Back in the early 2000s I faced some kidney problems, so, in my usual determined way, I set out to learn more about the kidneys and what I could do to protect them. I wrote about that experience in "Here's Lookin' at You, Kidneys" in the Fall/Winter 2005 issue of this magazine. During the past six years, much has changed for me and in our understanding of HIV and the kidneys, so it's time for an update.
The face of kidney disease in people with HIV is changing. Thanks to antiretroviral therapy (ART), we are surviving longer but we are also experiencing higher-than-normal rates of high blood pressure, diabetes and high cholesterol, which can all contribute to the development of kidney disease. People with HIV also have other risk factors that make us more susceptible: HIV can infect kidney cells and cause disease. Also, some medications taken by people with HIV (including certain antiretrovirals) can harm the kidneys.
Given all these factors, perhaps it shouldn't be surprising that about one-third of people with HIV in Canada have some kidney impairment. Because kidney function declines with age, this number will likely increase as more of us live longer. The good news is that we can do something about certain risk factors. But before we look at those risk factors and what we can do about them, let's take a moment to talk about the kidneys and what can go wrong with them.
Many people know that the kidneys -- two bean-shaped organs located on either side of your spine about midway up your back -- filter the blood and expel waste from our bodies, in the form of urine. But they do a lot more than that. The kidneys have four main functions:
- They remove extra fluid from the blood.
- They balance minerals in the blood.
- They remove waste products.
- They produce essential hormones that help us make red blood cells, regulate blood pressure and maintain calcium for our bones.
With kidney disease, it is usually the kidneys' filtering units -- the nephrons, which eliminate waste and excess fluid -- that are damaged. When this happens, dangerous levels of fluid and waste can accumulate over time in the body. Swollen hands and feet, fatigue, urinating more or less often than usual and cloudy or dark-coloured urine are some of the signals of possible problems, although there are often no obvious signs at first.
Kidney disease can be either acute or chronic. People with HIV are at higher risk for both. If we've had one, then we're more prone to develop the other.
When a person's kidney function declines quickly, this is called acute kidney injury. It can result from poisoning, infection or injury. A recent US study showed that in most cases of acute inflammation of the nephrons in people with HIV, drugs were to blame -- most commonly, nonsteroidal anti-inflammatory drugs (such as ibuprofen) and the antibiotic combo Septra/Bactrim. In only three out of the 21 cases of acute kidney injury due to medications, antiretrovirals were the culprit.
Chronic kidney disease involves a more gradual loss of kidney function and is defined as kidney damage that lasts for three months or more. The two most common causes of chronic kidney disease are diabetes and high blood pressure. Between two and 10 percent of people with HIV have chronic kidney disease.
When left untreated, kidney disease can be serious, even fatal, due to imbalances in blood levels of minerals and hormones or the build-up of fluid in the body. In extreme cases, dialysis or organ transplant is needed to replace the function that the kidneys normally perform. (People with HIV can now get kidney transplants in British Columbia, Ontario and Quebec.) Both acute and chronic kidney disease are associated with greater risk for cardiovascular disease and death among people with HIV than among HIV-negative people. Chronic kidney disease has also been linked to bone disease and cognitive impairment.
Who runs a higher risk of chronic kidney disease? People with HIV who can check off one or more of the following are at greater risk:
A low CD4 count or high viral load
People with HIV whose CD4 count is lower than 200 or whose viral load is greater than 4,000 are at increased risk.
Kidney failure due to HIV infection in the kidney cells (HIV-associated nephropathy, or HIVAN) is more common in people of African descent because of a genetic predisposition (though it is not more common in people of Ethiopian descent).
Hepatitis can damage the kidneys as well as the liver.
Alcohol and drugs
Consuming large amounts of alcohol or street drugs, such as cocaine, heroin and amphetamines, can damage the kidneys.
High cholesterol, high blood pressure and diabetes
People on ART who have high cholesterol, high blood pressure or diabetes have a higher chance of seeing their kidney function decline.
Every year after the age of 30, the average person loses one percent of their kidney function. Since accelerated aging has been seen in people with HIV, we may be even more susceptible to chronic kidney disease as we age.
People with HIV, even those with an undetectable viral load, have higher markers of inflammation in their blood than HIV-negative people. Inflammation is associated with a greater risk of both cardiovascular and kidney disease. Aging and excess body fat can also cause chronic low-level inflammation.
The antiretrovirals tenofovir (Viread, also in Truvada, Atripla and Complera), atazanavir (Reyataz) and indinavir (Crixivan) can cause kidney damage. Tenofovir can have acute and chronic effects on the kidneys. Fortunately, less than one percent of people who take tenofovir experience serious kidney injury. Atazanavir can cause kidney stones and interstitial nephritis, a condition in which the spaces between the nephrons swell. One study found that atazanavir was associated with a 22 percent increase in the incidence of chronic kidney disease per year of exposure; when taken with tenofovir, that rose to 41 percent. Indinavir, not used as much anymore, can cause crystals, kidney stones and interstitial nephritis to develop.
Medications that are increasingly being used not only after a transplant but also to treat inflammation can be a risk factor as well.
Because most people have no symptoms in the early stages of chronic kidney disease, regular testing is critical. Your doctor may order one or more of the following simple tests:
- a urine test to look for protein in the urine, which can be a sign of kidney damage. Levels of protein, or albumin, that are higher than normal for three months or more indicate chronic kidney disease.
- a blood test to measure creatinine, a waste product from the muscles that shows up in the blood when the kidneys aren't able to get rid of it. The result from this test is used to estimate your GFR (glomerular filtration rate), which tells you and your doctor how well your kidneys are doing their job (see Getting to Know GFR, below).
Fortunately, these tests are usually part of the standard set that your doctor orders during checkups and physical exams.
Unfortunately, in many cases, kidney disease cannot be completely reversed but its progress can often be slowed and the symptoms managed. Starting new meds, adjusting the dosage of drugs you're already taking and making lifestyle changes can all help. (Read My Kidney Story to see how I did it.)
For people with HIV infection in the kidneys (sometimes called HIV-associated nephropathy, or HIVAN), we now know that it's important to start ART regardless of CD4 count or viral load. We also know that it's important to stay on treatment: In a large international study, people who interrupted their ART had a 50 percent higher risk of developing chronic kidney disease than people who continued taking the medications. Other meds, such as corticosteroids (which reduce inflammation) and angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), which lower blood pressure, can also help protect kidneys damaged by certain types of kidney disease.
At the same time, as Jeff Kapler, pharmacist at the Southern Alberta Clinic for HIV/AIDS in Calgary, points out, many medications -- including ibuprofen, Aspirin and other over-the-counter drugs -- can damage the kidneys and should be used with caution.
Sometimes changes to the dosage of medications are needed to protect the kidneys. If you have signs of chronic disease (your GFR is lower than 60), your doctor will likely lower the dosages of certain meds, such as Septra/Bactrim, Atripla, atazanavir, maraviroc (Celsentri), lopinavir/ritonavir (Kaletra), and nucleoside drugs with the exception of abacavir (Ziagen).
However, medications are just one part of caring for your kidneys -- a holistic approach is crucial. That involves looking at how other parts of your life can impact your kidney health. For people with chronic kidney disease, an exercise program that combines cardiovascular exercise and resistance training has a long list of benefits: It can reduce inflammation and improve cardiovascular function, strength, endurance and quality of life. Not to mention that it can help prevent type 2 diabetes, reduce high blood pressure and improve your cholesterol. Be sure to talk to your doctor before you start an exercise program.
What we eat affects our kidney health, too. The DASH (Dietary Approaches to Stop Hypertension) diet -- which is low in salt and high in fruits, vegetables, legumes and nuts, whole grains and low-fat dairy products -- has been shown to lower blood pressure without medication. A recent study found that a DASH-style diet is much better than the Western diet (which usually includes more red meat, sweets, salt and saturated fats) for kidney function. A dietician -- ideally one who specializes in diets for people with kidney problems -- can provide more advice.
Many people with HIV take vitamins or supplements. These can have benefits, but be aware that some herbs can affect kidney function or interact with prescription medicines, including anti-HIV drugs, and over-the-counter products. Interactions can change the medication's effectiveness or make side effects of the drugs worse. Be sure to let your doctor know about all the herbs, supplements and other complementary therapies you are taking, especially if you have more significant kidney impairment, or if your GFR is below 30.
Being kind to your kidneys means balancing the right mix of meds, a kidney-friendly diet and an active life. Pharmacist Jeff Kapler puts it well: "The different parts of our bodies are so interconnected, and the kidneys are kind of at the centre of things. The management of your overall health is critical."
|My Kidney Story|
When I started taking tenofovir, my kidney function (as measured by my GFR, or glomerular filtration rate) remained stable. However, over the next couple of years, my creatinine shot up and correspondingly my GFR declined from 90 (normal) to below 60, indicating chronic kidney disease. I felt fine but I got a call from my doctor who told me that there was protein in my urine, which meant kidney damage. My only risk factor was tenofovir. (I know now that having elevated cholesterol from taking anti-HIV meds was probably contributing. Also, I was on dual protease inhibitors, which may have boosted my blood levels of tenofovir and increased its toxicity.)
Worried, I met with a nephrologist and my HIV specialist, who recommended that I stop taking Septra/ Bactrim (which I was on to prevent PCP), because it can be nephrotoxic, and switch from tenofovir to raltegravir (Isentress). I hated changing drugs because I have a history of side effects and allergic reactions, but the tenofovir had to go. Within a month, my GFR had risen to 65 -- a more reassuring number -- and it continued to rise, although it has never returned to normal.
In addition to switching meds, I also began to follow the Pritikin program of diet and exercise, which is known to reduce inflammation. Similar to the DASH diet, the program recommends eating fruits, vegetables, legumes, whole grains, seafood and lean chicken, and avoiding added fats, salt and sugar. It also stresses the benefits of exercise on a daily basis. These lifestyle changes lowered my blood pressure and cholesterol and made me feel 15 years younger! I continue to try to follow this program as much as possible to avoid disease (including kidney disease), prevent accelerated aging associated with HIV and have more energy.
Getting to Know GFR
The GFR (glomerular filtration rate) estimates how much fluid is passing through the nephrons and measures your kidney health.
|A GFR (ml/min) of||indicates ...|
|90+||normal kidney function|
|60-89||early kidney disease|
|<60||chronic kidney disease|
|<15||severely impaired kidney function -- this indicates that dialysis or a kidney transplant is needed|
Maggie Atkinson is an AIDS activist and lawyer. She is the former co-chair of AIDS ACTION NOW!, the founding chair of Voices of Positive Women in Toronto, and a recipient of the Order of Ontario. She has been living with HIV for more than 25 years.