Chronic Kidney Disease #1: Tests for Early Detection

Doctor's Insight.

Chronic Kidney Disease, or CKD...

when this disease progresses, it causes kidneys to lose their function, making it impossible to live without dialysis or a kidney transplant.

The number of patients continues to grow worldwide.

The prevalence has increased by approximately 30% over a period of 27 years since 1990.

As of 2017, 1 out of every 11 people are affected.

Hello and welcome to Doctor's Insight.

This is a life-size model of a kidney.

We have one on each side of our body.

Chronic Kidney Disease or CKD can be diagnosed with blood and urine tests.

In Japan, for example, tests for CKD are a part of the regular health checkup.

Today, we'll focus on the different tests available for the early detection of Chronic Kidney Disease.

Today's expert is Dr. Masaomi Nangaku, President of the International Society of Nephrology.

He is a world-renowned nephrologist who has spent decades conducting research on the cause and the treatment of kidney disease.

Dr. Nangaku, thank you so much for joining us today.

Thank you for having me.

Chronic Kidney Disease or CKD has increased by about 30% worldwide since 1990.

Can you tell us why?

Well, what I can say is that CKD is largely associated with lifestyle diseases such as diabetes, high blood pressure, dyslipidemia and obesity.

Cases of lifestyle diseases that cause CKD are increasing worldwide, due to unhealthy diet, lack of exercise and other factors.

In developed countries, the aging population is also thought to be a major factor.

Now, let's find out what happens when CKD progresses.

When CKD progresses to "kidney failure," the kidney greatly loses its function, and various symptoms appear.

They include fatigue, severe anemia, swollen hands or feet, palpitation or shortness of breath, and weak bones.

If CKD progresses further to end-stage kidney disease, the kidneys completely lose their function and the patient must undergo dialysis which replaces kidney function

or have a kidney transplant in order to live.

As CKD progresses, patients become more prone to complications.

This means that the condition is more likely to cause life-threatening diseases such as heart attack and stroke.

Once CKD develops, the kidneys cannot be restored to their original state even with treatment.

That's why it's important to detect CKD as early as possible, while the damage is still mild, so you can take steps to preserve kidney function.

Yes, but I've heard that people often don't experience any noticeable symptoms.

So, that seems really complicated.

That's right.

That's why it's important to get tested regularly.

Once you turn 20, you should start thinking about getting tested through a blood test or a urine test.

I see.

Now, what exactly do they look for in your kidneys during kidney tests?

Let's find out.

One of the main functions of the kidneys is to remove waste products by making urine.

One test that measures how well your kidneys are working is a blood test.

Doctors look at the level of creatinine.

Creatinine is a type of waste product.

Looking at the creatinine level, the eGFR can be calculated.

eGFR is a number that indicates kidney function.

For instance, an eGFR of 60 indicates that the kidney is working 60% compared to a healthy kidney.

When it drops to less than 60%, you should get retested within 1 to 3 months.

If the level of your eGFR continues to be less than 60 for more than 3 months, you will be diagnosed with CKD.

In addition to blood tests, I understand we also need to take a urine test.

Is that right?

Yes, in the urinalysis, we look for the presence of proteinuria.

When the kidneys are functioning properly, protein is not found in urine.

However, when they begin losing their function, protein which the body normally needs, is more likely to be released into the urine.

Now, let's take a look at how a person develops proteinuria.

Our kidneys contain what is called glomerulus, which is a bundle of tiny blood vessels, or capillaries.

This is where blood is filtered and waste products from the blood are released into the urine.

When the kidneys are functioning normally, protein is not filtered out due to the barrier function of the blood vessel walls.

However, if a person has high blood pressure, blood vessels throughout the body are damaged, including the capillaries in the glomerulus.

This causes proteinuria, in which protein is filtered out due to the damaged barrier function in the blood vessel walls.

In addition, once CKD develops, people who do not have high blood pressure to begin with are more likely to develop hypertension.

As a result, proteinuria can easily occur.

Proteinuria is determined depending on the concentration of protein.

If the test result includes a plus, you will be diagnosed with "Suspected CKD."

Do we need to take both a blood test and a urine test?

Yes.

The severity of CKD is diagnosed based on the results of both eGFR and proteinuria.

For instance, if the eGFR is 90 or higher, but proteinuria is "1 plus," the patient is diagnosed with "moderate risk CKD."

If the eGFR is as low as 55, but there is no proteinuria, the patient will be diagnosed with having "low risk CKD."

I see.

That is really good point.

If they are not included in your checkup, or if health check itself is not readily available, please consult with your family doctor or visit a medical institution nearby to get tested regularly.

So by getting tested after turning 20, we can detect CKD at an early stage?

Generally, yes.

However, about half of diabetic patients develop diabetic kidney disease, which is CKD caused by diabetes.

There are cases in which diabetic kidney disease cannot be detected at an early stage with general methods.

This varies depending on the country, but in places like Japan where they test for proteinuria, it is important to check for albuminuria with a urine test.

So for people with diabetes, it's important to get a urine albumin test.

But before we get to that, let's find out why CKD caused by diabetes is hard to detect in its early stages using common testing methods to measure protein in urine.

For people with diabetes, proteinuria is also likely to occur.

Patients with proteinuria account for about 80% of all diabetic kidney disease patients.

However, this type of disease progresses quickly, and by the time proteinuria is detected, it may already be past the early stages.

Here, we should look for albuminuria.

Albumin appears in your urine at an earlier stage than protein, so it can lead to the early detection of CKD.

Albuminuria testing is recommended for diabetic patients who test negative for proteinuria.

So the first step is to check your kidney function by taking both a blood test and a urine test.

Exactly.

The best way to detect CKD at an early stage is to get tested regularly.

If your test result shows no abnormalities, it is reassuring to know that you don't have CKD at that point.

A good time to start getting tested is when you turn 20.

Dr. Nangaku, thank you so much for your time today.

Thank you.