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HIV & Kidney Disease: African-Americans with HIV are more susceptible to type of kidney disease known as HIVAN
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NY Daily News BY KATIE CHARLES
July 22nd 2009, 4:00 AM
THE SPECIALIST: DR. PAUL KLOTMAN ON HIV-RELATED NEPHROPATHY
As chairman of the Samuel F. Bronfman Department of Medicineat Mount Sinai, Klotman has been studying the kidney for almost 30 years. He is one of the world's leading experts on the kidney diseases associated with HIV.
WHO'S AT RISK
HIV-associated nephropathy (HIVAN) is a type of kidney disease that damages all of the organ's structures. "For the general population of AIDS patients, kidney failure is the fourth-leading contributor to death, and it takes many forms," says Klotman. "Nephropathy most often strikes people of African descent ... [it] causes scarring in the kidney's filtering mechanism and distorts the tubules that make up 90% of the kidney with microcysts."
Doctors estimate that between 2 million and 4 million people of African heritage have HIVAN, including between 4% and 12% of HIV-positive African-Americans. Previously, doctors noticed that HIV-positive patients with kidney disease on dialysis were more likely to have relatives who also had kidney disease requiring dialysis. Just this year, several papers came out identifying a gene that is strongly associated with the kidney diseases most prominent among blacks. "The gene makes you susceptible to kidney diseases, and then something else in the environment becomes a trigger - for instance, HIV," says Klotman. "This variant of the gene, called MYH9, is almost exclusively present in individuals of African descent." Along with HIV, other factors can trigger kidney disease, but doctors haven't identified them yet.
Nephropathy can occur in patients at any stage of HIV infection. Since the late '90s, when highly active retroviral therapy (HAART) was introduced, deaths from AIDS have dropped dramatically. As patients lived longer, they also had more time for other diseases to develop. "Now we have about 1,000 cases of HIVAN every year," says Klotman. "And we estimated that at least 10,000 patients will be HIV-positive and on dialysis by 2020."
SIGNS AND SYMPTOMS
HIVAN is almost always associated with chronic kidney failure, which develops stealthily. "Patients usually don't know they have kidney disease," says Klotman. "Most of the symptoms occur very late. You can be asymptomatic until you've lost 80%-85% of your kidney function." As a result, HIVAN is more often noticed in the course of routine blood work - and for this reason, the Infectious Disease Society of America recommends that all HIV-positive people be screened for kidney disease.
At a late stage in the disease, people start presenting signs like swelling of the legs and going to the bathroom a lot. "There are very few indications of problems until you've lost a lot of kidney function," says Klotman. "So the real signs are things we see in blood tests."
TRADITIONAL TREATMENT
The antiretroviral drugs used in HAART that are so effective at reducing deaths from AIDS are also the best option for staving off kidney disease. In the past, doctors would wait to start patients with HIV on antiretrovirals until their CD4 counts (measuring the immune system's strength) dropped below a certain threshold. The new recommendation from the Infectious Disease Society of America is that people with kidney disease should be treated with HAART, independent of their CD4 count.
"Now, people who show signs of kidney disease should start receiving HAART immediately," says Klotman. "The focus increasingly is on treating the nephropathy with antiretrovirals." Studies have shown that when patients go off antiretrovirals, their kidney function worsens immediately; it improves again if they go back on the drugs.
Thanks to advances in pharmaceutical research, antiretroviral drugs have improved greatly and become easier for the patient to take properly. "Now you can get down to one pill a day, orally," says Klotman. "In the past, you used to take many pills throughout the day." The latest generation of drugs also kicks in right away to keep the virus from replicating. "It reverses the effects of HIV pretty dramatically, improving appetite and body weight," says Klotman. "The patients immediately gain weight and do better."
The other options for HIVAN patients include dialysis and kidney-transplant surgery. "Now people can live a long time when their virus is well-controlled," says Klotman. "So they are candidates for kidney transplant, which can give them normal renal function." Amazingly, the failure rate for kidney transplants is no higher for HIV-positive patients than the general population.
Doctors are increasingly able to manage both HIV and its associated diseases like HIVAN. "HAART is so effective that people aren't getting as much kidney disease," says Klotman. "Right now doctors talk about the fact that HIV patients can probably live to the point where they don't die of HIV, but die of the traditional killers like heart disease and kidney disease."
RESEARCH BREAKTHROUGHS:
In recent years, doctors have made tremendous advances in their understanding of both HIV and its associated kidney disease. Through the use of animal and human studies, researchers were able to identify the gene that leads to susceptibility.
Studies involving mice demonstrated that HIV directly caused kidney disease; before that, doctors had wondered if the drugs being used to treat HIV might be causing HIVAN. "Through animal experiments, it became clear that HIV had to enter inside the kidney before nephropathy developed," says Klotman. "Along with T cells, HIV also infects kidney cells, distorting them and causing them to proliferate in an unhealthy way that messes up the structure and function of the kidney."
These findings have major implications for both the treatment of HIVAN and of HIV more generally. "In thinking about a cure, we know now that we have to clean out the brain and the kidney," says Klotman. "Those are things we have to know if we can ever achieve a cure for AIDS."
QUESTIONS FOR YOUR DOCTOR:
For any patient who is HIV-positive, a good question to ask is, "What is my kidney function?" Depending on your blood work and kidney function, ask your doctor,"Should I be started now on antiretrovirals?"
WHAT YOU CAN DO:
Take your medicine. Adherence is the biggest issue for HIV-positive patients; people can neglect to take their medicine because of the complexity of the drug regimen, side effects or cost.
Maintain a healthy blood pressure. "High blood pressure leads to more rapid deterioration of the kidney," says Klotman. "So keep your blood pressure under control."
Find a good specialist. Klotman advises patients to find a doctor who specializes in HIV care through the Infectious Disease Society of America (idsociety.org). If you also have kidney disease, see a nephrologist, too.
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