|Year : 2018 | Volume
| Issue : 4 | Page : 91-94
Assessment of nutritional status in a patient with chronic kidney disease: How Do I Do It?
Department of Nephrology, Consultant Nephrologist, Renal Transplant Physician, Global Hospital, Sir HN Reliance Foundation Hospital and Research Center, Mumbai, Maharashtra, India
|Date of Web Publication||19-Sep-2019|
Dr. Shruti Tapiawala
Global Hospital, Mumbai, Maharashtra, Sir HN Reliance Foundation Hospital and Research Center, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Studies report a high prevalence of protein-energy malnutrition in patients with chronic kidney disease (CKD) and in dialysis-dependent end-stage kidney disease (ESKD) patients. The strongest evidence comes from the Modification of Diet in Renal Disease study, which showed that, in patients with CKD, as renal function decreases, dietary protein and energy intake, anthropometric parameters, and biochemical markers of nutrition progressively decline. Even we have observed that the calorie and protein intake of Indian patients with CKD and ESRD is poor. This article discusses the methods to assess dietary intake in CKD and ESKD on maintenance dialysis.
Keywords: Chronic kidney disease, dialysis, protein-energy malnutrition
|How to cite this article:|
Tapiawala S. Assessment of nutritional status in a patient with chronic kidney disease: How Do I Do It?. J Renal Nutr Metab 2018;4:91-4
|How to cite this URL:|
Tapiawala S. Assessment of nutritional status in a patient with chronic kidney disease: How Do I Do It?. J Renal Nutr Metab [serial online] 2018 [cited 2019 Dec 12];4:91-4. Available from: http://www.jrnm.in/text.asp?2018/4/4/91/267204
| Introduction|| |
Western and Indian studies report a high prevalence of protein-energy malnutrition (PEM) in patients with chronic kidney disease (CKD) and in patients with end-stage kidney disease (ESKD) on dialysis. The strongest evidence comes from the Modification of Diet in Renal Disease study, which is the largest multicenter trial performed in the USA.,,,, This study showed that, in patients with CKD, as renal function decreases, dietary protein and energy intake, anthropometric parameters, and biochemical markers of nutrition progressively decline. Even we have observed that the calorie and protein intake of Indian patients with CKD and ESRD is poor. Besides the fact that nutrient intake declines with progressive renal failure, other factors also contribute to malnutrition in patients with chronic renal insufficiency (CRI). These include decreased nutrient utilization, intercurrent illness, altered hormonal and metabolic function, and imposed restrictions on diet. Malnutrition has an important clinical implication because it is well known that malnutrition is a powerful predictor of morbidity and mortality. This makes it necessary to assess the nutritional status of renal failure patients periodically and take measures to prevent PEM. The various methods commonly used for the assessment of nutritional status are dietary recall, anthropometric measurements, and biochemical parameters, such as albumin, pre-albumin, and transferrin. These methods have to be used in conjunction and are time-consuming and complex. Subjective global assessment (SGA) is simple, reliable, and dynamic. It provides a sound estimation of nutritional status.,,,,
Malnutrition is a common finding in patients with CKD and ESKD. In recent years, the importance of nutritional assessment in patients with CKD and ESKD has been emphasized by studies showing that malnutrition is associated with an increased risk of morbidity and mortality. Nutritional assessment should detect malnutrition and rate the overall nutritional status of each patient through clinical data categories: medical history, physical examination, nutrition physical examination, psychosocial history, demographics, physical activity, and current medical/surgical issues. A periodic assessment of nutritional status and taking appropriate measures are important in improving the outcome.
| Methods to Assess Dietary Intake in Chronic Kidney Disease and End-stage Kidney Disease on Maintenance Dialysis|| |
Examining the quality and quantity of food intake by appropriate methods is critical in the management of patients with CKD. The four commonly used dietary assessment methods in CKD patients include short-term dietary recalls, several days of food records with or without dietary interviews, urea kinetic-based estimates such as protein nitrogen appearance calculation, and food histories, including food screeners and food frequency questionnaires. There are a number of strengths and limitations of these dietary assessment methods. A number of studies in individuals without renal diseases indicate that diet diaries and interviews provide quantitative information concerning intake of protein, energy, and other nutrients. The same applies to the patients with CKD and patients on maintenance hemodialysis (MHD) and continuous ambulatory peritoneal dialysis (CAPD). However, the validity and reliability of the dietary interviews and diaries depend on the patient's ability to provide accurate data and ability of a nutritionist to conduct detailed, probing interviews. Accordingly, none of the four methods is suitable in and of itself to give sufficiently accurate dietary information for all purposes.
| Urea Dynamic-based Estimates of Dietary Protein Intake|| |
By virtue of end-stage renal failure, most maintenance HD patients cannot excrete a significant amount of urinary nitrogen. Hence, the rate of increase in serum urea nitrogen between two consecutive HD sessions reflects dietary nitrogen intake, provided that the individual is not in substantially negative or positive nitrogen balance. This indirect but conveniently available measure of protein intake is referred to as the urea kinetic-based protein equivalent of total nitrogen appearance (PNA) or protein catabolic rate (PCR), which is usually normalized (n) for the patient's body weight or an estimate of the volume of distribution of urea, hence the term nPNA or nPCR.
The commonly used calculation is as follows.
Urea nitrogen appearance method by Maroni et al.
For stable patients:
Nitrogen intake = Nitrogen loss
Total nitrogen loss = 24-h urinary urea nitrogen (urea × 28/60) + extrarenal loss (0.031 × weight in kg)
If 24-h urinary urea N2 is 6 g and weight is 60 kg,
Extrarenal nitrogen loss = 1.86 g and the total N2 loss = 6 + 1.86 = 7.86 g
Then, protein intake = 7.86 × 6.25 = 49.12 g
Hence, the protein intake of this person is
49.12 g/60 kg = 0.8 g/kg/day.
Some protocols also collect urinary urea excretion and add this to the calculations for nPNA. nPNA, as a measure of dietary protein intake, may have a bearing on clinical outcome in HD patients, and so, several studies have examined the association between nPNA and survival in dialysis patients
| Assessment of Nutritional Status by Biochemical Parameters|| |
Biochemical parameters such as serum albumin, transferrin, and pre-albumin levels are extensively used to assess the nutritional status. They do not necessarily correlate with changes in other nutritional parameters and can be influenced by nonnutritional factors. The nonnutritional factors that can affect these parameters are infection, inflammation, hydration status, peritoneal or urinary albumin losses, and acidemia. The drop in serum albumin, which is the most widely used parameter of assessing nutritional status, is not only less specific but also lags behind the onset of malnutrition. Low albumin is seen only when PEM manifests overtly.,,,,,,,,,,
| Assessment of Nutritional Status by Anthropometry|| |
Anthropometry provides a semi-quantitative estimate of the components of body mass, particularly the bone, muscle, and fat compartments, and thus gives us information concerning nutritional status. Height, weight, and trends in weight over time are the simplest and most useful anthropometric measurements. Lean body mass (consists of fat-free body mass or body weight minus the weight of the body fat) is one of the parameters to assess body fat. Mid-arm muscle circumference is simple to do but only grossly abnormal with far-advanced protein-calorie malnutrition. Other anthropometric measurements such as skin folds at the triceps have to be used with proper training. Bioelectrical impedance is less reliable when edema is present.,,,,,,,,,,
However, it requires precise techniques of measurement and the use of proper equipment to give accurate and reproducible data.
| Inflammation and Its Implications|| |
Many CKD and HD patients show evidence of chronic inflammation, with intermittent or persistently elevated levels of acute-phase proteins, C-reactive proteins (CRPs) being the one most widely used in clinical practice. An elevated CRP is often accompanied by decrease in serum albumin, which acts as an inverse acute-phase protein. Blood–membrane interactions are known to result in complement activation and release of cytokines from macrophages. There is substantial evidence that dialysis with complement-activating membranes has an acute catabolic effect. This may be through both a decrease in protein synthesis and an increase in breakdown mediated through cytokines such as tumor necrosis factor-α (TNF-α) and interleukin 1 (IL-1). Membrane compatibility was assessed in few studies. It has been hence suggested that biocompatible membranes be used to decrease the protein catabolism.
Peritoneal dialysate, which is bio-incompatible, is more likely to stimulate cytokine production from peritoneal mesothelial cells, as well as through the activation of monocytes and neutrophils, which contributes to increased catabolism in CAPD. Pro-inflammatory cytokines (IL-1, IL-6, TNF) appear to play a pivotal role by causing muscle wasting, hypoalbuminemia, and anorexia, as well as cardiac contractility and atherosclerotic vascular disease. Apart from the traditional risk factors, low Vitamin E levels, as mentioned earlier, elevated CRP levels are associated with increased carotid intima-media area and hence increase in cardiovascular morbidity and mortality.
The need to score nutrition is highlighted by the fact that the nutritional status is based on multiple factors – clinical and biochemical – and the outcome is dependent on the trend of the nutritional status.
| Scoring Systems to Assess Nutritional Status|| |
Various scoring systems have been used to assess nutritional status over years to assess and monitor patients suffering from CKD and ESKD on MHD to reduce the morbidity and mortality.
SGA refers to the overall evaluation of a patient by an experienced clinician. It correlates the subjective and objective aspects of medical history and physical examination. It also satisfactorily agrees with objective methods of assessing malnutrition. Moreover, SGA is inexpensive, can be performed rapidly, requires only brief training, gives a global score of nutrition, and is reproducible. In our study, it was observed that 43 out of 81 (53%) subjects were mild to moderately malnourished by the SGA method of nutritional assessment. This correlated with the anthropometric measurements. SGA did not correlate well with diet recall. This is understandable because dietary recall is based on the patient's ability to recall his intake. Hence, it may overestimate or underestimate the protein and calorie intake. SGA did not correlate with the serum albumin levels also. This is probably due to the fact that a fall in serum albumin levels lags much behind the onset of malnutrition. It is necessary to observe the trend of nutritional status to appreciate the development of malnutrition. This may be missed by one-time anthropometric measurements and biochemical parameters. For example, a patient may be obese to start with and later may lose some weight. This will show a normal anthropometric assessment but on SGA score a deteriorating nutritional status. SGA can also be used for continuous quality improvement.
Malnutrition inflammation complex syndrome (MICS) occurs commonly in MHD patients and may correlate with increased morbidity and mortality. An optimal, comprehensive, quantitative system that assesses MICS could be a useful measure of clinical status and may be a predictor of outcome in MHD patients. It was therefore attempted to develop and validate such an instrument, comparing it with conventional measures of nutrition and inflammation, as well as prospective hospitalization and mortality. Using components of the conventional SGA, a semi-quantitative scale with three severity levels, the dialysis malnutrition score (DMS), a fully quantitative scoring system consisting of seven SGA components, with total score ranging between 7 (normal) and 35 (severely malnourished), was recently developed. To improve the DMS, three new elements were added to the seven DMS components: body mass index (BMI), serum albumin level, and total iron-binding capacity to represent serum transferrin level. This comprehensive malnutrition-inflammation score (MIS) has 10 components, each with four levels of severity, from 0 (normal) to 3 (very severe). The sum of all 10 MIS components ranges from 0 to 30, denoting increasing degree of severity.,,,,,,,,,,,,
Kalantar-Zadeh et al. concluded that MIS may be superior to the conventional SGA and the DMS, as well as to individual laboratory values, as a predictor of dialysis outcome and an indicator of MICS.
Few other scores have been studied to assess the nutritional status, namely the Mini Nutritional Assessment, the score of International Society of Renal Nutrition and Metabolism, and the Objective Score of Nutrition on dialysis. The details for each can be found in the references noted in bibliography section.
Among subjective nutritional markers, combined methods for nutritional status assessment have gained prominence. These methods are based on a combination of subjective and objective elements of nutritional status, which provide a set of information about nutritional deficit condition and its level. In the context of CKD, the SGA and the MIS stand out among the combined methods employed in clinical practice and in studies.,,,,,,,,,
| Creatinine and Creatinine Index|| |
Creatinine level reflects muscle mass, but variability in excretion/clearance and change with meat intake decrease utility. A low serum creatinine (in dialysis patients) and low creatinine index (creatinine generation) suggest malnutrition and wasting of skeletal muscles. A low or declining creatinine index correlates with mortality. It is an example of reverse epidemiology.
| How Do I Assess Nutritional Status of My Patients?|| |
My assessment starts with a detailed history assessing the patient's well-being followed by a practical approach as follows.
- Weight change over the past 6 months
- <5% weight lost
- 5%–10% weight lost
- 10% weight lost.
- Usual intake
- Less than usual
Loss of subcutaneous fatMuscle wasting, BMIBiochemical parameters
- Serum albumin
- Total iron binding capacity (TIBC)
- Serum creatinine and index.
| Summary|| |
PEM inflammations are common complications of CKDs and ESKD patients on dialysis. These are associated with increased morbidity and mortality in patients suffering from CKD and those with ESKD on maintenance dialysis. An appropriate diet is required at each stage of kidney disease based on the comorbidities. A simple and systematic approach to assessing the nutritional status and monitoring the nutrition on serial clinical follow-up is important. It is important to recognize that nutritional status is to be assessed as a trend rather than a one-time assessment.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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