More than 500 million people in the world have chronic kidney disease, a silent killer that creeps upon patients without them realising.

Like in other developed and developing countries, kidney disease was becoming a bigger problem in Malta, consultant physician and kidney specialist Emanuel Farrugia said.

"Locally, it is still on the increase," he said, adding that chronic kidney disease was fatal, unless treated through dialysis or kidney transplant. According to figures from the National Organ Transplant Registry, 93 patients received a kidney between 1999 and 2007. Only about half of the patients on dialysis are eligible for a kidney transplant because of other conditions that render them high risk.

The kidneys' main function is removing toxins and excess water from the blood. Kidneys, roughly the size of fists, also help control the blood pressure, produce red blood cells and keep bones healthy.

Dr Farrugia said the underlying cause for kidney malfunction in almost half the people who started dialysis was diabetes, which was also a major determinant of the disease's progression. High blood pressure was another contributor to kidney disease.

It is estimated that 72,700 people in Malta suffer from high blood pressure and 30,000 suffer from type 2 diabetes. More than 200 patients are receiving treatment at Mater Dei Hospital's Renal Unit.

Chronic kidney disease is a progressive illness that cannot be reversed, although it might be possible to stop it advancing. It is classified as stage five - the highest stage - when the combined function of both kidneys is less than 15 per cent, making dialysis a necessary life-saving therapy.

Most sufferers are over 50, although it is not unheard of to have patients in their 20s.

"Kidney disease is a silent condition in the majority of cases, so it is not unusual to have patients who present themselves with very advanced kidney disease who need immediate treatment," he said.

In fact, one of the messages of this year's World Kidney Day, marked today, is to ensure early diagnosis through regular screening.

Although Dr Farrugia said it was impossible to screen the whole population, all those over 50 needed to have regular blood and urine checks. Diabetics, who suffer from high blood pressure, smokers and people with a family history of kidney disease, should also get screened, irrespective of their age.

"Smoking, like high blood pressure, accelerates the rate of kidney decline," he said, adding that there were people who had the risk factors and still did not check their kidneys to ensure any problems would be controlled.

Driving blood pressure down through certain medications could go a long way to help control kidney disease from advancing, something which is very important because there was no reversing the condition once it had advanced.

Controlling the early stages of kidney disease was imperative because the condition was associated with a much higher rate of heart attacks and stroke, conditions that were even more likely to occur than the patient progressing to stage five chronic kidney disease, Dr Farrugia added.

Obesity, an unhealthy diet and a sedentary lifestyle compound the problems, making a person more likely to suffer from diabetes and high blood pressure, which could, in turn, lead to chronic kidney disease.

Risk factors for kidney disease

• High blood pressure

• Diabetes

• Being overweight

• Smoking

• Over 50-year-olds

• Family history of kidney disease

• Other kidney diseases