Role of Uric Acid in Dialysis

nephroplus | April 22, 2020

Uric acid is a normal body waste product. It forms when chemicals called purines break down. In healthy individuals, Kidney excrete 70% of uric acid from the body. Hyperuricemia is often observed among obese individuals, diabetic or hypertensives , and has been associated with cardiovascular disease and mortality mainly in the general population.

Dietary intake of purines and fructose is a primary source of uric acid, and so levels could vary with nutritional status.

The major source of uric acid

Purine-rich foods such as meats, seafood and purine-rich vegetables like soy, palak, peas, mushrooms

Fructose source- Sweeten processed foods, breakfast cereals, bakery foods, beer and  soft drinks

Uric Acid In CKD

In CKD patients, the efficiency to remove waste product like uric acid declines, leading to high serum uric acid.  Most studies have  stated  that an elevated serum uric acid level is a risk factor for  development of CKD. Patients with hypertension, metabolic syndrome and chronic kidney disease frequently have elevated uric acid levels which is associated with cardiovascular risk.

Uric acid in hemodialysis

The results show that improving the efficiency of dialysis may improve the quality of life and reduce the complications in patients, but it does not help to control uric acid level. It is better to apply other modalities such as medical therapy or special diets or changing lifestyle to control it.

High uric acid concentrations is associated with high protein intake or high normalized protein catabolic rate (nPCR) (Formula used to assess dietary protein intake in dialysis patients to check for their nutritional adequacy). High uric acid is also associated with  greater BMI, and higher serum concentrations of albumin, creatinine and phosphorus. Uric acid concentrations may reflect patient appetite or dietary protein intake.  Low  uric acid indicates poor nutritional status and hence higher mortality.

Sometimes, it does happen that patients having regular intake of good quality proteins like lean meat, fish, egg whites, low fat dairy products may have low serum uric acid . This may be because of the low to moderate purine content of the food. Even if the patients has low uric acid  and high nPCR they are considered to be well nourised  and hence have lower mortality.

Hemodialysis patients  are exposed to various oxidative stress.Uric acid has antioxidant properties. This property will benefit hemodialysis patients, where oxidative stress is more. Oxidative stress is a risk factor for cardiovascular mortality .

A low purine diet is planned to help you:

  • Maintain a healthy weight and good eating habits
  • Undsterstant the purine content of food .Avoid some, but not all, foods with purines
  • Include some functional foods that can chelate and control uric acid levels like cherries, apple, cucumber etc

A good rule of thumb is to choose low to moderate content of of healthy foods. Speak to your dietitian to understand the portion size of the protein foods to be taken to replenish the protein loss during dialysis and which further does not add to the purine load.

Article by: Meera Shah, Clinical Dietitian, M.Sc, CDE, RD.


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