How do we diagnose diabetic nephropathy?

In today’s post our previous lesson from last week on the pathophysiology (the what goes wrong) of diabetic nephropathy will be helpful. To review – the process of waste products filtering out of the blood and being excreted via urine occurs in the kidneys. Due to the damage done to the kidneys by high blood glucose levels associated with diabetes, the structures do not filter as well. As the damage accumulates, an important protein called albumin is leaked in the urine.

Diabetic nephropathy is diagnosed by testing albumin levels in the urine. Screening for microalbuminaria should be performed yearly starting 5 years after diagnosis in type 1 diabetes and right away in patients with type 2 diabetes.

There are two stages of diabetic nephropathy, both of which refer to urinary albumin levels:

1.     Microalbuminaria – urinary albumin excretion (UAE) is between 20 micrograms and 199 micrograms per minute

2.     Macroalbuminaria – UAE is greater than 200 micrograms per minute

The first step in diagnosing diabetic nephropathy is to measure albumin in a urine sample that would be collected as the first urine after waking up or at a random time. The results are expressed as urinary albumin concentrations. Any test that returns with abnormal results must confirmed in the following 3-6 months with two out of three tests indicating albumin in the urine.

As the disease progresses, urinary albumin excretion will increase. In addition to testing for albumin, your healthcare provider may run labs looking at creatinine. Creatinine levels are an accurate measure of kidney function.

Gross, J.L., Azevedo, Silveiro, Canani, Caramori, Zelmanovitz. (January 2005). Diabetic Nephropathy: Diagnosis, Prevention, and Treatment. Diabetes Care, 28 (1) doi:10.2337/diacare.28.1.164

What goes wrong in the body?

In our first blog post, we touched a little bit on what causes diabetic nephropathy, but today we’ll go into more detail and answer the question: “What goes wrong in the body that causes diabetic nephropathy? You know, as they say, prevention is the best medicine. So, if we know what causes it, hopefully we can better prevent it.

Remember diabetic nephropathy is a complication of diabetes that causes kidney damage or kidney disease. Diabetes significantly impacts the function of our kidneys (a very important organs in the body)! As previously discussed, the kidney contains million of small blood vessels that filter waste from the blood. The blood flows through vessels in the kidney and small molecules in the blood (some are waste products) squeeze through the holes acting a filter. These waste products then become part of the urine.

High sugar levels in the blood related to diabetes damages the structures that filter waste from the blood. These structures thicken and scar which decreases their ability to filter waste and remove fluid from the body. Due to the damange, waste products that would normally be eliminated via urine begin to build up in the blood. As the damage accumulates, an important protein called albumin is leaked in the urine.

So back to our original question: What goes wrong in the body that causes diabetic nephropathy? The answer is that when our blood sugar levels are too high for too long, the kidney gets damaged and loses its ability to filter our blood efficiently. So prevention is the best medicine, now what? The most important thing a person with diabetes can do is keep his blood sugar in his target range.

If you’re interested in learning more, please check out this link for a great explanation. 

Gross, J.L., Azevedo, Silveiro, Canani, Caramori, Zelmanovitz. (January 2005). Diabetic Nephropathy: Diagnosis, Prevention, and Treatment. Diabetes Care, 28 (1) doi:10.2337/diacare.28.1.164

Just how common is diabetic nephropathy?

Diabetic nephropathy is a common complication of diabetes that affects somewhere between 20 and 40 percent of persons with diabetes. This complication is associated with renal disease, an increased risk of cardiovascular (heart) disease and premature death.

As previously mentioned, about 10 percent of adults in the US have diabetes, but it is not equally distributed between age groups. Looking at persons age 65 and older, we see that 27 percent of this population group has diabetes. Among the adult population with diagnosed diabetes, 34.5 percent are affected by diabetic nephropathy.  In addition to persons older than 65, prevalence of diabetic nephropathy varied among ethnic groups in the US; the rates are higher for Hispanics, Asian and African-Americans when compared to whites.

Really quick – here are two words we need to define before moving on.

Morbidity – Having a disease

Mortality – The number of deaths in a population

The leading cause of end stage renal disease is diabetic nephropathy. End stage renal disease is another way of saying permanent damage to the kidney that ultimately leads to loss of function. When function is lost, the kidneys cannot do their main job – filtering the blood and removing waste products. In addition to accounting for a significant number of end stage renal failure cases, diabetic nephropathy is associated with a high mortality rate from cardiovascular disease.

In summary, diabetic nephropathy is a common complication of diabetes that continues to increase in the US population. It is strongly associated with end stage renal disease.  Cardiovascular disease (heart disease) associated with diabetic nephropathy is associated with a high rate of morbidity and mortality.  And ultimately, the United States spends millions of dollars each year to treat diabetes and its associated complications.

Chen, Jing. (2014) Diabetic Nephropathy: Scope of the Problem. Diabetes and Kidney Disease, 9-14. DOI 10.1007/978-1-4939

The Basics of Diabetic Nephropathy

Today I hope to give you a better understanding of what diabetic nephropathy is and why it is important and all of this in language you can understand!

Let’s start with some basic information about diabetes. Essentially, someone with diabetes does not have the ability to produce any or enough insulin, which causes elevated glucose (sugar) levels in the blood. There are two types of diabetes, 1 and 2, but type 2 is far more common. According to the American Diabetes Association, the most recent data tells us that 9.3 percent, or 29.1 million adult Americans, has diabetes and somewhere between 20 and 40 percent of these individuals will get diabetic nephropathy at some point in their life.

Diabetic nephropathy is a complication of diabetes that causes kidney damage or kidney disease. Nephropathy means the same thing as kidney disease.

You might be wondering – what do diabetes and glucose have to do with the kidney? The kidney contains million of small blood vessels that filter waste from the blood. The waste is excreted from the body as urine. Diabetes can damage the structures that filter waste from the blood. These structures thicken and scar which decreases their ability to filter waste and remove fluid from the body. A protein called albumin is leaked in the urine. The exact cause of diabetic nephropathy is unknown, but high blood sugar levels and high blood pressure are said to be important contributors.

There are a few factors that increase the risk of getting diabetic nephropathy:

1.    Being African-American, Hispanic or American Indian

2.    Developing type 1 diabetes before the age of 20

3.   Smoking

Stay tuned for next week when I talk in more detail about the causes and implications of diabetic nephropathy. 

Sources:
1. “Statistics about Diabetes.” American Diabetes Association, June 2014. http://www.diabetes.org/diabetes-basics/statistics/
2. Kivi, Rose. "Diabetic Nephropathy." Healthline, August 2014. http://www.healthline.com/health/type-2-diabetes/nephropathy#Overview1