HIV and Liver Function Tests (LFTs)

Diagnostic Tests Used to Measure the Health of Your Liver

Blood Test used under Creative Commons license https://www.flickr.com/photos/lori_greig/4185759295
Photograph © Lori Greig

Liver function tests (LFTs) are a battery of routine blood tests that gives your doctor an idea of how well your liver is working. From these investigations, your doctor can identify underlying liver dysfunction, medication stresses affecting the liver, or diseases of the liver such as hepatitis B (HBV) or hepatitis C (HCV). There are a number of different tests that comprise LFT monitoring, including:

Albumin (ALB)

Albumin is a protein produced by the liver that helps maintain osmotic pressure in the vascular space. By maintaining this pressure, fluid stays in the vascular system instead of leaking out into the tissues resulting in swelling (edema). Albumin also carries certain minerals in the blood stream.

  • Normal values: 4 - 6
  • Elevated: Usually indicates dehydration
  • Below normal: Can indicate liver dysfunction or insufficient protein intake.

Alkaline phosphatase (ALK PHOS)

Alkaline phosphatase is an enzyme found in many organs in the body, including the liver.

  • Normal values: 30 - 120.
  • Elevated: A warning sign that there is some type of liver dysfunction resulting in liver tissue damage.
  • Below normal: Usually not significant.

Alanine aminotransferase (ALT or SGPT)

This protein is found primarily in the liver. It is released into the blood when there has been some sort of liver tissue damage.

  • Normal values: less than 35.

  • Elevated: Indicates that liver tissue damage has occurred as a result of infection, medications,obstruction, cirrhosis or injury to the liver.

  • Below normal: There is no known disease process that results in a low ALT level.

Aspartate aminotransferase (AST or SGOT)

This protein is found primarily in the liver.

It is released into the blood when there has been some sort of liver tissue damage.

  • Normal values: less than 35.

  • Elevated: Indicates tissue damage as a result of such things as obstruction, hepatitis, or cirrhosis.

  • Below normal: Usually not significant

Total bilirubin (TBIL)

Bilirubin is a normal component of red blood cells. When these cells break down free bilirubin is released into the blood. Bilirubin is then carried to the liver where it is broken down and excreted. When the liver is not functioning properly, bilirubin builds up in the body, causing jaundice (yellowing of the skin and eyes and darkening of the urine).

  • Normal values: less than 1.0
  • Elevated: usually caused by a dysfunction of the system that breaks down bilirubin which includes the liver. Such an elevation can be caused by an obstruction or liver failure.

Reasons for Elevated Liver Enzymes

When treating an HIV infection, liver enzymes can be elevated for a number of reasons, including drugs used to treat HIV, coinfections commonly associated with HIV, and, in some cases, HIV itself.

These can Include:

  • Viral hepatitis - According to the Centers for Disease Control and Prevention (CDC), hepatitis coinfection is frequently seen in people with HIV, with nearly 30% coinfected with hepatitis C (HCV) alone. The disease can severely affect the liver, causing scarring (fibrosis) and chronic degeneration (cirrhosis).
     
  • Antiretroviral drugs - Certain antiretroviral drugs (ARVs) can cause hepatoxicity (toxicity of the liver) in a proportion of people expose to those drugs. Chief among them are nucleoside reverse transcriptase inhibitors (NRTIs), the non-nucleoside reverse transcriptase inhibitor Viramune (nevirapine), and the protease inhibitors Aptivus (tipranavir) when boosted with Norvir (ritonavir). Regular LFT monitoring can better ensure the avoidance of treatment-related hepatoxicity.
     
  • Alcohol and other medications - Alcohol has long been associated with liver dysfunction, exacerbating associated liver infections as well as the drug associated with hepatotoxicity. Even dietary supplements like St. John's Wort (Hypericum perforicum) is known to increase the hepatotoxic potential of certain ARVs.
     
  • Non-alcoholic fatty liver disease (NAFLD) - Anywhere from between 17%-33% of Americans are diagnosed with non-alcoholic fatty liver disease (NAFLD), which is related to obesity and can cause inflammation and fibrosis of the liver.

Sources:

Price, J. and Theo, C. "Liver Disease in the HIV-Infected Individual." Clinical Gastrointestinal Hepatology. September 7, 2010; doi:  10.1016/j.cgh.2010.08.024.

Centers for Disease Control and Prevention (CDC). "HIV/AID and Viral Hepatitis." Atlanta, Georgia; accessed June 3, 2015.

Department of Health and Human Services (DHHS). "Side Effects of HIV Medicines - HIV and Hepatoxicity." AIDSInfo. Washington, D.C.; accessed June 3, 2015.

Edited by James Myhre and Dennis Sifris, M.D.

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