence of malnutrition before dialysis treatment and its relationship with the level of renal insufficiency. Hitherto, there has been only one local study on the prevalence o f malnutrition before dialysis but it was not correlated with the level of renal function, neither was the multiparametric method used to assess nutritional status. 3. To add to our knowledge of what is already known about malnutrition in CRF and the prevalence.
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