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DIABETIC NEPHROPATHY DIABETIC KIDNEY DISEASE -

What is it ?

The kidneys are situated on each side of the spine. Their job is to filter excess water and impurities from the blood, to form urine. After diabetes has been present for even quite a short time, the capillary filter membranes of the kidney can become damaged. After several years, these damaged membranes may allow leakage into the urine of certain proteins, which should not be there. Albumin is one such protein, and can be easily detected. Your blood pressure may also begin to rise at this time. As time goes on, the protein link increases: your blood pressure may rise further. Both the protein leak and the raised blood pressure cause further kidney damage. Swelling of your ankles may occur at this stage, because the protein levels in the blood are reduced. Eventually, the kidneys no longer filter properly, and waste products build up in the blood. This whole process usually takes years. However, in some people, the protein leak is particularly large. The kidneys can fail quite quickly, particularly if the problem is detected too late. It is worth noting that in diabetes, the capillary membranes in the retina of the eye often behave in a similar way to those in the kidney: most people with diabetic kidney disease also have retinopathy.

How does it occur ?

It is the high levels of glucose in the blood, which trigger other chemical changes in the kidney membranes. The damaged membranes then lose their ability to filter correctly. Research shows that these changes are to some extent capable of being reversed if blood glucose levels are brought back to normal, and kept there. Raised blood pressure and the leaking protein produce tiny areas of scarring within the kidney. If blood pressure is controlled, the rate of kidney damage is also much reduced.

Why does it occur ?

As with the retina, kidney damage does not occur to the same degree in every person with diabetes. Part of this variation is due to average blood glucose and blood pressure levels which you run over a period of many years: the higher these are, the greater the likelihood of nephropathy (and retinopathy). Smoking also increases the risk. There are also inherited (genetic) factors, which affect the chance of kidney damage. At present, these cannot be measured in a way which tells us, in advance, if a particular person is at risk.

Treatment Involved

PREVENTION is most important. Keeping the blood glucose below 10mmol/litre for most of the time (and below this level before meals) is something that you yourself can work towards. The HbA1c level in the blood reflects blood glucose control over the previous 10 weeks or so. This is your doctor’s way of assessing your diabetic control. Research has shown that in both type 1 and type 2 diabetes, keeping these levels at or below about 7% reduces the rate at which albumin appears in the urine by about one-third: as yet, it is not certain by how much the risk of later kidney failure is reduced. Keeping blood pressure below 130 mm (systolic pressure) and 80mm (diastolic pressure) has also been shown to reduce the rate at which albumin appears in the urine. Even in the absence of a raised blood pressure, one group of blood-pressure lowering drugs (ACE inhibitors) has been shown to improve the short-term function of the kidneys. Again, the degree to which it prevents actual kidney failure in later life is not known.

TREATMENT It is common practice to annually check the content of albumin in the urine, either with a special strip test or with a more accurate 24-hour urine collection. Once albumin is consistently present at a certain level (microalbuminuria), you are known to be at higher risk of later kidney failure. Ideal blood glucose and blood pressure control then becomes extremely important. Keeping blood pressure at or below 130/80 (perhaps even 120/80 in younger persons) by the use of blood pressure lowering drugs reduces the likelihood and severity of kidney failure. The precise benefit of ideal blood glucose control at this stage is known only for people with type 1 diabetes, in whom microalbuminuria tends to improve. It is however probably wise for anyone with diabetes to aim for the best possible diabetic control. Some doctors recommend a low protein diet: there is some research to show that this may reduce the degree of kidney damage. Swelling of the ankles due to fluid accumulation (oedema) may require the use of water-losing tablets (diuretics). Once chronic kidney failure occurs, it is usually necessary to consider dialysis (artificial kidney) treatment. Kidney transplantation may be offered to people without heart or other serious blood vessel problems. Transplantation of both the pancreas and kidney may be offered to younger patients. This usually removes the need for insulin injections. It also ensures the best possible diabetic control to protect the transplanted kidney.

After Treatment

It is important to keep regular appointments with your doctor or clinic. You may be advised to check your own blood pressure. Any loss of control of either blood pressure or blood glucose should be notified to your doctor promptly: treatment changes may be needed. In people with diabetic nephropathy, there is a higher risk of stroke, heart attack and artey problems in the legs. This is partly due to abnormally high blood cholesterol and other fat levels, which partly result from diabetic kidney involvement. Your doctor will check a blood test for this, and may prescribe both a diet and tablets to correct any blood fat abnormalities. It is worth keeping in mind, that even in the absence of cholesterol problems, ideal blood glucose and blood pressure control will also reduce your risks of stroke and heart attack: you are already at somewhat greater risk of these, simply through having diabetes. Any retinopathy which you have will also benefit from such treatment.

If Left Untreated

Your risks of developing kidney failure, retinal damage (retinopathy), stroke and heart attack would all be higher. This highlights the importance of regular medical visits, blood tests and close monitoring of your blood glucose and blood pressure levels.

Effects on Family

There is probably little that they can do to help you, except by encouragement.