Renal Diet
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Introduction
Diet is perhaps 50% of the management plan for people with kidney disease, and a renal-friendly diet both offloads the kidneys of fluid, potassium, phosphorus and protein while ensuring nutritional and metabolic requirements are met.
It is important for people to feel they have control, especially with a progressive condition such as kidney disease. Food and fluid intake is something people can have ownership of, providing a valuable sense of control.
Dietary changes are progressive, following decline in kidney function. As many people with kidney disease have hypertension, diabetes, or cardiovascular disease, low-sodium, low-cholesterol diets are very important. Low-protein intake is important initially to reduce disease progression, but high-protein intake is suggested once dialysis is begun. Phosphorus is to be reduced early on, especially to prevent later calcification. Potassium only is a problem as urinary input drops.
Dietitians role is to teach people how to cheat; how to work food they want in.
Actually, a renal diet is quite unhealthy, as people are limited in fruits and vegetables (potassium), fibre (phosphorus), legumes, (potassium and phosphorus) and dairy. Restriction of these healthy foods means sufficient calorie intake can be difficult, and patients are actually recommended to eat sugar and candies! Strict vegans can have significant difficulties.
Important parameters include:
- fluids
- protein
- potassium
- phosphorus
- supplementation
Fluids
Fluid intake increasing becomes an issue as kidney function declines.
Fluid intake should be 500 ml + urine output. For people on hemodialysis, this means only two cups of fluid daily.
Protein
Protein intake should be decreased in people with kidney disease to prevent stressing the kidney with protein metabolites. The aim should be to meet the minimum needs for metabolic health.
Pre-dialysis patients should aim for 0.6-0.8g/kg/day, instead of the normal 0.8-1.0g/kg.
On dialysis, need to increase protein intake to 1.2g/kg/day to replace losses.
Potassium
Potassium can be both high and low in kidney disease, for the following reasons:
Potassium is in every single fruit and vegetable;
- see a spike in the summer, during harvest season
60-80 mmol/day is restriction; depends on how much they pee. follow their blood
aim for blood K and
banana = 10 mmol
Phosphorus
Phosphorus intake is important due to calcium deregulation with kidney disease. Less than 1000mg is suggested for patients on hemodialysis, and less than 1200 mg for patients on peritoneal dialysis.
Fibre also must be limited, as it contains posphorus.
Benefibre contains no phosphorus. Whole flax seeds can also be used, as they pass throug undigested.
Binders
Tums or over-the-counter calcium carbonate are a first, cheapest choice of binder. However, a chest and abdominal X-ray should first be done to assess for calcification. If calcium deposits are found, these binders should not be used.
Other non-calcium options include:
- Milk of magnesia (also helps with constipation)
- Renagel (expensive: over $400/month).
- Fosrenol
Supplementation
People on dialysis lose water-soluble vitamins, which need to be replaced.
Vitamin D
As the kidney hydroxylizes vitamin D to activate it, Vitamin D is used if people have high PTH, but normal phosphorus and calcium.
Non-active ergocalciferol is OTC, but if people have kidney issues then you need active vitamin (essentially a hormone).
Resources and References
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