Liver Fibrosis in HIV-Infected Patients With Elevated Liver Enzymes on Antiretroviral Therapy

This study will provide a basis for research on the impact of liver injury caused by antiretroviral therapy in HIV-infected patients. Elevated liver enzymes called AST and ALT are common in HIV-infected patients taking antiretroviral medications and can indicate liver damage. Although there are a number of possible causes for these elevations, such as infections with a hepatitis virus, antiretroviral medications alone can lead to the elevations. The study will focus particularly on evidence of liver fibrosis, which is a sign of progressive liver damage. HIV-infected patients 18 and older who 1) have been taking combination antiretroviral therapy for at least 12 months and have been on a stable regimen for at least 3 months, and 2) have had elevated AST or ALT levels for at least 6 months may be eligible for this study. Patients who have had liver biopsies performed in the past may be eligible for participation. Participants undergo the following tests and procedures over a 12-month period: * Oral glucose tolerance test: The patient drinks a glucose (sugar) drink. Blood samples are then drawn over 2 hours through an intravenous (IV) line in the patient's arm. This test measures how high the patient's blood sugar and insulin levels rise after drinking a standard glucose load. * Transient elastography: This ultrasound test uses vibration (sound waves) to measure liver stiffness (fibrosis). Vibrations move faster through a fibrotic liver. * Triple-phase CT scan and single slice CT scan of L4-5: Patients fast for 4 hours before the CT scan. A contrast material is injected through a catheter placed in an arm vein to improve the visibility of the liver in the specialized X-ray images obtained in the CT scanner. * Liver biopsy: This test removes a small sample of liver tissue for microscopic examination, particularly for evidence of fibrosis. The skin over the biopsy site is numbed and a needle is passed through the skin and rapidly in and out of the liver. Patients may