There is an epidemic of type 2 diabetes mellitus (T2DM) in Malaysia. The National Health and Morbidity Survey in 2006 showed that 14.9% of adult Malaysians above the age of 30 years have diabetes.
One of the most devastating complications of T2DM is renal disease, causing end-stage renal failure. These individuals with diabetic kidney failure will eventually require dialysis or kidney transplantation.
In a review of diabetic kidney failure as the reason for dialysis carried out in 2003, Malaysia unfortunately was the country with the highest percentage of diabetic people going on dialysis.
With the availability of dialysis centres, people with renal failure die of heart disease, not kidney failure.
The urine connection
Microalbuminuria is the presence of microscopic amounts of albumin in the urine.
Normally, there is no albumin present in the urine. The glomerulus in the kidney acts like a filter, allowing smaller-sized particles like water to pass through, while larger-sized particles like albumin are retained and not lost in the urine.
It is important to check for microalbuminuria because it predicts the future increased risk of renal disease, as well as heart disease.
Recognising this high risk, people with T2DM should routinely be screened for albumin in the urine.
At the stage of microalbuminuria (early diabetic nephropathy), aggressive treatment of both blood pressure and glucose has been shown to successfully reverse this condition back to normal, and this will lower the risk of progression to kidney failure and risk of heart disease.
If not treated, microalbuminuria will progress to macroalbuminuria (large amounts of albumin in the urine), and subsequently, renal damage, impairment and kidney failure.
Once there is macroalbuminuria, the onset of renal failure is inevitable.
The first screening test should be a urine dipstick looking for proteinuria, which can be performed in most clinics. This method detects large amounts of albuminuria, ie >300 mg/litre.
If the urine dipstick test is negative or has trace proteinuria, the next step is to test for microalbuminuria.
There are three main methods to screen for microalbuminuria:
·Albumin-to-creatinine ratio in a random spot urine sample
·24-hour collection for albumin/protein
·Timed urine collection over either four hours or 12 hours overnight
The albumin-to-creatinine ratio in a spot urine sample is the most convenient and simplest method.
Take note that certain conditions may cause transient albuminuria, and this does not mean the presence of diabetic kidney disease (false-positive). These include:
·Poorly controlled hypertension
·Urinary tract infection
When any of the above conditions are present, delay checking for albuminuria until the conditions are properly treated and controlled.
If the first test for microalbuminuria is positive, a second test is required within the next three months, and the result has to be persistently positive before the diagnosis of early (incipient) diabetic kidney disease is confirmed.
Managing the condition
Knowing the strategies to manage microalbuminuria can prevent progression to more severe diabetic renal disease and kidney failure, as well as reduces the risk of heart disease.
Poor blood pressure control accelerates kidney damage. Therefore, controlling hypertension to appropriate targets is very important. The recommended target is less than 130/80 mmHg for hypertension in people with diabetes.
For those with a lot of protein in the urine, measured as more than 1 gm/day, the target is bood pressure less than 125/75 mmHg.
In the management of hypertension, non-pharmacologic strategies are important and need to be emphasised. These include diet modification, reducing salt intake, and losing weight for those who are overweight/obese.
Salt restriction lowers blood pressure, and excess salt intake reduces the effectiveness of some blood-pressure medications (ACE-inhibitors and ARBs).
Use of specific anti-hypertensive drugs that block the renin-angiotensin-aldosterone system such as angiotensin-converting enzyme inhibitors (ACE-inhibitors) and angiotensin-receptor blockers (ARBs) have been conclusively shown in many studies to have beneficial effects on both the kidney and the heart.
These drugs not only lower the blood pressure, they protect the kidneys directly by decreasing the pressure inside the kidney (intra-glomerular pressure).
In many patients, more than one blood pressure medication needs to be taken to achieve the target blood pressure.