Kidney Disease

As people live longer experts have found a link between kidney disease and HIV. Kidney disease is arguably the most life altering disease one can contract. The kidney is one of the most important organs in the human body. These bean-shaped organs, each the size of your fist, are located at about the middle of your back, just below the ribcage. The primary function of the kidneys is to filter waste and extra water from your blood. In fact, the kidneys process about 200 quarts of blood each day, filtering out about 2 quarts of excess water and waste products each day. This waste is eliminated from the body as urine.

Who Gets Kidney Disease?

Normal kidney (renal) function is essential for life. Unfortunately, kidneys don't always function properly. People with certain diseases are at greater risk for kidney disease than others. Some examples of diseases associated with renal dysfunction include:

• diabetes
• high blood pressure
• HIV/AIDS
• hepatitis b or c
• recurrent kidney stones
• polycystic kidney disease
• lupus

Other groups at risk:

• people who overuse pain killers, such as acetaminophen or ibuprofen
• users of cocaine or heroin
• people with a family history of kidney disease
• older adults

In fact, about 30 percent of HIV positive people will have protein in their urine, a substance not found in the urine of normally functioning kidneys. About 10% of those people will develop kidney disease. This translates to about 2% of all end stage renal disease patients being HIV positive.

Why is Kidney Disease an Issue in HIV?

There are many causes and types of kidney disease in the HIV population. For some, it is the virus itself doing damage to the kidney (the most common cause of renal disease in HIV positive patients). For others, HIV medications can cause conditions damaging to the kidneys. These include:

• Acute Tubular Necrosis (ATN) - Each kidney has small tubules that transport urine to the ureters through which the urine travels to the bladder where it is excreted. The tubules are responsible for reabsorbing certain substances, making urine mostly waste products and water. However, if these tubules are damaged, they can't do their job properly, meaning the kidneys don't do their job. ATN is a condition where these tubules are damaged due to a lack of oxygen or are damaged by exposure to certain chemicals, including some HIV medications. One such HIV medication is Viread (tenofovir), typically not considered toxic to the kidneys, it has been associated with ATN.

• Fanconi Syndrome - This syndrome is a result of damage to the tubules that then results in a failure of the kidney to reabsorb certain electrolytes and substances such as glucose. The HIV drug Viread (tenofovir) is associated with occasional cases of Fanconi syndrome.

• Lactic Acidosis - HIV medications can cause damage to the cells. This can lead to lactic acid building up in the blood, which is damaging to the kidneys.

• Obstruction - There are certain HIV medications that are known to increase the incidence of kidney stones. These kidney stones cause blockages in the kidney which damage kidney tissue and cause decreased kidney function. The HIV drug Crixivan, which is used much less often than it used to be was long known to cause kidney stones. The newer drug Reyataz also has an association with kidney stones in some patients.

Signs and Symptoms of Renal Disease

Unfortunately, most physical signs or symptoms of renal disease only occur after significant kidney damage has been done. Symptoms such as swelling in the hands, face, and legs can occur in severe conditions. Changes in urination -- such as decreased urination or changes in the color or concentration of the urine -- can also occur. Most of the signs of kidney disease show up in blood and urine tests.

• Blood Urea Nitrogen (BUN) - Nitrogen is a waste product typically removed from the blood via the kidneys. When the kidneys malfunction, the amount of nitrogen waste in the blood increases as does the BUN value.

• Creatinine - Creatinine is produced when muscle is broken down. It is then filtered from the blood by the kidneys. When there is kidney damage, creatinine builds up in the blood. An elevated creatinine level in the blood is a signal that the kidneys are not working as they should.

• Protein - Finding higher than normal levels of protein in the urine is a signal that there is an issue with reabsorbtion or that damage has been done to the kidney.

While blood and urine tests can signal your doctor that there may be a problem with your kidneys, a biopsy of kidney tissue is the most accurate means of diagnosing kidney disease.

It's becoming clear that people with HIV do have an added risk of kidney disease. HIV medications or the virus itself can do significant damage to your kidneys; so much that people can have total renal failure requiring dialysis and transplant. Talk to your doctor about the health of your kidneys and if the medications you are taking put you at added risk for kidney disease.

_Sources

Choi, A. and Rodriquez, R.; "Renal Manifestations of HIV"; HIV Insite Knowledge Base Chapter; Nov. 2003; Updated Jan. 2008.

Krummel, T.; "Tenofovir-induced acute renal failure in an HIV patient with normal renal function."; Nepfrol Dial Transport (2005) 20:474.

Swierzewski, S.; "Acute Tubular Necrosis (ATN): An Overview, Causes, Symptoms, Diagnosis, Treatment"; Nephrology Channel; 01 May 2001.