How to treat and prevent protein wastage and malnutrition in chronic kidney disease?Nephrology
How can one treat and prevent protein wastage and malnutrition in chronic kidney disease? For example, are there any supplements to help alleviate malnutrition and protein wastage for patients on a low protein diet who have end-stage renal disease (not on dialysis)?
Malnutrition in patients with chronic kidney disease
Patients with chronic kidney disease can suffer from malnutrition, especially when the disease progresses to more advanced stages.
Nutritional status can be worse in patients with:
- other conditions like diabetes,
- chronic inflammation like when suffering from lupus or other inflammatory glomerulonephritis
- large amounts of proteins loss in the urine like in the nephrotic syndrome,
- other debilitating diseases like cancer, heart failure or liver failure, or
- high nutritional demands (concurrent illnesses and infections)
A healthy and balanced diet is typically recommended to patients with chronic kidney disease in early and intermediate stages (stages 1-3a).
Ideally, you should avoid:
- high sugary foods and drinks
- fatty, oily and fried foods
- salty dishes
- processed foods.
However, as the disease progresses, more and more diet restrictions are recommended, in particular in:
- sodium (ideally should be around 2 g of sodium per day or 5 g of salt per day)
- calcium (both dietary and the one prescribed as supplements) and
The type and extent of the restrictions need to be individualised to the patient's:
a) stage of the chronic kidney disease (some patients start needing restrictions at stage 3a of chronic kidney disease, but many more from stage 3b),
c) nutritional status,
d) accompanying diseases and
e) laboratory parameters
How much protein restriction is necessary?
Typically, a restriction of 0.8 g of protein per kg of body weight per day is recommended in stages 3a/3b and 4 of chronic kidney disease.
The aim of restricting protein is to:
- slow down the progression of kidney disease
- to diminish the amount of protein-derived toxins in the blood (and the symptoms derived from them) and
- to reduce the load of phosphorus contained in proteins and the consequence of its excess.
Occasionally, doctors prescribe a higher degree of protein restriction. If this is necessary, supplementation with special amino acids (keto acids) is recommended
However, taking keto acids when the protein restriction is not high (very restrictive) does not add any significant benefit to the patient, and adds to unnecessary costs.
Malnutrition and the importance of a dietitian
Unfortunately, malnutrition could be one of the down-points of protein and phosphorus restriction, especially as chronic kidney disease progresses.
Hence, advice from a dietician with expertise in renal conditions is very important.
This will enable you to strike the correct balance between obtaining adequate nourishment, and avoiding malnutrition because of excessive restrictions.
There are indeed some oral supplements and shakes that can be taken in chronic kidney disease to enhance nutrition, but a proper assessment by a dietician taking into account all the patient factors described above is necessary.
Vegetarian diets may be helpful
Some doctors and dieticians favour vegetarian diets.
This can help many patients, but not everyone is ready to become a vegetarian.
It's important that the diet you choose is one that you can sustain, as everyone has different preferences and backgrounds at the end of the day.
Your dietician will be able to advise you on how to adopt a more balanced vegetarian diet, or how to adopt a more mixed diet according to your needs (disease protection, nutrition, palatability and sustainability).
Watching your weight is important!
Avoiding excess weight is also important in patients with chronic kidney disease, as it is an important risk factor for many medical problems.
This helps to address:
- potential heart problems
- potential kidney problems. Excess weight and calorie intake will mean that your kidneys have to overwork. With time, they can get “fatigued”, and result in a faster progression to total kidney failure faster.
The recommended energy intake is around 30 to 35 kcal per kg of body weight per day.
Fluid restriction to prevent flooding of the lungs
As the disease progresses, many patients need to undergo water and fluids restriction.
This helps to prevent fluid retention and potential flooding of the lungs, as the kidney can no longer handle excess fluids.
Malnutrition in patients on haemodialysis
Malnutrition can get worse once the patients reach total kidney failure (stage 5 of chronic kidney disease) and starts haemodialysis.
The occurrence of malnutrition is associated with poorer outcomes, due to the so-called protein and energy wastage syndrome.
Protein and energy wastage syndrome is caused by:
- poor intake due to poor appetite, nausea or even vomiting accompanying total kidney failure,
- overconsumption or wastage of proteins and energy stores because of high toxins in the blood,
- the development of chronic inflammation and many accompanying diseases, or
- diet restrictions prescribed by doctors and dietitians (which are in turn necessary to avoid other complications).
It is indeed difficult to strike a good balance in many patients on haemodialysis.
How to identify patients with protein wastage?
Many patients with kidney failure can look very thin. However, overweight patients can still suffer from protein wastage.
Hence, the nutritional status of dialysis patients needs to be checked frequently (eg. every 1-3 months) by:
- asking about recent or ongoing weight loss, eg. clothing getting looser or people telling them they have lost weight (sometimes it might not be obvious to them)
- asking about new complications or accompanying illnesses. Proper treatment helps to reduce the impact on nutrition
- asking them about recent admissions to the hospital, as concurrent illness takes a big toll in the protein and energy reserves of patients
- checking for symptoms that suggest dialysis inadequacy (i.e. patient not thriving and the dialysis dose needs to be optimised)
- assessing whether chronic inflammation can be minimised
- asking them about their typical meals, but ideally with a food diary for at least one week,
- body measurements like the body mass index (the so-called BMI),
- physical examination
- laboratory tests like the serum albumin (ideally around or over 40 g/L in the blood)
- measurements of the normalised protein catabolic rate (nPCR)/protein nitrogen appearance (PNA) – a complex but useful way to calculate nutrition in the body of dialysis patients
- body fat composition scans
The role of dialysis and dietitians
Advice from a renal dietician who has experience in dialysis patients can help to further improve nutritional status.
Typically, patients are recommended to eat around 1.2 g of protein per kg of body weight per day, ideally of high biological value.
In addition, the energy intake should be around 30-35 kcal per kg of body weight per day.
All these calculations might be perplexing to most people, even to doctors.
Dieticians can help “translate” these doctors’ prescriptions into something practical. Eg: what food to buy and how to cook it, and which food to miss or moderate.
In addition, dietitians are the best professionals to help haemodialysis patients strike a good balance between restrictions and nutrition (although this is not very easy).
Many patients can benefit from prescribed oral protein and energy supplements and shakes, prepared especially for dialysis patients.
Dieticians can tell you which supplement is the right one for you, and how to take the right amount in combination with your diet plan.
Rarely, haemodialysis patients will require intravenous nutritional supplements, especially when not thriving on oral supplementation or when malnutrition is very severe.
Malnutrition in patients on peritoneal dialysis
Malnutrition is also common in patients on peritoneal dialysis.
In patients undergoing peritoneal dialysis, malnutrition occurs because of:
- increased protein and energy wastage due to high levels of toxins in the blood,
- loss of protein and amino acids into the peritoneal fluid with each peritoneal wash (peritoneal exchange), especially if the peritoneal membrane status is very absorptive
- patients not feeling hungry because of the sugar load with the peritoneal dialysis washes, or
- patients feeling full because of the dialysis fluid inside the tummy
The nutritional status in peritoneal dialysis patients also needs to be monitored frequently (eg every 1-3 months).
This is similar to the monitoring of patients on haemodialysis. The transport status (with the use of the peritoneal equilibration test) needs to be assessed and monitored for changes across time.
Once more, seeing a dietician with experience in peritoneal dialysis patients is crucial.
The protein intake recommendation is similar to the one for haemodialysis patients, at around 1.2 to 1.3 g of protein per kg of body weight per day. It's ideal to adjust the calories intake to the amount of sugar contained in the peritoneal dialysis washes.
Finally, there are commercial peritoneal dialysis solutions with amino acids with the aim of both minimising the load of sugar per day, but to provide the patients with amino acids to build protein in order to enhance their nutrition.
I hope this information is useful for you. This is a complex and very important matter, so I recommend you to discuss this further with your favourite nephrologist and an experienced dietician. They can assess you properly and decide whether you need a specific diet.
Dr Francisco, wishing you the best possible health.
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