With so many potential causes and a high probability of the loss of sufferers' livelihood, renal disease is one condition insurers are seemingly not keen on covering, as Wendy Hickman writes.
Most people are born with two bean-shaped kidneys, each consisting of roughly a million tiny structures called nephrons that filter the blood by removing water products and excess water, which is then excreted from the body through urine. Renal disease, where the body is unable to remove waste products, occurs if the nephrons are damaged, leading to 60% of renal function being lost. The disease usually occurs slowly, developing over a period of years.
Damage to the kidneys can be classified either as acute, chronic or end-stage disease.
Acute renal disease, also known as acute kidney disease, develops in view of an underlying disorder directly affecting the blood supply to or urine flow from the kidneys. It is usually rapid, occurring over hours or days. In most cases it is reversible and does not cause permanent damage. With appropriate treatment for the underlying disorder, a complete recovery can usually be made.
However, in some cases, acute renal disease can progress to chronic renal disease or be secondary to diabetes or high blood pressure. Chronic renal disease is usually a permanent loss of kidney function. This can progress over months or years, is usually irreversible and can be classified as either mild, moderate, severe or end-stage renal disease.
With end-stage renal disease, the kidneys are permanently functioning at less than 10% and without dialysis or renal transplant the condition is fatal.
The following conditions, if uncontrolled, can lead to renal disease:
n The presence of microalbuminuria in urine is suggestive of diabetic nephropathy in patients with type 1 and type 2 diabetes.
n Uncontrolled hypertension.
Other causes of renal disease include:
n Glomerulonephritis - a group of disorders rather than a single entity, it refers to diseases resulting in damage and inflammation of the filtration system of the kidneys, which can cause kidney failure.
n Polycysitic kidney disease - where both kidneys have multiple cysts.
n Atherosclerosis - clogs and hardens the arteries leading to the kidneys, may cause ischaemic nephropathy.
n Obstruction of the flow of urine either by stones, enlarged prostate, strictures (narrowing) or cancers.
Symptoms of acute renal disease may include fatigue, loss of appetite, nausea, frequently passing urine and numbness in the feet or hands (peripheral neuropathy). For chronic renal disease there are, however, usually no symptoms in the early stages and it can only be identified through laboratory tests.
These tests include urinalysis, blood tests and ultra-sound scan of the kidneys. The ultra-sound scan for acute renal failure will show a normal-sized kidney, whereas chronic renal disease may show an increase in size (due to diabetes, polycystic kidney disease, myeloma, and amyloidosis) or a reduction in size (due to other forms of disease). The scan will also be able to show whether there is any other obstruction in the urinary flow indicating renal stones. The scan will also assess the amount of blood flow going into the kidneys. If the symptoms are unclear then sometimes a biopsy is performed.
Treatments for renal disease depend on the underlying cause and can focus on slowing down or halting the progression, treating the underlying cause and associated factors or trying to replace lost kidney function. In end-stage renal failure, the kidney function can only be replaced by dialysis or transplantation.
The outcome of acute renal failure depends on whether the underlying cause has been identified early enough to eliminate any permanent renal damage and tend to have a good prognosis. On the other hand, for chronic renal failure, there is no known cure. The only choices at this point would be to slow down or halt the progression. Chronic renal disease will inevitably progress until dialysis or a transplant is required.
Patients with chronic kidney disease are at a much higher risk of developing strokes or heart attacks compared to the general population.
People undergoing dialysis have an overall five-year survival rate of 32%. The elderly and those with diabetes have worse outcomes.
Recipients of a kidney transplant from a living related donor have a two-year survival rate greater than 90%.
Recipients of a kidney from a donor who has died have a two-year survival rate of 88%.
How many people have acute renal failure?
Relatively little is known about the numbers of people who develop acute renal failure, and analysis of the evidence is complicated by varying definitions of the condition. In recent studies, those treated for acute renal failure ranges from 209 to 545 per million population. It is clear, however, that the number of acute renal failure cases has risen over the last 15 years, and is more frequent in older people and in those with existing illnesses, particularly cardiovascular disease.
The incidence of acute renal failure in children in the UK, based on referral to regional paediatric renal units, is estimated to be 7.5 per million population a year. The true incidence is likely to be greater as some children with acute renal failure who do not require extra-corporeal therapy are managed by general or non-renal specialist paediatricians.
Chronic kidney disease
Recently, international studies have begun to focus on the true prevalence of chronic kidney disease in the population. A survey of blood samples carried out in the South East of England in 2001 found the prevalence of diagnosed chronic kidney disease to be 5,554 per million population. A large screening study carried out in the US showed that as many as 5% of adults are in stages three to five of chronic kidney disease, and another 5% may have stage one or two chronic kidney disease. However, this may be an over-estimate of prevalence as it was based on a single measure. Of those in stages three to five, two-thirds were over the age of 70, while a quarter were known to have diabetes and three-quarters had a history of hypertension.
For older adults, as with small children, a slightly reduced level of kidney function is normal. People with an estimated glomerular filtration rate (kidney function measurement) of more than 60, but with no structural abnormality or any other evidence of kidney disease, are not considered to have stage one or two chronic kidney disease, and there is no evidence that they have a higher risk of developing chronic kidney disease or complications such as anaemia or bone disease. n
Wendy Hickman is life and disability underwriter at Aegon Scottish Equitable
Sources
www.emedicinehealth.com
www.dh.gov.uk
