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Dietary intervention

Dietary intervention

I. Hyperkalaemia in the Community (Guidelines Hyperkalaemia 5.1–5.2)

Guideline 5.1 – Dietary Intervention for managing Hyperkalaemia in the community

We recommend that dietary strategies to modify potassium intake is instituted for patients with CKD and persistent hyperkalaemia with a serum K⁺ > 5.5 mmol/l after non dietary causes of hyperkalaemia (constipation, acidosis and poorly controlled diabetes) have been addressed. (1B)

Guideline 5.2 – Role of Specialist Dietician in managing Hyperkalaemia

We recommend that a registered or specialist renal dietician provides expert assessment and advice on dietary strategies to modify potassium intake in patients with CKD and persistent hyperkalaemia with a serum K⁺ > 5.5 mmol/l. (1B)

Audit measures

    1. Proportion of patients with moderate hyperkalaemia who have received dietary potassium advice in the renal out patient setting.

Rationale (Guideline 5.1)

Chronic management of hyperkalaemia often starts with dietary education and institution of dietary modifications, but it is important to first consider non nutritional factors and a step wise approach to reduction in dietary K⁺ intake.1 Dietary strategies to modify potassium intake should only be considered when all non dietary causes of hyperkalaemia have been excluded such as constipation, acidosis and poorly controlled diabetes. Constipation reduces K⁺ excretion by the gut and this becomes important as the ability to excrete K⁺ via the kidneys decline.

Dietary advice in adults without kidney disease

Dietary potassium comes from a wide range of foods including fruit and vegetables, meat and meat products, cereals, drinks, milk and milk products. In a standard UK diet, potatoes and savoury snacks contribute approximately 18%, meat 15%, vegetables 10% and fruit and nuts 7% of dietary K⁺ intake. WHO recommends an average dietary K⁺ intake of approximately 3.9g/day (100mmol).2 The Institute of Medicine, Food and Nutrition Board recommend a higher daily K⁺ intake of 4.7g/day (120mmol/l).3

There is some evidence that increased K⁺ intake in the general population reduces systolic blood pressure in adults with hypertension4 and may also reduce risk of stroke.5 Although a potassium rich diet has potential cardiovascular health benefits, it is not recommended in patients with advanced CKD or ESRD.1

Dietary advice in patients with CKD

The historical ‘low K⁺ diet’ is defined as a dietary intake of 2–3g/day (51–77 mmol/day).6 There is a lack of strong evidence supporting this restrictive approach,1 therefore a blanket policy is not recommended. Excessive dietary restrictions can result in a poorer diet which may risk development of cardiovascular disease7 and contribute to malnutrition, particularly in advanced CKD. In patients with CKD with persistent hyperkalaemia (serum K⁺ ≥ 5.5mmol/l), a dietary K⁺ restriction of < 3g/day (< 77 mmol/l)8 or 1 mmol/kg/IBW9 is recommended. Kidney Care UK has collaborated with the UKKA and British Dietetic Association to produce a patient information leaflet on ‘Lowering your potassium levels.’10

Fruit and vegetables are often perceived to be the main target when considering dietary K⁺ intake, but there are many less healthy sources. Importantly, processed foods containing significant levels of potassium additives are a ‘hidden’ source of dietary K⁺ intake and should be limited.11 KDIGO (2023) recommends a healthy diverse diet with a higher consumption of plant based foods compared to animal based food and a lower consumption of ultra processed foods.12

Borrelli et al (2021) studied the association between current therapeutic options and control of serum K⁺ in non dialysis CKD patients receiving nephrology care (n=562, eGFR 39.8 ml/min, RAASi 76.2%) during a 12 month period.13 Patients were stratified into four groups based on the presence of a K⁺ ≥ 5.0 mmol/l at baseline and at 12 month. During the study period, patients in all cohorts received bicarbonate supplements, K⁺ binders and diuretics. Approximately 34% of patients had either new onset or persistent hyperkalaemia despite dietary modifications and increased use of K⁺ lowering drugs.

National and International Guidelines on Diet in CKD

There are several National and International guidelines on the management of nutrition in CKD.

The UKKA (2019) Clinical Practice Guideline on Under nutrition in CKD provides guidance on screening for risk of undernutrition in patients with CKD stages 4 and 5. Assessment by a specialist renal dietitian is also advised when patients begin education about RRT and within one month of dialysis initiation.14

NICE (2021) recommend offering dietary advice about potassium, phosphate, calorie and salt intake appropriate to the severity of CKD.15 NICE has also developed a patient centred dietary resource for CKD patients of Black and minority ethnic (BME) background to improve hyperkalaemia.16

The International Society of Renal Nutrition and Metabolism and the National Kidney Foundation (2021) have collaborated to provide an update on the Clinical Practice Guidelines for nutrition in CKD.17 The new guidelines recommend screening patients with CKD stages 3–5D for nutritional status bi annually using composite scores rather than single biomarkers (e.g. albumin) and considering specialist dietetic assessment. Dietary K⁺ intake is tailored to maintain an acceptable serum level.

KDIGO (2023) recommend the use of registered dieticians or accredited nutrition providers to provide information for patients with CKD G3–G5 with emergent hyperkalaemia about dietary adaptations for potassium intake tailored to individual needs, severity of CKD, other comorbidities and quality of life.12 Some patients may also warrant pharmacological intervention.

Role of specialist dietician

Assessment by a specialist renal dietician ensures a comprehensive assessment that takes into account patient preferences, cultural dietary practices, other conditions requiring dietary adjustments (e.g., diabetes mellitus) and the need for other adjustments (e.g., phosphate, sodium and fluid intake). The importance of this specialist role is recognised in National and International guidelines in the care of patients with CKD.

The term ‘low potassium diet’ implies that there is a single regimen that applies to all and this can be restrictive. An individualised approach to dietary modifications by a specialist dietician will provide a balanced diet that meets the patient’s nutritional needs and minimises impact on quality of life.

References

    1. AlSahow, A., Moderate stepwise restriction of potassium intake to reduce risk of hyperkalemia in chronic kidney disease: A literature review. World J Nephrol, 2023. 12(4): p. 73–81.
    2. World Health Organisation (WHO). Guideline: Potassium Intake for Adults and Children; WHO: Geneva, Switzerland, 2012.
    3. Water, potassium, sodium, chloride, and sulfate. Washington, DC: National Academy of Sciences, Institute of Medicine, Food and Nutrition Board, 2004.
    4. Filippini, T., et al., The effect of potassium supplementation on blood pressure in hypertensive subjects: A systematic review and meta analysis. Int J Cardiol, 2017. 230: p. 127–135.
    5. Vinceti, M., et al., Meta Analysis of Potassium Intake and the Risk of Stroke. J Am Heart Assoc, 2016. 5(10).
    6. Cupisti, A., et al., Dietary Approach to Recurrent or Chronic Hyperkalemia in Patients with Decreased Kidney Function. Nutrients, 2018. 10(3).
    7. Khoueiry, G., et al., Dietary intake in hemodialysis patients does not reflect a heart healthy diet. J Ren Nutr, 2011. 21(6): p. 438–47.
    8. Kalantar Zadeh, K. and D. Fouque, Nutritional Management of Chronic Kidney Disease. N Engl J Med, 2017. 377(18): p. 1765–1776.
    9. Fouque, D., et al., EBPG guideline on nutrition. Nephrol Dial Transplant, 2007. 22 Suppl 2: p. ii45–87.
    10. Kidney Care UK. Lowering your Potassium Levels. Publication date: August 2023. https://www.kidneycareuk.org/order or download booklets/lowering your potassium levels/
    11. Martinez Pineda, M., A. Vercet, and C. Yague Ruiz, Are Food Additives a Really Problematic Hidden Source of Potassium for Chronic Kidney Disease Patients? Nutrients, 2021. 13(10).
    12. KDIGO 2023 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. (draft) July 2023.
    13. Borrelli, S., et al., Current Management of Hyperkalemia in Non Dialysis CKD: Longitudinal Study of Patients Receiving Stable Nephrology Care. Nutrients, 2021. 13(3).
    14. Renal Association Clinical Practice Guideline – Undernutrition in Chronic Kidney Disease. June 2019. www.renal.org/wp content/uploads/2019/06/FINAL Nutrition guideline June 2019.pdf
    15. National Institute for Health and Care Excellence (NICE): Chronic Kidney Disease – assessment and management. NICE guideline [NG203] Published: 25 August 2021.
    16. National Institute for Health and Care Excellence. Development of Black and minority ethnic (BME) patient centred dietary resources to improve hyperkalaemia in chronic kidney disease patients. Published March 2019. https://www.nice.org.uk/sharedlearning/development of black and minority ethnic bme patient centred dietary resources to improve hyperkalaemia in chronic kidney disease patients
    17. Kistler, B.M., et al., The International Society of Renal Nutrition and Metabolism Commentary on the National Kidney Foundation and Academy of Nutrition and Dietetics KDOQI Clinical Practice Guideline for Nutrition in Chronic Kidney Disease. J Ren Nutr, 2021. 31(2): p. 116–120 e1.