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Feature Article: Addressing the Nutritional Challenges of Renal Disease

  By Amira Burnieh, Student Dietitan, Kings College London
 

Every year World Kidney Day reminds us of the global challenge of kidney disease and the importance of good kidney function for health and wellbeing. Prevention and early detection of kidney disease are important allowing for lifestyle and nutritional interventions to help delay progression of the disease. Good diet and hydration as well as a healthy weight helps to reduce the risk of kidney disease. Dietary intake of salt is also an important factor particularly when there is hypertension.

It is estimated that 850 million individuals are impacted by the different types of kidney disease with up to 1 in 10 adults having chronic kidney disease (CKD), which is mostly progressive, long-term, and irreversible (Li et al., 2020). CKD is anticipated to become the fifth most common cause of death worldwide by 2040. In contrast acute kidney injury (AKI) is usually associated with a sudden drop in blood flow to the kidneys as might occur with sepsis, heart failure, severe dehydration or blood loss. Certain medication may also increase the risk of AKI. Of topical interest is AKI in hospitalised COVID-19 patients with a suggested incidence of 29% (Malha et al., 2020).

This article raises awareness of some of the nutritional challenges those with kidney disease can experience and highlights some relevant guidelines for healthcare professionals.

 

Nutritional Challenges of Kidney Disease

Kidney disease can result in significant nutritional problems. The kidney is central to many metabolic and nutritional processes including excretion of waste products, hormone production, vitamin D activation, electrolyte homeostasis, fluid regulation and acid-base balance.  Common symptoms of kidney disease include poor appetite, weight loss and nausea increasing the risk of malnutrition. Patients may also experience a greater loss of adipose tissue and muscle as kidney function declines. Muscle wasting is more likely in those receiving dialysis or with end-stage CKD and may reflect malnutrition, sarcopenia or cachexia (Sabatino et al., 2020). Diagnosis of these nutritional conditions is important, as they are associated with increased morbidity and mortality and reduced quality of life. Recent recommendations advise that all patients with CKD who are admitted to hospital are routinely considered at risk of malnutrition (Fiaccadori et al., 2021).

 

Dietitans and Kidney Disease

The specialist renal dietitian is a core member of the multidisciplinary team with the British Dietetic Association (BDA) describing this role as to,  

…educate and empower people with any kind of kidney condition to make the food and drink choices that support health.

With no single “marker” for nutritional assessment consideration of a range of factors is needed to build a picture of a patient’s nutritional state and requirements. Whilst weight is a common measure this needs to be used with caution in renal patients due to the risk of oedema. As such distinction between “wet” weight and “dry” or “oedema-free” weight is made in renal disease. Assessments and calculation of nutritional requirements should use a “dry” or “oedema-free” weight. Lahner (2019) provides further detail on estimating dry weight in renal disease as well as patients with ascites or limb amputation. Thus weight in kidney disease is not straightforward and should be interpreted with care.

Other anthropometric measurements are used to help assess body composition and identify nutritional risks. A measure to assess risk of sarcopenia is handgrip strength whilst mid-upper arm circumference can be helpful to identify risk of malnutrition. Both of these are particularly useful in patients with oedema. Dietitians may also consider skin integrity, condition of hair, nails and the tongue, bowel function and urine colour as part of their assessment. These can be useful to help identify possible micronutrient deficiencies, absorption or digestion problems and hydration. Nutritional assessment also includes consideration of appetite and symptoms affecting this, adequacy of energy and nutrient intake, diet history, personal circumstances, food preferences and availability. Information is also required about the stage and type of kidney disease, biochemistry, co-morbidities, medication and if used any nutrient losses in the dialysate. It can be seen that nutritional assessment is far more than simply screening for malnutrition risk.

With no “one diet” for renal patients the dietitian formulates an individualised plan following assessment. Dietary changes for renal patients can be complex and may include advice to restrict fluid, salt, potassium and phosphate intake. Achieving adequate intake of energy and protein as well as micronutrients can be difficult and oral nutritional supplements (ONS) or enteral tube feeding may be required alongside diet. Sometime ONS or enteral tube feeds low in electrolytes or fluid are necessary. Conversely weight management advice may be needed for obese patients particularly if kidney transplant is being considered. Nutritional needs are also likely to change with resolution of AKI, progression of CKD or changes in treatment. Therefore careful monitoring of nutritional intake, review of nutritional status and nutritional assessment are important to inform any dietary changes or modification of nutrition support plans.

 

 
Guidelines to Support Clinicians working with Patients who have Chronic Kidney Disease or Acute Kidney Injury
 
 
 

 

COVID and Renal Disease

The BDA recommends that every COVID-19 patient admitted for hospital treatment should have their risk of malnutrition assessed, with nutrition plans communicated between care settings to ensure ongoing nutritional care. Experience has shown that COVID-19 particularly in hospitalised patients is often associated with malnutrition and risk of sarcopenia and cachexia. This is due to reduced nutritional intake, catabolic changes, inflammatory response, reduced mobility or prolonged immobilisation if sedated and ventilated (Arkin et al., 2020). Those with CKD may already be at risk of these nutritional complications, with COVID-19 exacerbating these further. There is also the risk of AKI in some COVID-19 patients with nutrition support and dietary modifications likely needed.

 

Conclusion

As healthcare professionals we can all play a part in promoting healthy lifestyle and dietary choices to support good kidney function. We all need to be aware that people with kidney disease may experience a range of nutritional complications and are at risk of malnutrition and sarcopenia. The dietitian is a core member of the renal multidisciplinary team and focused on supporting patients to follow individualised nutrition plans to maximise health, kidney function and wellbeing.

Let's work together to raise awareness of kidney disease and support people who live with it!