Kidney patients warned away from potassium

Many kidney failure patients are increasing their chance of nerve damage in their legs and feet by simply having too much potassium in their diet, according to research carried out by the University of New South Wales (UNSW), the Prince of Wales Medical Research Institute (POWMRI) and the Prince of Wales Hospital.

The researchers found that high levels of potassium, which is found in foods such as bananas and peanuts, is responsible for causing nerve damage in these patients, which in extreme cases can lead to people being forced to use a wheelchair.

One in three Australian adults have an increased risk of developing kidney disease, which is commonly caused by diabetes. In end stage kidney disease, the kidneys function at less than ten percent of normal capacity and cannot sustain life of the patient without dialysis or a kidney transplant. 52,000 Australians have severe kidney function impairment or kidney failure (Kidney Health Australia).

“The majority of people with end-stage renal failure have nerve damage, in their legs and arms. This can mean they have difficulty walking or in feeling their feet,” said Dr Arun Krishnan, a Neurologist and PhD candidate in the Faculty of Medicine at UNSW. “Once nerve damage develops, it cannot be reversed unless the patient undergoes renal transplantation. But our research indicates that patients do have some control over their situation.

“We found that higher levels of potassium in renal failure patients cause that nerve damage,” said Dr Krishnan. “The clear health message is that anyone with kidney failure or chronic kidney problems should regulate their intake of potassium in an attempt to preserve nerve function.”

Potassium is found in foods such as bananas, peanuts, soybeans, apricots and sultanas.

The research Sensory nerve excitability and neuropathy in end stage kidney disease has just been published in the Journal of Neurology, Neurosurgery and Psychiatry.

“Scientists have known for a long time that potassium was an important substance in terms of regulating nerve function, but until now no-one has made the connection between kidney function and nerve function,” said co-author UNSW Associate Professor Matthew Kiernan, a neurologist based at the Prince of Wales Hospital.

“Until now, kidney specialists have been less concerned about higher levels of potassium amongst these patients, unless they were affecting the heart,” said Professor Kiernan. “The clear message is that potassium levels need to be monitored in terms of nerve function too.”

The other authors are R K S Phoon, B Pussell and J Charlesworth, all from the Department of Nephrology at the Prince of Wales Hospital.

The research was supported by the Australian Association of Neurologists Research Fellowship and the NHMRC. Grant support from the Brain Foundation, the Sylvia and Charles Viertel Charitable Foundation and the Ramaciotti Foundation.