Interview with Dr. Chi-Yuan Hsu: Understanding Acute Kidney Injury and Its Impact

Hear an audio interview with UCSF nephrologist Dr. Chi-Yuan Hsu discussing the risks associated with acute kidney injury.

Andrew Schorr:

Your kidneys are precious. We depend upon them many times during the day, and when they're not operating right we have a serious problem, which could even lead to dialysis, which you don't want to face if you can avoid it. And there's a problem that has not been discussed a lot: acute kidney injury. We'll hear all about it and what you need to be aware of next on Patient Power.

Hello and welcome to Patient Power sponsored by UCSF Medical Center. I'm Andrew Schorr.

Well, our kidneys are very precious organs, and you also think about your heart and your lungs and your brain, and we know that it's possible to have a heart attack, but in a way, did you know that you can have a kidney attack? Acute kidney injury, we have not discussed it enough, but we will on this program with two nephrologists, as a matter of fact, the chief of the division of nephrology, at UCSF Medical Center in San Francisco, and, also, a fellow in nephrology. They've been doing some groundbreaking research on acute kidney injury, something we need to be aware of, because quite frankly, when you pop those over the counter pills, and you do it willy nilly, you could be injuring your kidneys. Or, maybe, your kidneys have already been injured, and there are things that you and your doctor need to pay attention to.

Let's begin our program with Dr. Chi-Yuan Hsu. He is, as I said, the chief of the division of nephrology at UCSF in San Francisco. You have been involved in research on this, sir. Help us understand, what is acute kidney injury?

Dr. Chi Hsu:

Thank you for this opportunity to chat with you. We really appreciate it.

So, as we have been discussing, acute kidney injury is defined as the abrupt decline in kidney function. It's usually characterized by a drop in urine output, although that's not always the case, but it's definitely characterized by an increase in levels of serum creatinine and other waste products in the blood. Serum creatinine, as you may know, is a marker of kidney function. It is a waste product, made by the muscles, and its level in the blood is dependent, to great extent, by how well the kidneys function.

When the kidneys function well, the creatinine level is low. When it doesn't function well, the creatinine level is high, and in chronic kidney disease, the serum creatinine level goes — gradually over months to years to decades, eventually there is so much waste products that one needs chronic dialysis or transplant, which is end stage renal disease.

In acute kidney injury, however, the serum creatinine level increases within 48 hours due to some kind of acute insult. Acute kidney injury, stage I, is defined as a 50 percent abrupt increase in the serum creatinine over 48 hours. Stage II, acute kidney injury, is when the creatinine increases by over 200 percent. And stage III is when it increases by over 300 percent, or a threefold increase.

So, I think, that this is a condition which mostly happens to patients who are in the hospital. A number of factors predispose them, one of which is baseline chronic kidney disease, before you enter the hospital. But once you're in the hospital, a number of things can happen. For example, the reason that brought you into the hospital, such as a motor vehicle accident or crush injury, could lead to acute kidney injury, or you would undergo surgery, and after surgery one could have acute injury as well.

Many over the counter medications, such as Motrin, Aleve, or ibuprofen, predisposes one to acute kidney injury. So, you have chronic kidney disease, you should check with your doctors about which pills you are taking, just to be sure there's no added injury to baseline.

Recurrent Episodes of Acute Kidney Injury

Andrew Schorr:

Yeah, there you go. Also joining us is Dr. Raymond Hsu, who is a fellow in nephrology at UCSF, and he has been very involved in the research about acute kidney injury. So, Dr. Hsu, help us understand then, if someone is faced with this acute kidney injury, it's something that they and their doctors certainly need to be aware of, but maybe not just then, but maybe later in life as well. Am I right?

Dr. Raymond Hsu:

Yes, you are. I think, certainly, when the acute kidney injury is happening, both the patient and the doctor, who is taking care of the patient, should be aware of the conditioning, and treat the condition as needed. Specifically in most severe cases of acute kidney injury, temporary dialysis may be required, as Dr. Hsu said.

Later in life, we know from emerging literature, now, that patients who have suffered one episode of acute kidney injury are at risk of experiencing accelerated decline of their kidney function over time, as well as recurrent episodes of acute kidney injury. Therefore, it's important for patients to be aware that they've suffered this condition, even if they've recovered their kidney function completely, and to make it known that they suffered this condition, to their future providers.

In addition, as Dr. Hsu said, patients and providers should work together to minimize the number of potential insults to the kidneys in the future, such as exposure to potentially toxic medication, such as ibuprofen and Motrin, as well as making sound decisions on what type of procedures, and invasive surgery, a patient may undergo in the future, as each one of those things could lead to further episodes of acute kidney injury, as well.

Paying Attention to Over the Counter Medications

Andrew Schorr:

Dr. Raymond Hsu, let me ask you this: You mentioned, both of you have mentioned, over the counter medicines, and, let's face it, a lot of us just pop those pills like candy, but, from what you're saying, especially if we're taking too high a dose, I imagine, or maybe our own particular biology, that we maybe need to pay more attention. I know it's in the fine print on the bottles, but I don't know if many of us pay attention to it. Raymond, just help us understand, why do we have to pay more attention? How can they damage our kidneys?

Dr. Raymond Hsu:

Well, it depends on which over the counter medications we're talking about. In the case that we mentioned, I think one of the most commonly used medication classes is a class of over the counter pain medications called nonsteroidal anti-inflammatory, and we know from animal studies, as well as human studies, that those medications can cause a transient decrease in the amount of blood supply going to the kidneys, therefore, causing some degree of acute kidney injury.

Now, having said that, for the majority of the population, who have normal kidney function and have had no prior problems with their kidneys, taking these over the counter pain medications, at doses recommended on the bottle, is most likely quite safe. Where we run into trouble is for people who have had underlying kidney disease, and, at baseline, already have a decline in kidney function. So, for those people, taking such a medication may put them at risk for a real episode of acute kidney injury. So, it really depends on the individual patient, and how high risk they are for developing acute kidney injury.

Chronic Kidney Disease

Andrew Schorr:

Wow. So, Dr. Chi Hsu, so, I think, people are aware if somebody says, you know, I have a heart condition, but in a way, somebody may need to be aware, not on dialysis, but be aware, that they may have a kidney condition, and that they've had one of these acute injuries in the past, and that's something that they need to disclose to a doctor if they go to the emergency room. It's something that needs to be discussed, right?

Dr. Chi Hsu:

Yeah. So, I would echo the initial questions that you had asked us, that part of the emphasis on acute kidney injury dovetails, really well, with the emphasis in the drive to increase public awareness of chronic kidney disease, because chronic kidney disease is one of the major predisposing risk factors for acute kidney injury. And as Raymond pointed out, if you're completely healthy and well, and you play tennis, and you have a sore, you know, elbow, taking a Motrin is perfectly safe. It's among people who have chronic kidney disease in whom it is predisposed to acute renal failure.

And in particular, for example, many people, chronic disease are on diuretics, many of them are on a class of drug called angiotensin converting enzyme inhibitors, so ACE inhibitors, or angiotensin receptor blockers. The combination of being on a diuretic, an ACE inhibitor and a non-steroidal anti-inflammatory drug, certainly raises the risk of acute kidney injury higher. But, drugs like diuretic and ACE inhibitors and ARBs are really good to protect your kidneys in the long run; so, one should just be careful and run one's medication by one's physician, to just check that everything is fine.

In addition, there are certain herbal medications that are well described to cause either allergic, acute nephritis or have other reasons to predispose to acute kidney injury. So, the unknown herbal medications of unclear providence whose quality control is not strong, one should avoid if one has kidney disease.

Protecting our Kidneys

Andrew Schorr:

As I'm listening to this, I am thinking, you know, I don't think enough about protecting my kidneys. I guess, my mom said drink plenty of water, but, as you describe this, and then if somebody has had acute injury, acute kidney injury, which I understand is on the rise, then these are all things that we need to be aware of. We need to protect our kidneys and then be mindful if we have had an injury in the past, and, as you were saying, this all — as many of us as we get older, maybe take multiple medicines, all of this goes through our kidneys and we have to have a plan, with our doctor, of what is a safe way.

So, Dr. Chi Hsu, help me understand then, are there things that we also should be mindful? You mentioned risk factor for acute kidney injury is chronic kidney disease, many people don't even know they have it, our diet, our blood pressure. What are things that we need to be mindful of, there?

Dr. Chi Hsu:

So, that's a very good question. I think, the literature for chronic kidney disease shows that people should have their blood pressure checked. You should have your blood pressure checked regardless of whether or not you have kidney disease or not. People should maintain appropriate weight. People should just be sure they don't have diabetes, and maintaining a normal weight is an important part of that.

I have to point out, that drinking a lot of water, there's essentially very little evidence that protects your kidneys, so to speak. There are some very specific examples where it will reduce the risk of kidney stones, but for kidney disease, per se, there's actually very little evidence that drinking a lot of water would necessarily help. I think it's more important that people get their blood pressure checked, maintain a normal weight, and avoid having diabetes and things like that.

The three major risk factors for chronic kidney disease are high blood pressure, diabetes, and older age. Now, older age, one cannot avoid, but high blood pressure can be screened for, quite effectively. And maintaining a healthy weight will go a long way towards reducing the risk for diabetes.

And for acute kidney injury, I think a lot of that actually is in the healthcare system, because sometimes people acquire acute kidney failure in the hospital, and a lot of that has to do with the medical interventions we give. Sometimes it's unavoidable. If you have a bad car accident, you have crush injury, you need surgery. Then after surgery, if acute kidney injury is a by product, then it may not be changeable, but some of it I think is avoidable. And I think there's a lot of literature and research going on to figure out which components of it are.

There's a recent study, which is a very clever study in the ICU, where, when a patient's urine output starts dropping, the doctor gets a little pager, and then the doctor can go and manipulate the fluids and the drugs, and this has been shown to actually reduce the risk of acute kidney injury. Another study has shown that if a nephrologist is involved early in the course of acute kidney injury, when the creatinine starts to go up, then things can be done to ameliorate further increases in creatinine. So, there's a lot of interesting things which, I think, can be done from a physician point of view to reduce risk of acute kidney injury.

Normal Kidney Function Creatinine Levels

Andrew Schorr:

Doctor, so, you mentioned this creatinine several times. Is there a number that, we as patients, if we see our blood test results, should be aware of? What's a good number for us?

Dr. Chi Hsu:

Well, the creatinine is tricky. As I mentioned earlier, the creatinine is a waste product made by the muscle, constantly, and the production of this is higher, for example, in men than in women, in younger people than in older people, because there's more muscle mass. So, creatinine has been transformed by a number of equations to the estimated GFR, and that's the equation that the National Kidney Foundation and the NIH has been pushing for people to know their number.

So, normal kidney function is around 120 GFR, stage III kidney disease is GFR 60 or below, and you need dialysis around a GFR of 10. Now, a GFR of 60, however, cause corresponds to different levels of creatinine for different people, so it's not a simple one to one conversion. In general, a creatinine around one is normal, but that again varies from person to person. For acute kidney injury, it's the abrupt change in creatinine that matters. So, again, a 50 percent increase in creatinine, over 48 hours, is considered stage I chronic kidney disease, as is an acute rise in creatinine of .3 is the current definition.

Andrew Schorr:

Well, I can tell you, if I'm in the hospital and saying that my wife or I find out my creatinine is changing fast, I'm going to say, let's get a nephrologist in here quickly, so that I can avoid serious, serious problems, for sure.

Dr. Chi Hsu:

Some of it is mild and transient, but some of it, I think, is more serious, and perhaps early involvement with a nephrologist would be helpful.

Andrew Schorr:

Gentlemen, thank you for helping raise awareness in research about acute kidney injury. I just was not familiar with it, but I think we need to pay attention to it, and our doctors, certainly, and when we're in the hospital, certainly need to pay attention to it, and chronic kidney disease, as well, you mentioned, Chi, the important points there, as far as prevention and limiting it, and so I'm going to be mindful.

But, when I think about all this I want to protect my kidneys, value them for sure, just as I do my heart and other vital organs. I want to thank you both for being with us. Thank you, Raymond Hsu, for your research that you're participating in at UCSF. And, Chi Hsu, chief of the division of nephrology at UCSF, thank you for being with us as well.

Dr. Raymond Hsu:

Thank you.

Dr. Chi Hsu:

Thank you.

Andrew Schorr:

All right. This is what we do on Patient Power, is connect you with leading experts, and here, paying attention to your kidneys and kidney health, hopefully, you can avoid these acute problems, but if it happens to you then you want to get the best care with nephrologists who are in the know.

I'm Andrew Schorr. Thank you for joining us. Remember, knowledge can be the best medicine of all.


Reviewed by health care specialists at UCSF Medical Center.

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.

Related Information

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