Your kidneys serve as a collection of tiny filter units that filter out all the toxins and waste products from your blood. Blood enters the kidneys through small blood vessels called capillaries into a complex of tiny blood vessel loops. Through these blood vessels, the blood is filtered. The blood, cleansed of toxins and waste, then reenters the bloodstream, and the waste goes through a series of tubules in the kidney and is changed into urine. Urine is then sent to the bladder for storage and removal from the body.
If you have diabetic nephropathy, or kidney disease, the capillaries become damaged and are unable to filter the blood properly. They can become blocked, so that not all the wastes and toxins are removed from the blood. They also become leaky, so that some of the proteins and nutrients that should remain in the blood are excreted into the urine.
It takes a long time for you to feel the effects of kidney damage. Nephropathy progresses through five stages: hyperfiltration, microalbuminuria, nephrotic syndrome, renal insufficiency, and end-stage renal disease. In the early stages, it just means your kidneys have to work overtime to get rid of all the toxic and unwanted products in your blood.
But as damage to the kidney progresses, they cannot keep up with the workload and eventually begin to fail. At this point, you may begin to notice the symptoms of kidney damage. Fortunately, there are tests your doctor can perform to detect the early stages of kidney disease. By paying attention to these early signs, you can take steps to prevent or delay serious kidney damage and live a longer and healthier life.
The first sign that your kidneys are damaged is that they are working overtime or hyperfiltering. If you have hyperfiltration, then a higher-than-normal amount of blood is filtered through your kidneys every hour. Hyperfiltration is quite common in the early stages of diabetes. As many as 70% of people with type 1 diabetes and 33% of people with type 2 diabetes have hyperfiltration early in the course of diabetes. However, less than 50% of people with diabetes who have hyperfiltration develop end-stage renal disease, or kidney failure.
There are no symptoms of hyperfiltration. The only way to know for sure that you have it is through tests that your doctor can do. Patients with hyperfiltration typically have enlarged kidney, a high rate of filtration of blood, and an increased rate of clearance of substances from the blood. Your doctor can evaluate whether any of these indicate that you may have hyperfiltration
What You Should Do
If you have diabetes, your doctor should be regularly evaluating your kidney function. If any tests indicate that you may have hyperfiltration, you will want to take steps to control your blood glucose levels and your blood pressure. Usually, bringing your blood glucose under control decreases the size of your kidneys and reduces the rate of filtration to within normal levels.
The best way to prevent hyperfiltration from occurring and from progressing to more serious forms of nephropathy is to keep your blood glucose levels under control. If you practice tight control, or intensive therapy, you are 35% to 55% less likely to develop kidney disease than is someone who controls diabetes using a standard approach.
Microalbuminuria occurs when small amounts of a blood protein known as albumin start to show up in the urine. People without diabetes usually excrete less than 25mg of albumin in their urine each day. But people with microalbuminuria typically excrete 30mg to 300mg of albumin per day. Microalbuminuria is often present in patients with type 2 diabetes when they are diagnosed with diabetes and usually develops in patients with type 1 diabetes after a year or more. It is important to detect microalbuminuria early to prevent further damage to the kidneys, especially if you have type 1 diabetes. Also, among people with type 2 diabetes, high blood pressure is associated with microalbuminuria. If you have type 2 diabetes and microalbuminuria, you are more likely to have a heart attack or stroke. Therefore, whether you have type 1 or type 2 diabetes, dealing with microalbuminuria early on is a good way to prevent or delay further kidney damage and to reduce the risk of heart attack, stroke or other serious conditions.
If you have microalbuminuria, you will not feel any outward signs or symptoms. The only way to know for sure if you have this condition is through a specific laboratory test conducted by your doctor.
What You Should Do
If you have had diabetes for a while or even if you are newly diagnosed, your doctor should be testing for microalbuminuria during your routine physical examinations. She will conduct a test that is more sensitive for finding protein in the urine than the routine dipstick tests you may be accustomed to. You will probably be asked to collect a specimen of urine first thing in the morning and bring it to your doctor’s office. If this test is positive, you may then be tested for total albumin content. You may be tested on more than one occasion, because the level of albumin in your urine can vary from day to day and throughout the day, depending on your activities. Once you have begun treatment, your doctor may want to retest to see if there is any improvement.
If you do have microalbuminuria, there are changes occurring in the blood vessels in your kidneys that filter out impurities. When these filters in your kidneys are damaged, protein from the blood leaks out. Blood pressure within the kidneys is also elevated and appears to contribute to the problem. Your doctor will probably advise treatment with an angiotensin-converting enzyme (ACE) inhibitor. These drugs lower blood pressure by blocking enzymes that constrict blood vessels. Lowering blood pressure within the kidney’s filtering units reduces damage to the kidney. As a result, less protein will leak into your urine. Your doctor will most likely want to continue testing for microalbuminuria on a routine basis to monitor the condition of your kidneys.
To prevent microalbuminuria and other stages of nephropathy from occurring or to delay their progression, it is important to control high blood pressure, to keep blood glucose levels under control, and to eat a balanced diet. Preventive measures are extremely important at this stage and sooner, because once the disease progresses beyond this point, it is sometimes difficult to prevent end-stage renal failure. If you take action now to lower your blood pressure and control your blood glucose level, it is possible to prevent diabetic nephropathy from progressing.
The single most important step you can take is to control your blood pressure. Early detection is essential. High blood pressure, or hypertension, is defined as anything greater than 130/85 mmHg. If your blood pressure is above this, it is likely to contribute to further damage to the kidney. If you show signs of hyperfiltration or microalbuminuria, your doctor may want to put on blood pressure-lowering medications even if your blood pressure is below this value. Your doctor may also recommend controlling the salt in your diet and trying to incorporate a regular exercise program into your daily activities to help control high blood pressure.
Keeping your blood glucose levels under control can also help slow the progression of kidney disease. During the Diabetic Control and Complications Trial, people with type 1 diabetes who maintained tight control decreased their risk of kidney disease by 35% to 56%. Even if you do not practice intensive therapy, keeping your blood glucose levels as close to normal as you can will help reduce the risk of damage to the kidneys.
Also talk to your doctor about other things that can harm your kidneys and contribute to kidney disease. In general, you want to avoid anything that could compromise the function of your kidneys. Many over-the-counter drugs can damage kidney tissue. These include ibruprofen (Advil, Motrin and others) and naproxen (Aleve). Other prescription anti-inflammatory drugs, antibiotics such as cisplatin, and some drugs used to treat psychiatric disorders, such as lithium, can also damage the kidneys.
If your kidneys are already damaged, the risk of further injury is even greater. Always talk to your doctor about any prescription or nonprescription medication before you take it. This includes any herbal or so-called natural remedies. You and your doctor should consider both the risks and benefits of any medication before you decide whether to take it.
If you need to have any X ray or radiographic imaging test done, make sure to talk to your doctor about the possible risks. Coronary angiograms, which evaluate the condition of your blood vessels, and intravenous pyelograms, used to examine the conditions of your kidneys, all use a radioactive tracer dye that is injected into your bloodstream. These dyes put you at risk for kidney failure a few days after injection, because they are filtered through your kidneys. Often the condition can be reversed, but it may require kidney dialysis.
However, there may be circumstances under which such a procedure is necessary—an emergency coronary artery bypass surgery, for example. If this is the case, your doctors will want to take precautions to minimize the risk. This can be done by giving you extra fluids before and after the procedure to dilute the dye, or by giving you certain drugs, such as theophylline plus allopurinol, that decrease the risk of acute kidney failure
If you have any history of neurogenic bladder, or any symptoms of urinary tract infections, incontinence, or an inability to fully empty the bladder, make sure to talk to your doctor right away. Even though it may be embarrassing to discuss some of these issues with your doctor, it is important, especially if there is evidence of kidney disease. When you are unable to fully empty your bladder, urine can back up into your kidneys and cause further damage. There are treatments for neurogenic bladder that can alleviate some of the problems associated with this condition.
As damage to the blood vessels that filter blood in the kidneys progresses, more and more protein from the blood leaks into the urine. In the early stages, the amount of leakage is small and microalbuminuria results. But in later stages, the amount of protein leaking through is substantial. At this point, more than 3.5 grams of albumin pass through to the urine each day. When this happens, you have nephrotic syndrome.
If you have nephrotic syndrome, you are losing measurable amounts of protein from the blood. One of the jobs of the blood protein albumin is to hold the water in the blood within the bloodstream. Without sufficient protein, water accumulates in the tissues of the body. In addition, the liver tries to synthesize more albumin to make up for the lost protein. In doing so, it also makes more cholesterol and fats, which create more health problems. At this point, you may begin to notice the symptoms of kidney disease.
Unfortunately, once you show signs of proteinuria—excessively high levels of protein in the urine—it is unlikely that you can prevent progression to end-stage renal disease, especially if you have type 1 diabetes. If you have type 2 diabetes, it is less likely that you will develop end-stage renal failure, but it is important to address the symptoms, because proteinuria is a predictor of stroke and cardiovascular disease. Approximately 80% of people with type 2 diabetes who develop nephrotic syndrome die within 10 years from cardiovascular complications and stroke. Therefore, it is extremely important to recognize and treat the problem as soon as possible.
If you have nephrotic syndrome, you may feel bloated and heavy and notice swelling in your feet and hands. Fluid may accumulate in your abdomen, chest and around your heart. You may carry up to 22kg in excess fluid retention. This can make you feel tired and short of breath. Your shoes and clothes may feel tight and it may be difficult to carry out even routine activities.
What You Should Do
If you feel any of the symptoms of nephrotic syndrome, talk to your doctor right away. There are steps you can take to delay the progression of kidney disease and to reduce the risk of complicating conditions such as cardiovascular disease and stroke.
It is also important not to dismiss your symptoms, because there may be other causes that may be contributing to your condition. For example, it is possible that a drug you are taking is contributing to your problem. Make sure your doctor is fully aware of any over-the-counter or prescription medications you are taking. Diabetic nephropathy almost always occurs in conjunction with retinopathy. If you have symptoms of nephropathy without any evidence of retinopathy, make sure you and your doctor consider other causes of kidney problems.
Once nephropathy has progressed to the point of nephrotic syndrome, with protein in the urine, it is less likely that you will be able to prevent progression of the disease. However, you can slow the progression and the worsening of symptoms by controlling your blood pressure and blood glucose levels.
The most important first step is to get your blood pressure under control. To do this, your doctor will most likely prescribe a blood pressure-lowering medication such as an ACE inhibitor. Other drugs that your doctor may prescribe include calcium channel blockers, diuretics and beta-blockers. Calcium channel blockers may decrease proteinuria and improve renal function and do not seem to impair glucose tolerance. However, you may notice an increase in water retention.
Some diuretics can worsen insulin resistance and make it harder for you to control your blood glucose level. They can also increase the likelihood of arrhythmias. Beta-blockers are effective at lowering blood pressure, but they can increase the risk of hypoglycemia. If your doctor does prescribe a beta-blocker, you should monitor your blood glucose levels closely. You and your doctor should discuss the pros and cons of any high blood pressure medication. Your doctor will try to recommend a drug that will provide maximum benefit to you with the lowest risk for introducing other problems.
If you are overweight, you should try to lose weight. If you are physically inactive, consider incorporating some sort of physical activity into your daily routine, even if it is just going for a walk each day or riding an exercise bicycle. Also, lower your salt intake, if necessary. You should not be taking in more than 4 to 5 grams of salt each day. Your doctor may suggest that you monitor your blood pressure at home on a daily basis.
Once you develop nephrotic syndrome, it is unlikely that you can halt the progression to end-stage renal failure, but you can slow the progression. The best way, of course, is to prevent progression to this stage. You can do this by lowering your blood pressure, keeping your blood glucose levels under control (practicing intensive therapy, if possible), exercising regularly, eating a balanced diet low in fat, avoiding alcohol and smoking, and seeing your doctor regularly.
Sources and References
The Diabetes Problem Solver—Quick Answers to Your Questions About Treatment and Self-Care by Nancy Touchette
Consequences of Glomerular Hyperfiltration: The Role of Physical Forces in the Pathogenesis of Chronic Kidney Disease in Diabetes and Obesity by Avry Chagnac, Boris Zingerman et al
The Tubular Hypothesis of Nephron Filtration and Diabetic Kidney Disease by Volker Vallon and Scott Thomson
Microalbuminuria by M Marre, B Bouhanick and G Berrut
Nephrotic Syndrome by Chia-Shi Wang and Larry Greenbaum