Kidney disease is recognized as a common complication of diabetes mellitus (DM), with as many as 30 percent of patients with DM having this complication. Here are seven pointers to prevent its progression to end stage kidney disease
BY MA. ISABEL D. DUAVIT, MD
The kidneys are important because they remove waste products from the body by filtering blood and producing urine. In addition to removing drugs and toxins, they also balance the body fluids, release hormones that control blood pressure, regulate salts(sodium, potassium, phosphorus, calcium), promote production of red blood cells, and keep the bones healthy.
Chronic kidney disease (CKD) is defined as having some type of kidney abnormality such as presence of protein in the urine, and/or having decreased kidney function for three months or longer. If one’s kidney disease is caused by diabetes, then one’s doctor will give a diagnosis of chronic kidney disease secondary to diabetic kidneys (formerly known as diabetic nephropathy).
Kidney function tests
CKD may be a silent disease, and early kidney disease rarely has symptoms. Generally, diabetic kidney disease is considered after a routine urinalysis and screening for microalbuminuria in the setting of diabetes. Laboratory testing using either serum creatinine or the presence of albumin in the urine have been recommended screening measures. With these tests, your doctor can tell how well your kidneys are working:
1. Urine albumin or albumin-creatinine ratio (UACR)
This is a sensitive urine test that can detect small amount of protein (known as microalbuminuria) long before there is evidence of kidney disease in the usual blood tests. Protein is not normally found in the urine. When the kidneys are damaged, protein spills from blood into the urine. Microalbuminuria is defined as albumin excretion of more than 20 µg/min, or albumin-to-creatinine ratio (µg/g) > 30. This phase indicates early kidney disease and calls for aggressive management at which stage the disease may be potentially reversible (i.e., microalbuminuria can regress). Persistent albuminuria is confirmed when albumin is >300 mg/d or >200 µg/min on at least 2 occasions 3-6 months apart.
Creatinine is a waste product usually removed by the kidneys from the body and eliminated through the urine. When the kidneys are damaged, creatinine levels increase in the blood. You can get an estimate of your kidney’s filtering ability by computing for your kidney’s estimated glomerular filtration rate (eGFR). It is the basis for establishing the stage of CKD. The higher the creatinine, the lower the eGFR, and the worse your kidney function is.
Kidney disease categories
Current guidelines classify CKD based on estimated glomerular filtration rate (eGFR) and albuminuria to estimate the risk of progression or associated cardiovascular or renal events(see the chart below).
More recent epidemiological evidence indicates that patients with proteinuria with higher eGFR may have greater risk for progressive loss of renal function than patients with more advanced reductions in eGFR who have little or no proteinuria. Patients with chronic kidney disease stages 1-3 are generally asymptomatic; clinical manifestations typically appear in stages 4-5.Once your GFR is known, your doctor can plan and modify treatment according to the stage of kidney disease you have.
7 pointers to prevent ESRD
Without proper treatment, the time between the start of diabetic kidney damage to end stage kidney failure (also known as end stage renal disease or ESRD) is about five to seven years. The lower your stage when you begin treatment, the greater the chances of success in trying to delay progression to a later stage. Here are the steps you need to take to prevent diabetic kidney disease progression:
1. Control your blood sugar.
In addition to capillary blood glucose monitoring(CBG), your doctor will request for a test known as HbA1c(glycosylated hemoglobin) which will indicate your blood sugar control in the past three months. Ideally, blood glucose should be maintained at nearnormal levels (premeal levels of 70-130 mg/dL and hemoglobin A1C [HbA1c] levels < 7 percent.
It is possible that more intensive blood glucose control may benefit kidney function more in people with diabetes. However, one needs to balance the potential benefits of improved sugar control on the rate of loss of kidney function with the greater propensity for hypoglycemia or low blood sugar.
Patients with kidney disease are much more likely to suffer adverse events related to hypoglycemia. It is therefore recommended that blood glucose targets should be individualized. For example, corresponding HbA1c targets may be less than 7.5 percent in an elderly patient with a coexisting chronic disease such as CKD(chronic kidney disease) or even higher such as 8 percent or more in patients with very poor health and decreased life expectancy.
2. Control blood pressure.
For people with diabetic kidney disease, lowering blood pressure to less than 140 mm Hg systolic is associated with a significant reduction in the incidence of kidney failure. However, just like sugar control, current guidelines recommend individualized blood pressure targets. A goal of less than 130/80 mm Hg, for example, may be beneficial, especially if there is protein in the urine.
Your doctor will probably give you a high blood pressure medication that blocks the renin-angiotensin system known as ACE (angiotensin converting enzyme) inhibitor or an ARB (angiotesin receptor blocker) since studies have shown that these medications can decrease protein in the urine and retard progression of kidney failure. Evidence exists that employing these drugs and lowering blood pressure to approximately less than 140 mm Hg systolic is associated with reducing your risk to develop end stage kidney failure) by25 to 28 percent.
3. Take all your medicines regularly.
Although the most effective way of slowing the loss of kidney function is by controlling blood sugar and blood pressure, focusing on them alone does not provide adequate treatment for patients with diabetic kidneys. CKD is not a single process that can be reversed by just improved blood pressure and sugar control. A variety of therapies will be required to target the many factors that affect disease progression.
High cholesterol, for example, can cause blood vessels to become clogged and further impair blood supply not only to your kidneys but also to your heart and brain. If the cholesterol and other fatty substances in your blood (known as lipids) are high, you may need to be given anti-cholesterol medications called statins to lower them.
If vitamin D levels are low, you may be given vitamin D supplementation. If there are already complications of kidney disease such as acidosis, increased phosphorus (hyperphosphatemia), and anemia, you will be given medications to minimize the complications and slow the rate of progression of your kidney disease.
4. Follow your diet.
Recent studies have indicated that a healthy diet is associated with a reduced risk of developing CKD and slower progression of early kidney disease among individuals with type 2 diabetes. A diet with significant amount of fruits and vegetables, moderate amounts of saturated fat and simple sugars, low amount of salt, and reduced amounts of protein may be helpful.
Protein intake recommendations range from 0.6-0.8 gram per kg of body weight. However, reduction in protein intake is not recommended for everyone and you need to discuss with your doctor regarding the diet that is best suited for you.With advancing renal disease, protein restriction may be as much as 0.8-1 g/kg/d and the diet may also include phosphorus and potassium restriction.All diabetic patients should consider reducing salt (sodium chloride) intake at least to less than 5-6 g/d, in keeping with current recommendations for the general population, and may benefit from lowering salt intake to even lower levels. A recent study demonstrated that a low-sodium diet enhanced the kidney and heart protection effects of blood pressure medicine angiotensin receptor blockers (ARBs) in type 2 diabetic patients with nephropathy.
5. Get regular exercise and target ideal body weight.
No restriction in activity is necessary for persons with diabetic kidneys, unless warranted by other associated complications of diabetes. It is recommended to have exercise training of more than 150 minutes per week. Older patients or patients with evidence of atherosclerotic disease should have a cardiovascular evaluation and clearance prior to initiating an exercise regimen.
It is also recommended for overweight patients to lose weight because modest weight losses of 5-10 percent have been associated with significant improvements in cardiovascular disease risk factors (i.e., decreased HbA1c levels, reduced blood pressure, increase in HDL cholesterol, decreased plasma triglycerides) in patients with type 2 DM.
“Patients with kidney disease are much more likely to suffer adverse events related to hypoglycemia. It is therefore recommended that blood glucose targets should be individualized”
6. Avoid substances that can cause further kidney damage.
Once you have kidney disease, it is recommended that you check with your doctor first before taking any medicines or herbal supplements because a lot of these are metabolized by your kidneys. Nephrotoxins are substances that may further damage kidneys in patients.
Certain antibiotics and some over-the-counter medicines like pain medicines can be toxic to the kidneys, causing permanent damage. The most common pain-relieving medicines known as nonsteroidal anti-inflammatory drugs (NSAIDS) in particular can make your renal function much worse and should be avoided. Dosages of most medications(e.g. antibiotics) need to be adjusted according to the level of kidney function. You should also require clearance for certain procedures that may require use of contrast(e.g.,CT scan). You should also avoid smoking and alcohol.
7. Follow up with your doctor as often as you are told.
Regular outpatient follow-up is key in managing diabetic kidney disease successfully. With each encounter, your doctor can discuss with you goals of management including blood glucose and blood pressure targets, as well as modify your medications, diet, and exercise regimen. Regular monitoring for complications, presence of infections, and laboratory assessment are also done at this time. You may be referred to a kidney doctor (nephrologist) and a dietitian who will work along with you to make your kidneys last longer.
However, some patients with chronic kidney disease may progress to end-stage kidney failure. The rate of progression depends on the successful implementation of said preventive measures and on the individual patient. If your GFR decreases to less than 10-15ml/min (stage 5)your doctor will already recommend dialysis and/or transplant to replace the work of your failed kidneys. At this level, the kidneys are no longer able to support your body in a reasonably healthy state. In most cases when your GFR decreases to below 20, your doctor will usually advise that you arrange for a permanent access for dialysis.
Timely initiation of dialysis is important to prevent the uremic complications of kidney failure that can lead to significant morbidity and death. In diabetic patients, starting earlier is useful when water volume overload renders blood pressure uncontrollable, when the patient experiences poor appetite and weight loss or other uremic symptoms, such as severe vomiting, inability to sleep or too much sleeping, progressive weakness, occurrence of seizures and spontaneous bleeding. Refusal of dialysis which is the treatment for uremia, may lead to a progressive decline in general health and ultimately leading to death.
According to the Philippine Renal Disease Registry in 2011, diabetes was responsible for 42 percent of all end-stage renal disease (ESRD) cases who were started on dialysis in our country. Except in patients with severe complications, renal transplantation should also be considered because it offers the best degree of medical rehabilitation in patients with uremia and diabetes. This option must be discussed early on with the patient and his or her family. Transplantation even before dialysis (preemptive transplantation) is becoming increasingly popular in some centers. Preemptive transplantation can be considered when eGFR decreases to below 20.
Diabetes is the leading cause of chronic kidney disease in the Philippines. Having diabetes does not always mean your kidneys will fail. Regular screening and outpatient follow-up is important in managing diabetic kidneys. Ensuring optimal glucose control, optimizing blood pressure, and treating other associated complications of diabetic kidneys are also crucial. If these steps are not taken to slow the worsening of kidney function, the kidneys may eventually fail, and either dialysis or kidney transplant would be needed to live.
ABOUT THE AUTHOR:
Maria Isabel de Leon Duavit, MD is a clinical associate professor at the UP-PGH Medical Center and a Nephrology consultant, at the UP-PGH, Asian Hospital and Medical Center, Las Pinas City Medical Center, and Medical Center Paranaque. She is the Medical Director of Kobe Dialysis Unit and Bbraun Avitum Dialysis Center at Alabang, Muntinlupa