Hepatocellular injury, liver function tests

Diagnosing viral hepatitis may be difficult because most infected individuals are asymptomatic. Because symptoms cannot identify the specific type of hepatitis, laboratory serologies must be obtained (Table 21-2). In addition, liver function tests may be obtained to assess the extent of cholestatic and hepatocellular injury. However, the definitive test to determine the amount of damage and inflammation of hepatic cells is a liver biopsy. 

Response is dose related (as is hepatocellular injury), and both response and increased liver function tests (LFTs) resolve with stopping the drug. 

Reversible hepatocellular injury has been reported with naltrexone in doses of up to 300 mg/day, which is five times that usually used for opioid blockade (SED-11, 147) (17). Five of twenty-six patients treated with naltrexone for obesity developed raised serum transaminase activities after 3-8 weeks of treatment. In another study in which 60 obese subjects received naltrexone for 8 weeks, there were abnormal liver function tests in six patients. Three patients failed to complete the course. Nausea and vomiting occurred within the first 24 hours of treatment but responded to a reduction in dose. There were also changes in mentation such as decreased mental acuity, depression, and anxiety, all of which resolved after withdrawal. This is significant, as adverse effects from naltrexone have previously been attributed to mild physical withdrawal syndromes. 

Several cases of ticlopidine-induced hepatotoxicity have been reported (27). Between 10 days and 12 weeks after the start of treatment, patients develop jaundice, usually without fever, eosinophilia, or pain. Laboratory tests show a cholestatic or mixed cholestatic-hepatocellular pattern of injury. There is usually clinical and biochemical recovery within 1-11 months. Frank ticlopidine-associated liver injury is uncommon, but in one study, 44% of patients had abnormal liver function tests and about one-half of them had to stop taking the drug (22). 

There are no laboratory or radiographic tests of hepatic function despite the commonly ordered liver function tests. These commonly measured markers are substances produced by the liver and released into the bloodstream during hepatocellular injury, and are more correctly termed liver dysfunction tests. True liver function tests that assess the ability of the liver to eliminate substances that undergo hepatic metabolism, such as the " C-aminopyrine breath tesfi are limited by complexity and availability. 

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