Bleeding gums could be a sign of deadly kidney disease, new research has found. 

As many as one in two adults in Britain suffer some form of gum disease - which can present as anything from swollen and red gums, to bleeding when brushing teeth. 

The condition is usually caused by poor oral hygiene, when a build up of dental plaque hardens and irritates the gums, causing inflammation and irritation. 

But experts now believe gum disease could be a sign of something more serious. 

Examining the dental records of more than 6,000 people in Hamburg, a group of German researchers found a disturbing link between severe gum disease and the early signs of kidney impairment. 

Just 14 per cent of study participants with normal kidney function had severe gum disease. 

But of those with moderately reduced kidney function, this number shot up to more than 35 per cent. 

The findings join a growing body of evidence that suggests oral health may play a broader role in overall health than previously recognised.

Previous research has linked the chronic inflammation caused by gum disease to a number of other serious health conditions - from heart disease to diabetes. 

The latest findings, published in the International Journal of Oral Science, tracked the kidney health of 6,179 participants from the Hamburg City Health Study, a population-based cohort in Germany. 

All participants first underwent a detailed dental exam, to check for signs of gum disease. 

They then had their kidney health analysed, with tests looking for chronic inflammation. 

The results were striking. Researchers found a consistent link between poor gum health and worsening kidney function. 

People with higher levels of albumin - a protein that can leak into the urine when the kidneys are damaged - were more likely to have advanced gum disease.

And other measures of long-term oral damage, including tooth loss and destruction of the tissues supporting the teeth, also became progressively worse as kidney health declined.

Importantly, the relationship remained even after researchers accounted for well-known risk factors including age, sex, diabetes and smoking - meaning the link cannot simply be explained by people with poor overall health being more likely to develop both conditions.

Scientists say they believe chronic inflammation may be one reason why the two diseases are connected.

People with both poor gum health and declining kidney function were found to have higher levels of proteins in their blood that can indicate inflammation in the body.

But the research team agreed that high levels of inflammation couldn't entirely explain the phenomenon.

Instead, they theorised, the link could also be due to bacteria in the mouth travelling through the bloodstream to other parts of the body - including the kidneys. 

Because chronic kidney disease rarely causes symptoms in its early stages - often referred to as a 'silent' condition - identifying cases early remains difficult. 

Symptoms usually only begin once significant damage has been done to the organ, and include fatigue, swollen ankles and feet, foamy or blood-tinged urine and dry, itchy skin.

Without treatment, the condition can cause irreversible damage, and eventually, kidney failure. 

But researchers say they hope their findings could one day help doctors catch cases earlier. 

'By demonstrating an association between periodontitis and markers of early kidney dysfunction, this study highlights oral health as a potential window into kidney health,' said Dr Ghazal Aarabi, professor at the University Medical Center Hamburg-Eppendorf.

Between 40,000 and 50,000 Britons die each year from chronic kidney disease - while one in ten adults are estimated to be living with some form of the condition. 

Smoking, high blood pressure, heart disease and a family history of the condition are all significant risk factors.