Aminotransferases acute

HCV infection is rarefy diagnosed in the acute phase, as most acutely infected individuals are asymptomatic. Between 50% and 90% of patients develop chronic infection, however, and this warrants early therapy. After occupational exposure with a known date, treatment should not be started before the acute episode characterized by alanine aminotransferase elevation, but it should always be started within 24 weeks after the onset of symptoms. The optimal treatment schedule for acute hepatitis C is controversial. Pegylated IFN-a monotherapy at the standard dose for 24 weeks yielded SVR rates close to 100% in symptomatic patients referred to tertiary care centers (De Rosa et al. 2006 Jaeckel et al. 2001 Santantonio et al. 2005 Wiegand et al. 2006). Shorter therapy may be envisaged (Calleri et al. 2007). Combination with ribavirin is recommended if a first course of pegylated IFN-a monotherapy fails to eradicate the infection. Viral elimination appears to be independent of the HCV genotype and the HCV RNA level (Calleri et al. 2007 De Rosa et al. 2006 Jaeckel et al. 2001). 

The probable metabohc defect in type I tyrosine-mia (tyrosinosis) is at himarylacetoacetate hydrolase (reaction 4, Figure 30-12). Therapy employs a diet low in tyrosine and phenylalanine. Untreated acute and chronic tyrosinosis leads to death from liver failure. Alternate metabolites of tyrosine are also excreted in type II tyrosinemia (Richner-Hanhart syndrome), a defect in tyrosine aminotransferase (reaction 1, Figure 30-12), and in neonatal tyrosinemia, due to lowered y>-hydroxyphenylpyruvate hydroxylase activity (reaction 2, Figure 30-12). Therapy employs a diet low in protein. 

Heiman AS, Tonner LE. 1995. The acute effect of lead acetate on glucocorticoid regulation of tyrosine aminotransferase in hepatoma cells. Toxicology 100(l-3) 57-68. 

The aminotransferases, aspartate transaminase and alanine transaminase, are enzymes that have increased concentrations in plasma following hepatocellular injury. The highest concentrations are seen in acute viral infections, or ischemic or toxic liver injury. 

The diagnosis of acute HAV infection is based on clinical criteria of acute onset of fatigue, abdominal pain, loss of appetite, intermittent nausea and vomiting, jaundice or elevated serum aminotransferase levels, and serologic testing for immunoglobulin (Ig) G anti-HAV. 

Data from American Pain Society. Prinaples of Analgesic Use in the Treatment of Acute Pain and Chronic Cancer Pan, 5th ed. Glenview, IL American Pain Society, 2003 Anonymous. American Hospital Formulary Service. In Mc/oyGK, ed. Drug Information. Bethesda, MD American Society of Hospital Pharmacists, 1987, 1991, 1994, 1997, 1999,2001,2003,2004,2005,2006,2007 Anonymous. Facts and Comparisons. Philadelphia Lippincott, 1986, 1991, 1994, 1997,2000,2003,2004,2006,20Q7 and Watkins PB, Kaplowitz N, Slattery TJ, et al. Aminotransferase elevations in healthy adults receiving 4 grams of acetaminophen daily A randomized controlled trial. JAMA 2006 296 87-93. 

ALL acute lymphocytic leukemia ALS amyotrophic lateral sclerosis ALT alanine aminotransferase (a liver enzyme)... 

Hepatic Effects. Carbon tetrachloride has been known for many years to be a powerful hepatotoxic agent in humans and in animals. The principal clinical signs of liver injury in humans who inhale carbon tetrachloride are a swollen and tender liver, elevated levels of hepatic enzyme (aspartate aminotransferase) in the serum, elevated serum bilirubin levels and the appearance of jaundice, and decreased serum levels of proteins such as albumin and fibrinogen (Ashe and Sailer 1942 McGuire 1932 New et al. 1962 Norwood et al. 1950 Straus 1954). In cases of acute lethal exposures, autopsy generally reveals marked liver necrosis with pronounced steatosis (Jennings 1955 Markham 1967 Smetana 1939), and repeated or chronic exposures leads in some cases to fibrosis or cirrhosis (McDermott and Hardy 1963). 

Adverse effects that are not unequivocally related to inhibition of prostaglandin synthesis include hepatic effects (hepatitis, hepatic necrosis, cholestatic jaundice, increased serum aminotransferases), dermal effects (photosensitivities, Stevens-Johnson syndrome, toxic epidermal necrolysis, onycholysis), central nervous system (CNS) effects (headaches, dizziness, tinnitus, deafness, drowsiness, confusion, nervousness, increased sweating, aseptic meningitis), ocular effects (toxic amblyopia, retinal disturbances), and certain renal effects (acute interstitial nephritis, acute papillary necrosis). 

Naltrexone is generally taken once a day in an oral dose of 50 mg for treatment of alcoholism. An extended-release formulation administered as an IM injection once every 4 weeks is also effective. The drug can cause dose-dependent hepatotoxicity and should be used with caution in patients with evidence of mild abnormalities in serum aminotransferase activity. The combination of naltrexone plus disulfiram should be avoided, since both drugs are potential hepatotoxins. Administration of naltrexone to patients who are physically dependent on opioids precipitates an acute withdrawal syndrome, so patients must be opioid-free before initiating naltrexone therapy. Naltrexone also blocks the therapeutic effects of usual doses of opioids. 

The most common adverse effects of indinavir are indirect hyperbilirubinemia and nephrolithiasis due to crystallization of the drug. Nephrolithiasis can occur within days after initiating therapy, with an estimated incidence of approximately 10%. Consumption of at least 48 ounces of water daily is important to maintain adequate hydration. Thrombocytopenia, elevations of serum aminotransferase levels, nausea, diarrhea, insomnia, dry throat, dry skin, and indirect hyperbilirubinemia have also been reported. Insulin resistance may be more common with indinavir than with the other Pis, occurring in 3-5% of patients. There have also been rare cases of acute hemolytic anemia. 

Acute inorganic lead poisoning is uncommon today. It usually results from industrial inhalation of large quantities of lead oxide fumes or, in small children, from ingestion of a large oral dose of lead in the form of lead-based paint chips small objects, eg, toys coated or fabricated from lead or contaminated food or drink. The onset of severe symptoms usually requires several days or weeks of recurrent exposure and manifests as signs and symptoms of encephalopathy or colic. Evidence of hemolytic anemia (or anemia with basophilic stippling if exposure has been subacute), and elevated hepatic aminotransferases may be present. 

Interferon alfa preparations are available for treatment of both HBV and HCV virus infections. Interferon alfa-2b is the only preparation licensed for treatment of HBV infection and for acute hepatitis C. Interferon alfa-2b leads to loss of HBeAg, normalization of serum aminotransferases, and sustained histologic improvement in approximately one-third of patients with chronic hepatitis B, thus reducing the risk of progressive liver disease. 

Milk thistle has been used to treat acute and chronic viral hepatitis, alcoholic liver disease, and toxin-induced liver injury in human patients. Milk thistle has most often been studied in the treatment of alcoholic hepatitis and cirrhosis. In both of these disorders, outcomes have been mixed and reports include significant reductions in markers of liver dysfunction and in mortality, as well as no effect. In acute viral hepatitis, studies have generally involved small sample sizes and have shown mixed outcomes of improved liver function (eg, aminotransferase values, bilirubin, prothrombin time) or no effect. Studies in chronic viral hepatitis and toxin-induced injury have also been of small size but have reported mostly favorable results. Parenteral silybin is marketed and used in Europe as an antidote in Amanitaphalloides mushroom poisoning, based on favorable outcomes reported in case-control studies. 

The hepatotoxicity produced by acute carbon tetrachloride-induced liver injury was found to be inhibited by essential oil from fennel, as evidenced by decreased levels of serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and bilirubin (Ozbek et al., 2003). 

Liver. In humans, chronic Cd exposure does not typically result in hepatotoxicity. In laboratory animals, the liver accumulates the largest concentrations of Cd after acute or chronic exposures. In chronically exposed rats, liver injury occurs prior to renal dysfunction. Chronic Cd effects in the liver include increased plasma activities of alanine and aspartate aminotransferases, structural irregularities in hepatocytes, and decreased microsomal mixed function oxidase and CYP450 activities. Acute exposures in rats result in hepatic necrosis, particularly in parenchymal cells. Additionally, rough endoplasmic reticulum deteriorates, while smooth endoplasmic reticulum proliferates. Mitochondria are also degraded. As is the case with chronic exposure, microsomal mixed function oxidases and CYP450s are inhibited. 

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