Kidney Problems

The kidneys are two bean-shaped organs found on either side of the spine at about the waist. Their job is to filter the blood and clear toxins, salts and water from the body. The water and waste products are turned into urine.

The kidneys also play an important role in controlling the blood pressure. They control the level of acid and other chemicals in the blood.

Disorders of the kidneys are called nephropathy. HIV-related kidney problems are called HIV-associated nephropathy or HIVAN. The most serious kidney problems can lead to kidney failure.

Symptoms

By the time there are signs of kidney problems, a large part of the kidney's ability to work has been lost. Signs of kidney problems include:

• Eliminating large amounts of urine
• Fatigue
• High blood pressure
• Loss of appetite
• Rapid heart rate
• Swelling of the face or legs
• Thirstiness

Causes

Some kidney problems are caused by HIV itself. A person with advanced HIV disease and low CD4 cell counts is more likely to have problems.

Some of the drugs used to treat HIV are known to be causes of kidney problems. Viread (tenofovir) is a nucleotide reverse transcriptase inhibitor that may cause problems. Crixivan (indinavir) can form crystals in the kidneys. This happens most often in people who don't drink enough water. It is less of a problem when indinavir is boosted with ritonavir. Kaletra (ritonavir-boosted lopinavir) may cause kidney stones.

Causes and Risk Factors

Kidney disease is more likely in people who have:

• A higher viral load (especially one above 4,000)
• A lower CD4 count (especially one below 200)
• Diabetes
• Hepatitis B or C
• High blood pressure

Being older or being African-American or Haitian also raise the chance of developing kidney problems.

Prevention

The best way to try to avoid kidney problems is to manage those risk factors that can be controlled. This means keeping blood pressure low, managing diabetes and drinking plenty of fluids. Any steps taken to improve the health generally will be helpful to the kidneys.

Diagnosis

Because people with HIV have a higher risk of kidney problems, they need to be checked regularly. Kidney function tests should be done when a person is first diagnosed with HIV. If there is a high risk of developing kidney problems, the tests should be repeated every year.

The best way to diagnose kidney problems is through a blood test. Blood tests are used to monitor a personÕs response to treatment. Because kidney problems often donÕt have symptoms until a lot of damage is done, having regular blood tests is important.

Some of the tests a doctor may order to monitor how the kidneys are working are:

• Urine test. This is the most common test used to see how well the kidneys are working. It checks for protein, sugar, ketones (produced when the body breaks down fat), blood and nitrites in the urine. Even small amounts of protein show up in the urine before the kidneys have suffered major damage from kidney disease.
• Blood urea nitrogen (BUN). This measures the nitrogen in the blood. The kidneys normally remove BUN. Having a high BUN level can be a result of a high-protein diet, not getting enough water or kidney or heart failure.
• Creatinine clearance. Creatinine is made when muscle is broken down. When creatinine levels go up in the blood, itÕs a sign of that the kidneys arenÕt working normally.
• An ultrasound. This uses sound waves to create an image of an organ inside the body.
• A kidney biopsy. In a biopsy, a small sample of tissue is taken from the kidney to look at under a microscope.

Treatment

How kidney disease is treated in a person with HIV will vary. Treatment depends on the nature of the kidney disease, how well the person is responding to HIV treatment and other factors.

If kidney disease is serious, it may be necessary to make changes in the anti-retroviral drugs being used. Stopping a drug such as tenofovir has to be balanced with the positive effects of anti-HIV treatment. Taking antiretrovirals can help improve a person's general health and prevent other infections. This helps keep the kidneys working.

It may be necessary to lower the doses taken of all nucleoside and nucleotide reverse transcriptase inhibitors, except Ziagen¨ (abacavir).

Making sure the person gets plenty of fluids and taking steps to lower the blood pressure are helpful.

In the case of severe kidney disease or kidney failure, dialysis may be needed. This is a process where the blood is filtered by a machine and then returned to the body. The machine takes over the job of the kidneys.

A kidney transplant may also be an option. In the past, this wasnÕt possible because of the immune system suppressing drugs that are used after a transplant to prevent organ rejection. With the antiretroviral therapy now being used the risks of these anti-rejection drugs has been reduced. Most transplant centers only accept people with a CD4 cell count over 200 and an undetectable viral load. Under these conditions, people with HIV have about the same outcomes as other people getting kidney transplants.