Doctors are warning of the dangerous link between excessive body fat and kidney disease.

People who are overweight or obese often have several risk factors for the malady, including high blood pressure and diabetes, they point out.

High blood pressure damages the tiny blood vessels in the kidneys that filter waste and excess fluid from the blood. The persistently high blood sugar levels characteristic of diabetes also damage the vessels.

“Diabetes and high blood pressure are responsible for 20% to 30% of all chronic kidney disorders,” says Dr Mark Dominik Alscher, president of the German Nephrology Society.

Besides filtering the blood, the kidneys produce urine and help to regulate blood pressure, among other things. But most people never notice they even have these vital organs, located under their lower ribs, even when they’re diseased.

Since kidneys have few pain-conducting fibres, they don’t induce symptoms themselves, in stark contrast, for example, to the heart during an infarction.

Herein lies the danger.

According to a study by a team led by Dr Matthias Girndt, a kidney specialist at Halle-Wittenberg University Hospital in Germany, fewer than one in three Germans whose kidneys aren’t functioning properly are aware of it.

Alscher says scientists have found that obesity also harms the kidneys directly via inflammatory processes in the fatty tissue. The gradual loss of kidney function proceeds for 10 to 15 years on average, he notes.

Barring treatment to halt the damage, dialysis – or artificial filtering – becomes necessary just a few years later, generally when kidney function has dropped to under 10%.

Kidney damage isn’t reversible, and chronic kidney disease can lead to end-stage kidney failure, which is fatal without dialysis – an expensive and time-consuming procedure – or a kidney transplant, for which there’s a shortage of donor organs.

Many kidney patients previously died before being sent to dialysis, Alscher says.

He adds that people as young as 20 or 30 years of age now develop type 2 diabetes – formerly known as adult-onset diabetes – which is much earlier than in the past.

“These people then undergo dialysis between the ages of about 30 and 45,” he remarked.

Kidney specialists also paint a dark picture in view of the large numbers of overweight and obese children today compared with earlier generations.

“This is a great danger. I’m very concerned about it,” Girndt said. “Someone who is obese as an adolescent rarely achieves a normal weight.”

Alscher says between 8% and 15% of the populations in Western industrialised countries already suffer from kidney disease – and the numbers “will increase”.

Girndt’s study is one of the few on the prevalence of impaired kidney function. Using data gathered in 2008-2011 by the Berlin-based Robert Koch Institute, responsible for disease control and prevention, it estimates that at least two million people are affected in Germany alone. Many of them are unaware of their condition and therefore don’t have it treated.

“We nephrologists are considering how to detect it sooner,” Alscher said, noting that early-stage kidney disease is discovered “only by chance”.

While many people are aware of the health significance of cholesterol levels, creatinine levels – an indicator of kidney function – are largely unfamiliar.

Since diagnoses of kidney disease are often made late, affected persons generally already have numerous secondary diseases that often occur simultaneously.

They can involve the cardiovascular system, lungs and bones, for example.

If treatment begins early enough, doctors now are fairly confident they can slow the disease’s advance with medications, Alscher says.

To facilitate early detection, Girndt underscores the importance of examining kidney function when a person has a family history of diabetes, is overweight or has high blood pressure.

“We should take this group of diseases considerably more seriously and increase public consciousness of the importance of measuring creatinine levels as well as those of cholesterol,” Alscher said, pointing out that the most inexpensive testing method costs just pennies. – dpa